WO2022145071A1 - Steel material - Google Patents
Steel material Download PDFInfo
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- WO2022145071A1 WO2022145071A1 PCT/JP2021/014788 JP2021014788W WO2022145071A1 WO 2022145071 A1 WO2022145071 A1 WO 2022145071A1 JP 2021014788 W JP2021014788 W JP 2021014788W WO 2022145071 A1 WO2022145071 A1 WO 2022145071A1
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- steel
- grain boundary
- steel material
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 142
- 239000010959 steel Substances 0.000 title claims abstract description 142
- 239000000463 material Substances 0.000 title claims abstract description 89
- 238000005204 segregation Methods 0.000 claims abstract description 79
- 239000013078 crystal Substances 0.000 claims abstract description 22
- 229910052735 hafnium Inorganic materials 0.000 claims abstract description 22
- 229910052726 zirconium Inorganic materials 0.000 claims abstract description 20
- 239000000203 mixture Substances 0.000 claims abstract description 18
- 239000000126 substance Substances 0.000 claims abstract description 18
- 229910052727 yttrium Inorganic materials 0.000 claims description 13
- 229910052684 Cerium Inorganic materials 0.000 claims description 11
- 229910052692 Dysprosium Inorganic materials 0.000 claims description 11
- 229910052693 Europium Inorganic materials 0.000 claims description 11
- 229910052765 Lutetium Inorganic materials 0.000 claims description 11
- 229910052772 Samarium Inorganic materials 0.000 claims description 11
- 229910052771 Terbium Inorganic materials 0.000 claims description 11
- 229910052706 scandium Inorganic materials 0.000 claims description 11
- 229910052691 Erbium Inorganic materials 0.000 claims description 10
- 229910052688 Gadolinium Inorganic materials 0.000 claims description 10
- 229910052689 Holmium Inorganic materials 0.000 claims description 10
- 229910052779 Neodymium Inorganic materials 0.000 claims description 10
- 229910052777 Praseodymium Inorganic materials 0.000 claims description 10
- 229910052775 Thulium Inorganic materials 0.000 claims description 10
- 229910052769 Ytterbium Inorganic materials 0.000 claims description 10
- 229910052746 lanthanum Inorganic materials 0.000 claims description 10
- 239000012535 impurity Substances 0.000 claims description 6
- 229910052787 antimony Inorganic materials 0.000 claims description 3
- 229910052745 lead Inorganic materials 0.000 claims description 3
- 229910052709 silver Inorganic materials 0.000 claims description 3
- 230000000694 effects Effects 0.000 description 45
- 230000007423 decrease Effects 0.000 description 23
- 238000004519 manufacturing process Methods 0.000 description 22
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 20
- 239000011651 chromium Substances 0.000 description 19
- 239000000523 sample Substances 0.000 description 18
- 239000010955 niobium Substances 0.000 description 17
- 230000007797 corrosion Effects 0.000 description 14
- 238000005260 corrosion Methods 0.000 description 14
- 239000011777 magnesium Substances 0.000 description 14
- 238000000034 method Methods 0.000 description 14
- 239000011669 selenium Substances 0.000 description 14
- 229910052717 sulfur Inorganic materials 0.000 description 14
- 239000011575 calcium Substances 0.000 description 13
- 239000010949 copper Substances 0.000 description 13
- 238000005098 hot rolling Methods 0.000 description 13
- 239000010936 titanium Substances 0.000 description 13
- 238000001816 cooling Methods 0.000 description 12
- 229910052757 nitrogen Inorganic materials 0.000 description 12
- 239000011572 manganese Substances 0.000 description 11
- 229910052760 oxygen Inorganic materials 0.000 description 11
- 238000007670 refining Methods 0.000 description 11
- 150000003568 thioethers Chemical class 0.000 description 11
- 229920006395 saturated elastomer Polymers 0.000 description 10
- 238000005496 tempering Methods 0.000 description 10
- 238000005259 measurement Methods 0.000 description 9
- 150000004767 nitrides Chemical class 0.000 description 9
- 239000006104 solid solution Substances 0.000 description 9
- 229910045601 alloy Inorganic materials 0.000 description 7
- 239000000956 alloy Substances 0.000 description 7
- 229910001566 austenite Inorganic materials 0.000 description 7
- 238000010438 heat treatment Methods 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 238000005266 casting Methods 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- 238000005096 rolling process Methods 0.000 description 4
- 230000000087 stabilizing effect Effects 0.000 description 4
- 238000005728 strengthening Methods 0.000 description 4
- 239000011593 sulfur Substances 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 229910052804 chromium Inorganic materials 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 238000001887 electron backscatter diffraction Methods 0.000 description 3
- 229910052749 magnesium Inorganic materials 0.000 description 3
- 229910000734 martensite Inorganic materials 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052698 phosphorus Inorganic materials 0.000 description 3
- 229910052711 selenium Inorganic materials 0.000 description 3
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 3
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 description 2
- 229910052785 arsenic Inorganic materials 0.000 description 2
- 229910052790 beryllium Inorganic materials 0.000 description 2
- 229910052797 bismuth Inorganic materials 0.000 description 2
- 229910052796 boron Inorganic materials 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000010884 ion-beam technique Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 229910052758 niobium Inorganic materials 0.000 description 2
- NJPPVKZQTLUDBO-UHFFFAOYSA-N novaluron Chemical compound C1=C(Cl)C(OC(F)(F)C(OC(F)(F)F)F)=CC=C1NC(=O)NC(=O)C1=C(F)C=CC=C1F NJPPVKZQTLUDBO-UHFFFAOYSA-N 0.000 description 2
- 239000011574 phosphorus Substances 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 229910052715 tantalum Inorganic materials 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- 238000007740 vapor deposition Methods 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910000760 Hardened steel Inorganic materials 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 229910052773 Promethium Inorganic materials 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 1
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- ATBAMAFKBVZNFJ-UHFFFAOYSA-N beryllium atom Chemical compound [Be] ATBAMAFKBVZNFJ-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- KBQHZAAAGSGFKK-UHFFFAOYSA-N dysprosium atom Chemical compound [Dy] KBQHZAAAGSGFKK-UHFFFAOYSA-N 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- OGPBJKLSAFTDLK-UHFFFAOYSA-N europium atom Chemical compound [Eu] OGPBJKLSAFTDLK-UHFFFAOYSA-N 0.000 description 1
- 230000005496 eutectics Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- VBJZVLUMGGDVMO-UHFFFAOYSA-N hafnium atom Chemical compound [Hf] VBJZVLUMGGDVMO-UHFFFAOYSA-N 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 230000001050 lubricating effect Effects 0.000 description 1
- OHSVLFRHMCKCQY-UHFFFAOYSA-N lutetium atom Chemical compound [Lu] OHSVLFRHMCKCQY-UHFFFAOYSA-N 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- VQMWBBYLQSCNPO-UHFFFAOYSA-N promethium atom Chemical compound [Pm] VQMWBBYLQSCNPO-UHFFFAOYSA-N 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 description 1
- SIXSYDAISGFNSX-UHFFFAOYSA-N scandium atom Chemical compound [Sc] SIXSYDAISGFNSX-UHFFFAOYSA-N 0.000 description 1
- 230000011218 segmentation Effects 0.000 description 1
- VSZWPYCFIRKVQL-UHFFFAOYSA-N selanylidenegallium;selenium Chemical compound [Se].[Se]=[Ga].[Se]=[Ga] VSZWPYCFIRKVQL-UHFFFAOYSA-N 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- 229910052714 tellurium Inorganic materials 0.000 description 1
- PORWMNRCUJJQNO-UHFFFAOYSA-N tellurium atom Chemical compound [Te] PORWMNRCUJJQNO-UHFFFAOYSA-N 0.000 description 1
- GZCRRIHWUXGPOV-UHFFFAOYSA-N terbium atom Chemical compound [Tb] GZCRRIHWUXGPOV-UHFFFAOYSA-N 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C19/00—Alloys based on nickel or cobalt
- C22C19/03—Alloys based on nickel or cobalt based on nickel
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C19/00—Alloys based on nickel or cobalt
- C22C19/03—Alloys based on nickel or cobalt based on nickel
- C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/10—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of nickel or cobalt or alloys based thereon
Definitions
- the present invention relates to steel materials.
- Elements segregated at the grain boundaries of the steel material may reduce the toughness, ductility, corrosion resistance, weldability, and other properties of the steel material.
- P phosphorus
- S sulfur
- C carbon
- Patent Document 1 describes a metal material in which crystal grains are made finer and embrittlement due to grain boundary segregation is suppressed. Patent Document 1 describes that grain boundary segregation is suppressed by miniaturizing the crystal grain size, and a metal material having an excellent balance between strength and ductility / toughness can be obtained.
- Patent Document 2 describes that in the case of ferritic stainless steel containing Nb, high-temperature cracking occurs due to welding due to the influence of Nb and P segregated at the grain boundaries.
- a liquid phase is generated at the grain boundaries at the time of welding due to eutectic melting of the low melting point phosphoric compound generated at the grain boundaries and the matrix, and liquefaction cracking occurs due to the applied stress.
- REM promotes grain boundary segregation of P and the like, and B tends to suppress it.
- Patent Document 3 describes a high-strength hot-rolled steel sheet in which an appropriate amount of C is segregated at the large-angle grain boundaries of ferrite to reduce damage to the punched end face.
- Patent Document 3 describes that P has an effect of embrittlement of grain boundaries, and if the segregation amount of P increases, the segregation amount of C may decrease.
- An object of the present invention is to provide a steel material in which the grain boundary segregation of P in steel is reduced by a novel configuration.
- the present inventors have investigated a new element capable of reducing the grain boundary segregation of P in steel.
- the present inventors secure the amount of the specific element solidly dissolved in the steel to a certain amount or more, and reduce the grain boundary segregation of P in the steel by segregating the specific element at the grain boundaries. We found that it was possible to complete the present invention.
- the steel materials that have achieved the above objectives are as follows. (1) By mass%, C: 0.001 to 1.000%, Si: 0.01-3.00%, Mn: 0.10 to 4.50%, P: 0.300% or less, S: 0.0300% or less, Al: 0.001-5.000%, N: 0.2000% or less, O: 0.0100% or less, At least one Z element selected from the group consisting of Zr: 0 to 0.8000% and Hf: 0 to 0.8000%.
- Nb 0-3.000%, Ti: 0 to 0.500%, Ta: 0 to 0.500%, V: 0 to 1.00%, Cu: 0 to 3.00%, Ni: 0-60.00%, Cr: 0 to 30.00%, Mo: 0 to 5.00%, W: 0 to 2.00%, B: 0-0.0200%, Co: 0 to 3.00%, Be: 0 to 0.050%, Ag: 0 to 0.500%, Ca: 0-0.0500%, Mg: 0-0.0500%, At least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc: 0 to 0.5000% in total.
- Sn 0 to 0.300%
- Sb 0 to 0.300%
- Te 0 to 0.100%
- Se 0 to 0.100%
- Bi 0 to 0.500%
- Pb 0 to 0.500%
- Fe and impurities It has a chemical composition that satisfies the following formula 1 and has a chemical composition.
- Nb 0.003 to 3.000%, Ti: 0.005 to 0.500%, Ta: 0.001 to 0.500%, V: 0.001 to 1.00%, Cu: 0.001 to 3.00%, Ni: 0.001 to 60.00%, Cr: 0.001 to 30.00%, Mo: 0.001 to 5.00%, W: 0.001 to 2.00%, B: 0.0001-0.0200%, Co: 0.001 to 3.00%, Be: 0.0003 to 0.050%, Ag: 0.001 to 0.500%, Ca: 0.0001-0.0500%, Mg: 0.0001-0.0500%, At least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc: 0.0001 to 0.5000% in total.
- the steel material according to the embodiment of the present invention is based on mass%.
- Nb 0-3.000%, Ti: 0 to 0.500%, Ta: 0 to 0.500%, V: 0 to 1.00%, Cu: 0 to 3.00%, Ni: 0-60.00%, Cr: 0 to 30.00%, Mo: 0 to 5.00%, W: 0 to 2.00%, B: 0-0.0200%, Co: 0 to 3.00%, Be: 0 to 0.050%, Ag: 0 to 0.500%, Ca: 0-0.0500%, Mg: 0-0.0500%, At least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc: 0 to 0.5000% in total.
- tempering treatment is performed at a predetermined temperature after quenching in order to secure low temperature toughness.
- P in the steel may segregate at the old austenite grain boundaries, causing so-called tempering embrittlement, and as a result, the toughness of the steel material may be lowered.
- the present inventors have investigated an element that can reduce the grain boundary segregation of P in steel.
- the present inventors have identified the amount of specific elements that are solid-dissolved in the steel, that is, the elements of Zr and Hf (hereinafter, also referred to as "Z element"), and the inclusions formed by these elements in the steel. More specifically, a certain amount or more is secured while considering the relationship between these elements with oxides, nitrides and sulfides (that is, the effective amount of the Z element corresponding to the left side of the formula 1 is 0.0003. % Or more), and further, it was found that the grain boundary segregation of P can be reduced by segregating the Z element at the grain boundary.
- the above-mentioned element Z has the property of easily forming inclusions composed of oxides, nitrides and sulfides in combination with O (oxygen), N (nitrogen) and S (sulfur) existing in the steel. Have.
- the amount of solid solution of the Z element that can be segregated at the grain boundaries is reduced, and the grain boundary segregation of P cannot be sufficiently reduced. ..
- the solid solution amount of the Z element in consideration of such inclusions is calculated as the effective amount of the Z element by the above formula 1 which will be described in detail later, and the effective amount is set to a certain amount or more, that is, 0.
- the Z element can be segregated at the grain boundary in a sufficient amount, and more specifically, the Z element is segregated at the grain boundary having a crystal orientation difference of 23 to 45 °.
- Segregation can be performed in an amount such that the total sum is 0.2 atoms / nm 2 or more, whereby the grain boundary segregation of P can be remarkably suppressed. Therefore, according to the present invention, it is possible to obtain a steel material in which the grain boundary segregation of P in the steel is sufficiently reduced without excessively reducing the P content, which is related to the grain boundary segregation of P. It is possible to remarkably improve the characteristics of the steel material, for example, the characteristics such as toughness, ductility, corrosion resistance, and weldability.
- the grain boundary crystal orientation difference of 23 to 45 ° does not necessarily limit the grain boundary where the Z element segregates, and the Z element segregates to the grain boundary having a crystal orientation difference other than the crystal orientation difference of 23 to 45 °.
- the grain boundaries having a crystal orientation difference of 23 to 45 ° correspond to the former austenite grain boundaries in the case of a steel material having a martensite structure. Therefore, by promoting the segregation of the Z element at the grain boundaries having such a crystal orientation difference, P segregates into the old austenite grain boundaries, for example, during the tempering treatment of a high-strength steel material having a martensite structure. Can be suppressed.
- the Z element in the present invention easily combines with O, N and S to form inclusions as described above, and therefore it is generally difficult to secure a predetermined solid solution amount in steel. Under these circumstances, the effect of reducing the grain boundary segregation of P by the Z element has not been known so far. However, recent advances in refining technology have made it possible to reduce the content of elements such as O, N, and S, which are generally present in steel as impurities, to extremely low levels. It was possible to realize a solid solution within a predetermined range of the Z element. Therefore, the effect of reducing the grain boundary segregation of P on the Z element has been clarified for the first time by the present inventors, and is extremely surprising and surprising.
- Carbon (C) is an element necessary for stabilizing hardness and / or ensuring strength. In order to sufficiently obtain these effects, the C content is 0.001% or more. The C content may be 0.005% or more, 0.010% or more, or 0.020% or more. On the other hand, if C is excessively contained, toughness, bendability and / or weldability may decrease. Therefore, the C content is 1.000% or less. The C content may be 0.800% or less, 0.600% or less, or 0.500% or less.
- Si is a deoxidizing element and is an element that also contributes to the improvement of strength. In order to sufficiently obtain these effects, the Si content is 0.01% or more. The Si content may be 0.05% or more, 0.10% or more, or 0.30% or more. On the other hand, if Si is excessively contained, the toughness may be lowered or surface quality defects called scale defects may occur. Therefore, the Si content is 3.00% or less. The Si content may be 2.00% or less, 1.00% or less, or 0.60% or less.
- Manganese (Mn) is an element effective for improving hardenability and / or strength, and is also an effective austenite stabilizing element. In order to sufficiently obtain these effects, the Mn content is 0.10% or more. The Mn content may be 0.50% or more, 0.70% or more, or 1.00% or more. On the other hand, if Mn is excessively contained, MnS harmful to toughness may be generated or the oxidation resistance may be lowered. Therefore, the Mn content is 4.50% or less. The Mn content may be 4.00% or less, 3.50% or less, or 3.00% or less.
- Phosphorus (P) is an element mixed in the manufacturing process. From the viewpoint of reducing the grain boundary segregation of P in the steel, the smaller the P, the more preferable, and the P content may be 0%. However, in order to reduce the P content to less than 0.0001%, it takes time for refining, which leads to a decrease in productivity. Therefore, the P content may be 0.0001% or more, 0.0005% or more, 0.001% or more, 0.003% or more, or 0.005% or more. The P content may be 0.007% or more from the viewpoint of manufacturing cost.
- the P content is 0.300% or less.
- the P content may be 0.100% or less, 0.030% or less, or 0.010% or less.
- S 0.0300% or less
- Sulfur (S) is an element mixed in the manufacturing process, and is preferable from the viewpoint of reducing inclusions formed with the Z element according to the embodiment of the present invention, so that the S content is 0%. There may be. However, in order to reduce the S content to less than 0.0001%, it takes time for refining, which leads to a decrease in productivity. Therefore, the S content may be 0.0001% or more, 0.0005% or more, or 0.0010% or more. On the other hand, if S is excessively contained, the effective amount of the Z element may decrease and the toughness may decrease. Therefore, the S content is 0.0300% or less.
- the S content is preferably 0.0100% or less, more preferably 0.0050% or less, and most preferably 0.0030% or less.
- Aluminum (Al) is a deoxidizing element and is also an effective element for improving corrosion resistance and / or heat resistance.
- the Al content is 0.001% or more.
- the Al content may be 0.010% or more, 0.100% or more, or 0.200% or more.
- the Al content may be 1.000% or more, 2.000% or more, or 3.000% or more.
- the Al content is 5.000% or less.
- the Al content may be 4.500% or less, 4000% or less, or 3.500% or less.
- the Al content may be 1.500% or less, 1.000% or less, or 0.300% or less.
- N Nitrogen (N) is an element mixed in the manufacturing process, and is preferable from the viewpoint of reducing inclusions formed with the Z element according to the embodiment of the present invention, so that the N content is 0%. There may be. However, in order to reduce the N content to less than 0.0001%, it takes time for refining, which leads to a decrease in productivity. Therefore, the N content may be 0.0001% or more, 0.0005% or more, or 0.0010% or more. On the other hand, N is also an element effective for stabilizing austenite, and may be intentionally contained if necessary. In this case, the N content is preferably 0.0100% or more, and may be 0.0200% or more and 0.0500% or more. However, if N is excessively contained, the effective amount of the Z element may decrease and the toughness may decrease. Therefore, the N content is 0.2000% or less. The N content may be 0.1500% or less, 0.1000% or less, or 0.0800% or less.
- Oxygen (O) is an element mixed in the manufacturing process, and is preferable from the viewpoint of reducing inclusions formed with the Z element according to the embodiment of the present invention, so that the O content is 0%. There may be. However, in order to reduce the O content to less than 0.0001%, it takes time for refining, which leads to a decrease in productivity. Therefore, the O content may be 0.0001% or more, 0.0005% or more, or 0.0010% or more. On the other hand, if O is excessively contained, coarse inclusions may be formed, the effective amount of the Z element may be lowered, and the formability and / or toughness of the steel material may be lowered. Therefore, the O content is 0.0100% or less. The O content may be 0.0080% or less, 0.0060% or less, or 0.0040% or less.
- the Z element according to the embodiment of the present invention is Zr: 0 to 0.8000% and Hf: 0 to 0.8000%, and zirconium (Zr) and hafnium (Hf) are present in the steel in a solid solution state.
- Zr zirconium
- Hf hafnium
- any one element may be used alone, or both may be used. Further, the Z element may be present in an amount satisfying Equation 1, which will be described in detail later, and the lower limit thereof is not particularly limited. However, for example, the content of each Z element or the total content may be 0.0010% or more, preferably 0.0050% or more, more preferably 0.0150% or more, and even more. It is preferably 0.0300% or more, and most preferably 0.0500% or more. On the other hand, even if the Z element is excessively contained, the effect is saturated, and therefore, if the Z element is contained in the steel material more than necessary, the manufacturing cost may increase.
- the content of each Z element is 0.8000% or less, for example, 0.7000% or less, 0.6000% or less, 0.5000% or less, 0.4000% or less, or 0.3000% or less. May be good.
- the total content of the Z element is 1.6000% or less, for example, 1.2000% or less, 1.000% or less, 0.8000% or less, 0.6000% or less, or 0.5000% or less. You may.
- the steel material may contain one or more of the following optional elements, if necessary.
- the steel material has Nb: 0 to 3.000%, Ti: 0 to 0.500%, Ta: 0 to 0.500%, V: 0 to 1.00%, Cu: 0 to 3.00%, Ni: 0 to 60.00%, Cr: 0 to 30.00%, Mo: 0 to 5.00%, W: 0 to 2.00%, B: 0 to 0.0200%, Co: 0 to 3 It may contain one or more of 0.00%, Be: 0 to 0.050%, and Ag: 0 to 0.500%.
- the steel materials include Ca: 0 to 0.0500%, Mg: 0 to 0.0500%, and La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er. At least one of Tm, Yb, Lu, and Sc: one or more of 0 to 0.5000% in total may be contained. Further, the steel material may contain one or two of Sn: 0 to 0.300% and Sb: 0 to 0.300%. The steel materials are Te: 0 to 0.100%, Se: 0 to 0.100%, As: 0 to 0.050%, Bi: 0 to 0.500%, and Pb: 0 to 0.500%. One or more of them may be contained. Hereinafter, these optional elements will be described in detail.
- Niobium (Nb) is an element that contributes to strengthening precipitation and suppressing recrystallization.
- the Nb content may be 0%, but in order to obtain these effects, the Nb content is preferably 0.003% or more.
- the Nb content may be 0.005% or more or 0.010% or more.
- the Nb content may be 1.000% or more or 1.500% or more from the viewpoint of sufficiently strengthening precipitation.
- the Nb content is 3.000% or less.
- the Nb content may be 2.800% or less, 2.500% or less, or 2.000% or less.
- the Nb content is preferably 0.100% or less, 0.080% or less, 0.050% or less, or 0.030. It may be less than or equal to%.
- Titanium (Ti) is an element that contributes to improving the strength of steel materials by strengthening precipitation.
- the Ti content may be 0%, but in order to obtain such an effect, the Ti content is preferably 0.005% or more.
- the Ti content may be 0.010% or more, 0.050% or more, or 0.080% or more.
- the Ti content is 0.500% or less.
- the Ti content may be 0.300% or less, 0.200% or less, or 0.100% or less.
- Tantalum (Ta) is an element effective in controlling the morphology of carbides and increasing their strength.
- the Ta content may be 0%, but in order to obtain these effects, the Ta content is preferably 0.001% or more.
- the Ta content may be 0.005% or more, 0.010% or more, or 0.050% or more.
- the Ta content is 0.500% or less.
- the Ta content may be 0.300% or less, 0.100% or less, or 0.080% or less.
- Vanadium (V) is an element that contributes to improving the strength of steel materials by strengthening precipitation.
- the V content may be 0%, but in order to obtain such an effect, the V content is preferably 0.001% or more.
- the V content may be 0.01% or more, 0.02% or more, 0.05% or more, or 0.10% or more.
- the V content is 1.00% or less.
- the V content may be 0.80% or less, 0.60% or less, or 0.50% or less.
- Copper (Cu) is an element that contributes to the improvement of strength and / or corrosion resistance.
- the Cu content may be 0%, but in order to obtain these effects, the Cu content is preferably 0.001% or more.
- the Cu content may be 0.01% or more, 0.10% or more, 0.15% or more, 0.20% or more, or 0.30% or more.
- the Cu content is 3.00% or less.
- the Cu content may be 2.00% or less, 1.50% or less, 1.00% or less, or 0.50% or less.
- Nickel (Ni) is an element that contributes to the improvement of strength and / or heat resistance, and is also an effective austenite stabilizing element.
- the Ni content may be 0%, but in order to obtain these effects, the Ni content is preferably 0.001% or more.
- the Ni content may be 0.01% or more, 0.10% or more, 0.50% or more, 0.70% or more, 1.00% or more, or 3.00% or more.
- the Ni content may be 30.00% or more, 35.00% or more, or 40.00% or more.
- the deformation resistance during hot working increases in addition to the increase in alloy cost, which may increase the equipment load.
- the Ni content is 60.00% or less.
- the Ni content may be 55.00% or less or 50.00% or less.
- the Ni content is 15.00% or less, 10.00% or less, 6.00% or less, or 4.00% or less. You may.
- Chromium (Cr) is an element that contributes to the improvement of strength and / or corrosion resistance.
- the Cr content may be 0%, but in order to obtain these effects, the Cr content is preferably 0.001% or more.
- the Cr content may be 0.01% or more, 0.05% or more, 0.10% or more, or 0.50% or more.
- the Cr content may be 10.00% or more, 12.00% or more, or 15.00% or more.
- the Cr content is 30.00% or less.
- the Cr content may be 28.00% or less, 25.00% or less, or 20.00% or less.
- the Cr content may be 10.00% or less, 9.00% or less, or 7.50% or less.
- Molybdenum is an element that enhances the hardenability of steel and contributes to the improvement of strength, and is also an element that contributes to the improvement of corrosion resistance.
- the Mo content may be 0%, but in order to obtain these effects, the Mo content is preferably 0.001% or more.
- the Mo content may be 0.01% or more, 0.02% or more, 0.50% or more, or 1.00% or more.
- Mo content is 5.00% or less.
- the Mo content may be 4.50% or less, 4.00% or less, 3.00 or less, or 1.50% or less.
- Tungsten is an element that enhances the hardenability of steel and contributes to the improvement of strength.
- the W content may be 0%, but in order to obtain such an effect, the W content is preferably 0.001% or more.
- the W content may be 0.01% or more, 0.02% or more, 0.05% or more, 0.10% or more, or 0.50% or more.
- the W content is 2.00% or less.
- the W content may be 1.80% or less, 1.50% or less, or 1.00% or less.
- B is an element that contributes to the improvement of strength.
- the B content may be 0%, but in order to obtain such an effect, the B content is preferably 0.0001% or more.
- the B content may be 0.0003% or more, 0.0005% or more, or 0.0007% or more.
- the B content is 0.0200% or less.
- the B content may be 0.0100% or less, 0.0050% or less, 0.0030% or less, or 0.0020% or less.
- Co is an element that contributes to the improvement of hardenability and / or heat resistance.
- the Co content may be 0%, but in order to obtain these effects, the Co content is preferably 0.001% or more.
- the Co content may be 0.01% or more, 0.02% or more, 0.05% or more, 0.10% or more, or 0.50% or more.
- the Co content is 3.00% or less.
- the Co content may be 2.50% or less, 2.00% or less, 1.50% or less, or 0.80% or less.
- Beryllium (Be) is an element effective for increasing the strength of the base metal and refining the structure.
- the Be content may be 0%, but in order to obtain such an effect, the Be content is preferably 0.0003% or more.
- the Be content may be 0.0005% or more, 0.001% or more, or 0.010% or more.
- the Be content is 0.050% or less.
- the Be content may be 0.040% or less, 0.030% or less, or 0.020% or less.
- Silver (Ag) is an element effective for increasing the strength of the base material and refining the structure.
- the Ag content may be 0%, but in order to obtain such an effect, the Ag content is preferably 0.001% or more.
- the Ag content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.050% or more.
- the Ag content is 0.500% or less.
- the Ag content may be 0.400% or less, 0.300% or less, or 0.200% or less.
- Ca 0-0.0500%
- Ca is an element that can control the morphology of sulfides.
- the Ca content may be 0%, but in order to obtain such an effect, the Ca content is preferably 0.0001% or more.
- the Ca content is 0.0500% or less.
- Magnesium (Mg) is an element that can control the morphology of sulfides.
- the Mg content may be 0%, but in order to obtain such an effect, the Mg content is preferably 0.0001% or more.
- the Mg content may be greater than 0.0015%, greater than 0.0016%, greater than or equal to 0.0018% or greater than or equal to 0.0020%.
- the Mg content is 0.0500% or less.
- the Mg content may be 0.0400% or less, 0.0300% or less, or 0.0200% or less.
- the total content of at least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc is 0%. However, in order to obtain such an effect, it is preferably 0.0001% or more.
- the total content of at least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc is 0.0002% or more. It may be 0.0003% or more or 0.0004% or more.
- the total content of at least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc is 0.5000%. It may be less than or equal to 0.4000%, 0.3000% or less, or 0.2000% or less.
- Tin (Sn) is an element effective for improving corrosion resistance.
- the Sn content may be 0%, but in order to obtain such an effect, the Sn content is preferably 0.001% or more.
- the Sn content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.050% or more.
- the Sn content is 0.300% or less.
- the Sn content may be 0.250% or less, 0.200% or less, or 0.150% or less.
- Antimony (Sb) is an element effective for improving corrosion resistance like Sn, and the effect can be increased by including it in combination with Sn.
- the Sb content may be 0%, but in order to obtain the effect of improving the corrosion resistance, the Sb content is preferably 0.001% or more.
- the Sb content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.050% or more.
- excessive content of Sb may lead to a decrease in toughness, particularly low temperature toughness. Therefore, the Sb content is 0.300% or less.
- the Sb content may be 0.250% or less, 0.200% or less, or 0.150% or less.
- Tellurium is an element effective for improving the machinability of steel because it forms a low melting point compound with Mn, S and the like to enhance the lubricating effect.
- the Te content may be 0%, but in order to obtain such an effect, the Te content is preferably 0.001% or more.
- the Te content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.040% or more.
- the Te content is 0.100% or less.
- the Te content may be 0.090% or less, 0.080% or less, or 0.070% or less.
- Selenium (Se) is an effective element for improving the machinability of steel because the selenium produced in the steel changes the shear-plastic deformation of the work material and the chips are easily crushed. ..
- the Se content may be 0%, but in order to obtain such an effect, the Se content is preferably 0.001% or more.
- the Se content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.040% or more.
- the Se content is 0.100% or less.
- the Se content may be 0.090% or less, 0.080% or less, or 0.070% or less.
- Arsenic (As) is an element effective in improving the machinability of steel.
- the As content may be 0%, but in order to obtain such an effect, the As content is preferably 0.001% or more.
- the As content may be 0.005% or more or 0.010% or more.
- the As content is 0.050% or less.
- the As content may be 0.040% or less, 0.030% or less, or 0.020% or less.
- Bismuth (Bi) is an element effective in improving the machinability of steel.
- the Bi content may be 0%, but in order to obtain such an effect, the Bi content is preferably 0.001% or more.
- the Bi content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.050% or more.
- the Bi content is 0.500% or less.
- the Bi content may be 0.400% or less, 0.300% or less, or 0.200% or less.
- Pb 0 to 0.500%
- Lead (Pb) is an element effective for improving the machinability of steel because it melts when the temperature rises due to cutting and promotes the growth of cracks.
- the Pb content may be 0%, but in order to obtain such an effect, the Pb content is preferably 0.001% or more.
- the Pb content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.050% or more.
- the Pb content is 0.500% or less.
- the Pb content may be 0.400% or less, 0.300% or less, or 0.200% or less.
- the balance other than the above elements consists of Fe and impurities.
- Impurities are components that are mixed in by various factors in the manufacturing process, including raw materials such as ore and scrap, when steel materials are industrially manufactured.
- the effective amount of the Z element consisting of Zr and Hf is determined by the left side of the following formula 1, and the value thereof satisfies the following formula 1. 0.61 [Zr] +0.31 [Hf] -1.75 [O] -3.99 [N] -1.74 [S] ⁇ 0.0003 ⁇ ⁇ ⁇ Equation 1
- [Zr], [Hf], [O], [N], and [S] are the content [mass%] of each element, and are 0 when the element is not contained.
- the effective amount of the Z element By making the effective amount of the Z element satisfy the above formula 1, the amount of these elements existing in the solid solution state in the steel can be increased, so that the Z element can be sufficiently applied to the grain boundary. It is possible to segregate in a large amount, and as a result, it is possible to reduce the grain boundary segregation of P. More specifically, these Z elements (hereinafter, also simply referred to as “Z”) are combined with O (oxygen), N (nitrogen) and S (sulfur) present in steel to form an oxide (ZO 2 ). , Tends to form inclusions consisting of nitrides (ZN) and sulfides (ZS). Once the inclusions are formed, at least the Z element in these inclusions cannot segregate at the grain boundaries.
- ZN nitrides
- ZS sulfides
- the Z element existing in the steel in a solid solution state without forming inclusions is formed. It is necessary to increase the amount (that is, the solid solution amount of the Z element in the steel).
- the solid solution amount of the Z element in the steel is obtained by subtracting the maximum amount that can be consumed to form inclusions (oxides, nitrides and sulfides) from the amount of the Z element contained in the steel. It is possible to make an approximation. Therefore, in the embodiment of the present invention, the amount of Z element effective for reducing the grain boundary segregation of P in the steel estimated in this way (that is, "effective amount of Z element") is concrete. Is defined by the following formula A.
- Effective amount of Z element [atomic%] ⁇ (M [Fe] / M [Z] ) x [Z]-(M [Fe] / M [O] ) x [O] x 1 / 2- (M [ ] Fe] / M [N] ) x [N]-(M [Fe] / M [S] ) x [S] ... Equation A
- Z represents each Z element of Zr and Hf
- M [Z] is the atomic weight of the Z element
- M [Fe] is the atomic weight of Fe
- M [O] is the atomic weight of O
- M [N] is N.
- M [S] represents the atomic weight of S
- [Z], [O], [N], and [S] are the corresponding element content [mass%], respectively, when no element is contained. Is 0.
- the steel material according to the embodiment of the present invention contains various alloying elements, the steel material as a whole is almost composed of Fe or is an optional element.
- the steel material when a certain Ni and / or Cr is contained in a relatively large amount (the maximum contents are 60.00% and 30.00%, respectively), it is clear that it is almost composed of Ni and / or Cr in addition to Fe. Is.
- the atomic weights of Ni and Cr are equivalent to the atomic weights of Fe. Therefore, even when the steel material contains a relatively large amount of Ni and / or Cr, the atomic% of each Z element of Zr and Hf is approximately Fe in the content [mass%] of each Z element.
- the effective amount of the Z element for reducing the grain boundary segregation of P can be defined by the following formula A.
- Effective amount of Z element [atomic%] ⁇ (M [Fe] / M [Z] ) x [Z]-(M [Fe] / M [O] ) x [O] x 1 / 2- (M [ ] Fe] / M [N] ) x [N]-(M [Fe] / M [S] ) x [S] ... Equation A
- [Zr], [Hf], [O], [N], and [S] are the content [mass%] of each element, and are 0 when the element is not contained.
- the effective amount of the Z element determined by the above formula B is 0.0003% or more, that is, at least satisfy the following formula 1. .. 0.61 [Zr] +0.31 [Hf] -1.75 [O] -3.99 [N] -1.74 [S] ⁇ 0.0003 ⁇ ⁇ ⁇ Equation 1
- the effective amount of the Z element may be, for example, 0.0005% or more or 0.0007% or more, preferably 0.0010% or more, more preferably 0.0015% or more, still more preferably 0.0030%. The above is most preferably 0.0050% or more or 0.0100% or more.
- the effective amount of the Z element is 2.000% or less, for example, even if it is 1.8000% or less, 1.5000% or less, 1.2000% or less, 1.000% or less, or 0.8000% or less. good.
- the total amount of segregation of Zr and Hf at grain boundaries with a crystal orientation difference of 23 to 45 ° is 0.2 atoms / nm 2 or more]
- Z elements that is, Zr and Hf
- Zr and Hf are segregated at grain boundaries having a crystal orientation difference of 23 to 45 ° at an amount such that the total segregation amount is 0.2 atoms / nm 2 or more. If this is the case, the effect of the Z element can be sufficiently exerted, so that the grain boundary segregation of P can be reliably reduced.
- the total segregation amount of the Z element is preferably 0.3 atoms / nm 2 or more, more preferably 0.4 atoms / nm 2 or more, still more preferably 0.6 atoms / nm 2 or more, and most preferably 0.7 atoms. / Nm 2 or more or 1.0 atoms / nm 2 or more.
- the upper limit of the total sum of segregation amounts is not particularly limited, but even if the segregation amount is excessively increased, the effect is saturated and the manufacturing cost increases (the alloy cost increases due to the increase in the content of Z element and / or O). , Increase in refining cost for N and S), which is not always preferable.
- the total segregation amount is 5.0 atoms / nm 2 or less, for example, 4.5 atoms / nm 2 or less, 4.0 atoms / nm 2 or less, 3.5 atoms / nm 2 or less, 3.2 atoms / nm 2 or less. Alternatively, it may be 3.0 atoms / nm 2 or less.
- a minute block is cut out from this grain boundary by a lift-out method of FIB (focused ion beam processing).
- the block is attached to the needle pedestal by a Pt vapor deposition method or the like, and FIB processing is performed so that the grain boundaries in the block are located at the needle tip.
- This needle sample is measured by the three-dimensional atom probe method.
- the three-dimensional atom probe measurement may be either a normal electrode type or a local electrode type, and the measurement mode may be either a voltage mode or a laser mode. In the voltage mode, the sample temperature is 50 to 70 K, the applied voltage is 3 to 15 kV, and the pulse ratio indicating the ratio of the pulse voltage to the DC voltage is 15 to 25%.
- the sample temperature is 30 to 60 K
- the laser pulse energy is a value corresponding to a pulse ratio of 10 to 30%.
- a 3D element map including the grain boundary can be obtained by using the dedicated 3D construction software.
- the grain boundary positions can be recognized from the positions where the elements are concentrated in a planar manner and the atomic planes are discontinuous.
- a selection box larger than 10 nm ⁇ 10 nm ⁇ 10 nm is set so as to cross perpendicular to the grain interface, for example, a selection box of 20 nm ⁇ 20 nm parallel to the grain boundary and 30 nm perpendicular to the grain boundary is set and perpendicular to the grain interface.
- a ladder chart is drawn for each segregating element in the direction (see, for example, FIG. 2 of JP-A-2008-261029).
- the grain boundary area for example, 20 nm ⁇ 20 nm
- the ion detection rate of the three-dimensional atom probe It is possible to obtain the Interfacial Excess value indicating the amount of grain boundary segregation.
- the arithmetic average of the total value of the interfacial excess values indicating the amount of grain boundary segregation of the Z element (Zr and Hf) obtained by performing the same measurement at 5 points in the steel material is "a crystal orientation difference of 23 to 45 °.” It is determined as "the total amount of segregation of Z elements (Zr and Hf) at the grain boundary".
- the steel material according to the embodiment of the present invention has a grain boundary with a crystal orientation difference of 23 to 45 ° in the arithmetic mean when five points in the steel material are measured by the three-dimensional atom probe method, and Zr and Hf.
- the total segregation amount of Zr and Hf in the steel material containing grain boundaries with a total segregation amount of 0.2 atoms / nm 2 or more, or the grain boundaries with a crystal orientation difference of 23 to 45 ° is 0.2 atoms / nm 2 or more. It can also be said that it is a steel material.
- the steel material according to the embodiment of the present invention may be any steel material in which the Z element is segregated at the grain boundaries, and is not particularly limited.
- the steel material according to the embodiment of the present invention includes, for example, thick steel plates, thin steel plates, steel bars, wire rods, shaped steels, steel pipes, and the like.
- the steel material according to the embodiment of the present invention can be manufactured by any suitable method known to those skilled in the art, depending on the form of the final product and the like.
- the manufacturing method includes a step generally applied when manufacturing the thick steel plate, for example, a step of casting a slab having the chemical composition described above, and casting. It includes a step of hot rolling the slab and a step of cooling the obtained rolled material, and may further include a quenching step, a tempering step and the like, if necessary.
- the steel material manufacturing process according to the embodiment of the present invention may be a thermal processing control process (TMCP) that combines controlled rolling and accelerated cooling.
- TMCP thermal processing control process
- the manufacturing method includes a step generally applied when manufacturing the thin steel plate, for example, a step of casting a slab having the chemical composition described above, and casting. It may further include a step of hot rolling the slab, a step of cooling and winding the obtained rolled material, a cold rolling step, a baking step and the like, if necessary.
- a step generally applied when manufacturing steel bars and other steel materials is included, and for example, a steelmaking process for forming molten steel having the chemical composition described above is formed. It includes a step of casting slabs, billets, blooms, etc.
- the segregation of the Z element into the grain boundaries can be controlled by the heat history in the hot rolling process or the heat treatment after the hot rolling process.
- the hot rolling may be performed in consideration of the temperature and time range in which each Z element segregates, and then the cooling may be performed in the cooling step.
- a thermal history includes setting the holding time in the temperature range of 850 to 1100 ° C. for 5 seconds or more after rough rolling and / or finish rolling.
- retention includes a case where the temperature gradually decreases due to cooling, air cooling, or the like within the above temperature range.
- the upper limit of the holding time is not particularly limited, but may be, for example, 1800 seconds or less.
- the Z element can be segregated at the grain boundary by performing a heat treatment of heating, holding and cooling to a temperature at which each Z element segregates.
- the holding time in the temperature range of 850 to 1100 ° C. may be 5 seconds or longer, preferably 10 seconds or longer, and cooling may be performed.
- the upper limit of the holding time is not particularly limited, but may be, for example, 1800 seconds or less or 600 seconds or less.
- the heating temperature of the heat treatment is high, for example, if it is heated to 1200 ° C. or higher and cooled without holding it in the temperature range of 850 to 1100 ° C., the distribution of each Z element becomes uniform and the grain boundary segregation may decrease. be.
- the Z element can be sufficiently segregated to the grain boundaries by the thermal history of the hot rolling process or the heat treatment after the hot rolling process, P is segregated to the grain boundaries even by the subsequent tempering treatment or the like. It can be suppressed. As a result, it is possible to suppress the occurrence of tempering embrittlement and the like, and therefore it is possible to significantly improve the toughness and other properties of the steel material. Further, in the production of the steel material according to the embodiment of the present invention, it is important to secure an effective amount of Z element for reducing the grain boundary segregation of P, and for that purpose, Z element and inclusions in the steel are used. It is extremely important that the contents of O, N and S that can be formed are sufficiently reduced in the refining step.
- Examples 1 to 83 and Comparative Examples 84 to 90 First, slabs having various chemical compositions were cast, and then hot rolling was carried out at a rolling reduction of 50% or more and cooled. Next, the obtained rolled material was heated, held at a predetermined temperature in the range of 850 to 1100 ° C. for 20 to 50 seconds, and then rapidly cooled to obtain a steel material in which the Z element was segregated at the grain boundaries.
- Example 91 Hot rolling was carried out in the same manner as in Example 1, and after cooling, the rolled material was heated to 1200 ° C. and held for 50 seconds, and then rapidly cooled to obtain a steel material.
- the chemical compositions obtained by analyzing the samples collected from the steel materials obtained in Examples and Comparative Examples are as shown in Table 1 below.
- the grain boundary segregation amount of the Z element in each of the obtained steel materials was measured by the following method.
- the amount of segregation of the Z element at the grain boundaries having a crystal orientation difference of 23 to 45 ° was determined by using the three-dimensional atom probe method. More specifically, first, a grain boundary having a crystal orientation difference of 23 to 45 ° was selected from the grain boundaries in the sample collected from the 1 / 4t portion of the steel material by EBSD. Next, a minute block was cut out from this grain boundary by a lift-out method of FIB (focused ion beam processing). The block was attached to the needle pedestal by the Pt vapor deposition method, and FIB processing was performed so that the grain boundaries in the block were located at the needle tip.
- FIB focused ion beam processing
- This needle sample was measured by a three-dimensional atom probe method (normal electrode type, measurement mode: voltage mode, sample temperature: 50 to 70 K, applied voltage: 3 to 15 kV, and pulse ratio: 15 to 25%). From the data acquired by the 3D atom probe measurement, a 3D element map including the grain boundary is obtained using the dedicated 3D construction software, and 20 nm in the direction parallel to the grain boundary so as to cross perpendicular to the grain interface. A selection box of ⁇ 20 nm and 30 nm in the direction perpendicular to the grain boundary was set, and a ladder chart was drawn for each segregated element in the direction perpendicular to the grain interface.
- the grain boundary segregation amount of P after the tempering treatment was 0.4 atoms / nm 2 or less was evaluated as a steel material in which the grain boundary segregation of P in the steel was reduced.
- Table 1 in Comparative Examples 84 to 90, since the effective amount of the Z element composed of Zr and Hf was low, the Z element could not be segregated at the grain boundaries, and as a result, the grains of P in the steel material could not be segregated. The field segregation could not be reduced.
- the effective amount of the Z element was higher than 0.0003%, and therefore satisfied the formula 1, but the Z element could be sufficiently segregated at the grain boundaries in the manufacturing process.
- the effective amount of the Z element is 0.0003% or more, and the Z element is sufficiently segregated at the grain boundaries to allow P in the steel material. It was possible to reduce the grain boundary segregation.
- the steel material according to the embodiment of the present invention is a steel material after hot rolling in which the Z element is segregated at the grain boundary, for example, thick steel sheets used for bridges, construction, shipbuilding, pressure vessels, etc., automobiles, home appliances, etc. It also includes thin steel plates used in the above, as well as steel bars, wire rods, shaped steels, steel pipes, and the like.
- the grain boundary segregation of P in the steel is sufficiently reduced, so that the characteristics of the steel material related to the grain boundary segregation of P, for example, , Toughness, ductility, corrosion resistance, weldability and other properties can be significantly improved.
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Abstract
Provided is a steel material having a predetermined chemical composition satisfying 0.61[Zr]+0.31[Hf]-1.75[O]-3.99[N]-1.74[S]≥0.0003 (in the expression, [Zr], [Hf], [O], [N], and [S] are each the content [mass%] of an element), the steel material including grain boundaries which have a crystal orientation difference of 23-45° and in which the total segregation amount of Zr and Hf is at least 0.2 atoms/nm2.
Description
本発明は、鋼材に関する。
The present invention relates to steel materials.
鋼材の結晶粒界に偏析した元素、例えば、リン(P)、硫黄(S)、炭素(C)などは、鋼材の靭性、延性、耐食性及び溶接性などの特性を低下させる場合があることが知られている。一般に、鋼材のこれらの特性を向上させるためには、粒界偏析を低減することが重要であると考えられている。
Elements segregated at the grain boundaries of the steel material, such as phosphorus (P), sulfur (S), carbon (C), etc., may reduce the toughness, ductility, corrosion resistance, weldability, and other properties of the steel material. Are known. It is generally considered important to reduce grain boundary segregation in order to improve these properties of steel materials.
これに関連して、特許文献1では、結晶粒を微細化し、粒界偏析に起因する脆化を抑制した金属材料が記載されている。特許文献1では、結晶粒径の微細化により粒界偏析が抑制され、強度と延性・靭性のバランスに優れた金属材料が得られることが記載されている。
In relation to this, Patent Document 1 describes a metal material in which crystal grains are made finer and embrittlement due to grain boundary segregation is suppressed. Patent Document 1 describes that grain boundary segregation is suppressed by miniaturizing the crystal grain size, and a metal material having an excellent balance between strength and ductility / toughness can be obtained.
特許文献2では、Nbを含有するフェライト系ステンレス鋼の場合、粒界に偏析したNbとPの影響で、溶接による高温割れが発生することが記載されている。特許文献2では、結晶粒界に生成した低融点のリン化物と母相との共晶融解によって、溶接時に粒界に液相が生成し、負荷された応力により液化割れが発生すること、S、REMがP等の粒界偏析を助長し、Bがそれを抑制する傾向にあることが記載されている。
Patent Document 2 describes that in the case of ferritic stainless steel containing Nb, high-temperature cracking occurs due to welding due to the influence of Nb and P segregated at the grain boundaries. In Patent Document 2, a liquid phase is generated at the grain boundaries at the time of welding due to eutectic melting of the low melting point phosphoric compound generated at the grain boundaries and the matrix, and liquefaction cracking occurs due to the applied stress. , REM promotes grain boundary segregation of P and the like, and B tends to suppress it.
特許文献3では、フェライトの大角結晶粒界に適正な量のCを偏析させて、打ち抜き端面の損傷を減少させた高強度熱延鋼板が記載されている。特許文献3では、Pは粒界を脆化させる効果を持ち、Pの偏析量が増加すると、Cの偏析量を低下させる恐れがあることが記載されている。
Patent Document 3 describes a high-strength hot-rolled steel sheet in which an appropriate amount of C is segregated at the large-angle grain boundaries of ferrite to reduce damage to the punched end face. Patent Document 3 describes that P has an effect of embrittlement of grain boundaries, and if the segregation amount of P increases, the segregation amount of C may decrease.
本発明の目的とするところは、新規な構成により、鋼中のPの粒界偏析が低減された鋼材を提供することにある。
An object of the present invention is to provide a steel material in which the grain boundary segregation of P in steel is reduced by a novel configuration.
本発明者らは、上記目的を達成するために、鋼中のPの粒界偏析を低減させることのできる、新たな元素について検討を行った。その結果、本発明者らは、鋼中に固溶している特定元素の量を一定量以上確保するとともに、当該特定元素を粒界に偏析させることで鋼中のPの粒界偏析を低減させることができることを見出し、本発明を完成させた。
In order to achieve the above object, the present inventors have investigated a new element capable of reducing the grain boundary segregation of P in steel. As a result, the present inventors secure the amount of the specific element solidly dissolved in the steel to a certain amount or more, and reduce the grain boundary segregation of P in the steel by segregating the specific element at the grain boundaries. We found that it was possible to complete the present invention.
上記目的を達成し得た鋼材は、以下のとおりである。
(1)質量%で、
C:0.001~1.000%、
Si:0.01~3.00%、
Mn:0.10~4.50%、
P:0.300%以下、
S:0.0300%以下、
Al:0.001~5.000%、
N:0.2000%以下、
O:0.0100%以下、
Zr:0~0.8000%、及びHf:0~0.8000%からなる群より選択される少なくとも1種のZ元素、
Nb:0~3.000%、
Ti:0~0.500%、
Ta:0~0.500%、
V:0~1.00%、
Cu:0~3.00%、
Ni:0~60.00%、
Cr:0~30.00%、
Mo:0~5.00%、
W:0~2.00%、
B:0~0.0200%、
Co:0~3.00%、
Be:0~0.050%、
Ag:0~0.500%、
Ca:0~0.0500%、
Mg:0~0.0500%、
La、Ce、Nd、Y、Pm、Pr、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、及びScの少なくとも1種:合計で0~0.5000%、
Sn:0~0.300%、
Sb:0~0.300%、
Te:0~0.100%、
Se:0~0.100%、
As:0~0.050%、
Bi:0~0.500%、
Pb:0~0.500%、並びに
残部:Fe及び不純物からなり、
下記式1を満たす化学組成を有し、
結晶方位差が23~45°の粒界であって、Zr及びHfの偏析量の総和が0.2atoms/nm2以上である粒界を含む、鋼材。
0.61[Zr]+0.31[Hf]-1.75[O]-3.99[N]-1.74[S] ≧ 0.0003 ・・・式1
ここで、[Zr]、[Hf]、[O]、[N]、及び[S]は、各元素の含有量[質量%]であり、元素を含有しない場合は0である。
(2)前記化学組成が、質量%で、
Nb:0.003~3.000%、
Ti:0.005~0.500%、
Ta:0.001~0.500%、
V:0.001~1.00%、
Cu:0.001~3.00%、
Ni:0.001~60.00%、
Cr:0.001~30.00%、
Mo:0.001~5.00%、
W:0.001~2.00%、
B:0.0001~0.0200%、
Co:0.001~3.00%、
Be:0.0003~0.050%、
Ag:0.001~0.500%、
Ca:0.0001~0.0500%、
Mg:0.0001~0.0500%、
La、Ce、Nd、Y、Pm、Pr、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、及びScの少なくとも1種:合計で0.0001~0.5000%、
Sn:0.001~0.300%、
Sb:0.001~0.300%、
Te:0.001~0.100%、
Se:0.001~0.100%、
As:0.001~0.050%、
Bi:0.001~0.500%、並びに
Pb:0.001~0.500%
のうち1種又は2種以上を含む、上記(1)に記載の鋼材。 The steel materials that have achieved the above objectives are as follows.
(1) By mass%,
C: 0.001 to 1.000%,
Si: 0.01-3.00%,
Mn: 0.10 to 4.50%,
P: 0.300% or less,
S: 0.0300% or less,
Al: 0.001-5.000%,
N: 0.2000% or less,
O: 0.0100% or less,
At least one Z element selected from the group consisting of Zr: 0 to 0.8000% and Hf: 0 to 0.8000%.
Nb: 0-3.000%,
Ti: 0 to 0.500%,
Ta: 0 to 0.500%,
V: 0 to 1.00%,
Cu: 0 to 3.00%,
Ni: 0-60.00%,
Cr: 0 to 30.00%,
Mo: 0 to 5.00%,
W: 0 to 2.00%,
B: 0-0.0200%,
Co: 0 to 3.00%,
Be: 0 to 0.050%,
Ag: 0 to 0.500%,
Ca: 0-0.0500%,
Mg: 0-0.0500%,
At least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc: 0 to 0.5000% in total.
Sn: 0 to 0.300%,
Sb: 0 to 0.300%,
Te: 0 to 0.100%,
Se: 0 to 0.100%,
As: 0 to 0.050%,
Bi: 0 to 0.500%,
Pb: 0 to 0.500%, and the balance: Fe and impurities.
It has a chemical composition that satisfies the following formula 1 and has a chemical composition.
A steel material containing grain boundaries having a crystal orientation difference of 23 to 45 ° and a total segregation amount of Zr and Hf of 0.2 atoms / nm 2 or more.
0.61 [Zr] +0.31 [Hf] -1.75 [O] -3.99 [N] -1.74 [S] ≧ 0.0003 ・ ・ ・ Equation 1
Here, [Zr], [Hf], [O], [N], and [S] are the content [mass%] of each element, and are 0 when the element is not contained.
(2) The chemical composition is mass%.
Nb: 0.003 to 3.000%,
Ti: 0.005 to 0.500%,
Ta: 0.001 to 0.500%,
V: 0.001 to 1.00%,
Cu: 0.001 to 3.00%,
Ni: 0.001 to 60.00%,
Cr: 0.001 to 30.00%,
Mo: 0.001 to 5.00%,
W: 0.001 to 2.00%,
B: 0.0001-0.0200%,
Co: 0.001 to 3.00%,
Be: 0.0003 to 0.050%,
Ag: 0.001 to 0.500%,
Ca: 0.0001-0.0500%,
Mg: 0.0001-0.0500%,
At least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc: 0.0001 to 0.5000% in total.
Sn: 0.001 to 0.300%,
Sb: 0.001 to 0.300%,
Te: 0.001 to 0.100%,
Se: 0.001 to 0.100%,
As: 0.001 to 0.050%,
Bi: 0.001 to 0.500%, and Pb: 0.001 to 0.500%
The steel material according to (1) above, which comprises one or more of the above.
(1)質量%で、
C:0.001~1.000%、
Si:0.01~3.00%、
Mn:0.10~4.50%、
P:0.300%以下、
S:0.0300%以下、
Al:0.001~5.000%、
N:0.2000%以下、
O:0.0100%以下、
Zr:0~0.8000%、及びHf:0~0.8000%からなる群より選択される少なくとも1種のZ元素、
Nb:0~3.000%、
Ti:0~0.500%、
Ta:0~0.500%、
V:0~1.00%、
Cu:0~3.00%、
Ni:0~60.00%、
Cr:0~30.00%、
Mo:0~5.00%、
W:0~2.00%、
B:0~0.0200%、
Co:0~3.00%、
Be:0~0.050%、
Ag:0~0.500%、
Ca:0~0.0500%、
Mg:0~0.0500%、
La、Ce、Nd、Y、Pm、Pr、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、及びScの少なくとも1種:合計で0~0.5000%、
Sn:0~0.300%、
Sb:0~0.300%、
Te:0~0.100%、
Se:0~0.100%、
As:0~0.050%、
Bi:0~0.500%、
Pb:0~0.500%、並びに
残部:Fe及び不純物からなり、
下記式1を満たす化学組成を有し、
結晶方位差が23~45°の粒界であって、Zr及びHfの偏析量の総和が0.2atoms/nm2以上である粒界を含む、鋼材。
0.61[Zr]+0.31[Hf]-1.75[O]-3.99[N]-1.74[S] ≧ 0.0003 ・・・式1
ここで、[Zr]、[Hf]、[O]、[N]、及び[S]は、各元素の含有量[質量%]であり、元素を含有しない場合は0である。
(2)前記化学組成が、質量%で、
Nb:0.003~3.000%、
Ti:0.005~0.500%、
Ta:0.001~0.500%、
V:0.001~1.00%、
Cu:0.001~3.00%、
Ni:0.001~60.00%、
Cr:0.001~30.00%、
Mo:0.001~5.00%、
W:0.001~2.00%、
B:0.0001~0.0200%、
Co:0.001~3.00%、
Be:0.0003~0.050%、
Ag:0.001~0.500%、
Ca:0.0001~0.0500%、
Mg:0.0001~0.0500%、
La、Ce、Nd、Y、Pm、Pr、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、及びScの少なくとも1種:合計で0.0001~0.5000%、
Sn:0.001~0.300%、
Sb:0.001~0.300%、
Te:0.001~0.100%、
Se:0.001~0.100%、
As:0.001~0.050%、
Bi:0.001~0.500%、並びに
Pb:0.001~0.500%
のうち1種又は2種以上を含む、上記(1)に記載の鋼材。 The steel materials that have achieved the above objectives are as follows.
(1) By mass%,
C: 0.001 to 1.000%,
Si: 0.01-3.00%,
Mn: 0.10 to 4.50%,
P: 0.300% or less,
S: 0.0300% or less,
Al: 0.001-5.000%,
N: 0.2000% or less,
O: 0.0100% or less,
At least one Z element selected from the group consisting of Zr: 0 to 0.8000% and Hf: 0 to 0.8000%.
Nb: 0-3.000%,
Ti: 0 to 0.500%,
Ta: 0 to 0.500%,
V: 0 to 1.00%,
Cu: 0 to 3.00%,
Ni: 0-60.00%,
Cr: 0 to 30.00%,
Mo: 0 to 5.00%,
W: 0 to 2.00%,
B: 0-0.0200%,
Co: 0 to 3.00%,
Be: 0 to 0.050%,
Ag: 0 to 0.500%,
Ca: 0-0.0500%,
Mg: 0-0.0500%,
At least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc: 0 to 0.5000% in total.
Sn: 0 to 0.300%,
Sb: 0 to 0.300%,
Te: 0 to 0.100%,
Se: 0 to 0.100%,
As: 0 to 0.050%,
Bi: 0 to 0.500%,
Pb: 0 to 0.500%, and the balance: Fe and impurities.
It has a chemical composition that satisfies the following formula 1 and has a chemical composition.
A steel material containing grain boundaries having a crystal orientation difference of 23 to 45 ° and a total segregation amount of Zr and Hf of 0.2 atoms / nm 2 or more.
0.61 [Zr] +0.31 [Hf] -1.75 [O] -3.99 [N] -1.74 [S] ≧ 0.0003 ・ ・ ・ Equation 1
Here, [Zr], [Hf], [O], [N], and [S] are the content [mass%] of each element, and are 0 when the element is not contained.
(2) The chemical composition is mass%.
Nb: 0.003 to 3.000%,
Ti: 0.005 to 0.500%,
Ta: 0.001 to 0.500%,
V: 0.001 to 1.00%,
Cu: 0.001 to 3.00%,
Ni: 0.001 to 60.00%,
Cr: 0.001 to 30.00%,
Mo: 0.001 to 5.00%,
W: 0.001 to 2.00%,
B: 0.0001-0.0200%,
Co: 0.001 to 3.00%,
Be: 0.0003 to 0.050%,
Ag: 0.001 to 0.500%,
Ca: 0.0001-0.0500%,
Mg: 0.0001-0.0500%,
At least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc: 0.0001 to 0.5000% in total.
Sn: 0.001 to 0.300%,
Sb: 0.001 to 0.300%,
Te: 0.001 to 0.100%,
Se: 0.001 to 0.100%,
As: 0.001 to 0.050%,
Bi: 0.001 to 0.500%, and Pb: 0.001 to 0.500%
The steel material according to (1) above, which comprises one or more of the above.
本発明によれば、鋼中のPの粒界偏析が低減された鋼材を提供することができる。
According to the present invention, it is possible to provide a steel material in which the grain boundary segregation of P in steel is reduced.
<鋼材>
本発明の実施形態に係る鋼材は、質量%で、
C:0.001~1.000%、
Si:0.01~3.00%、
Mn:0.10~4.50%、
P:0.300%以下、
S:0.0300%以下、
Al:0.001~5.000%、
N:0.2000%以下、
O:0.0100%以下、
Zr:0~0.8000%、及びHf:0~0.8000%からなる群より選択される少なくとも1種のZ元素、
Nb:0~3.000%、
Ti:0~0.500%、
Ta:0~0.500%、
V:0~1.00%、
Cu:0~3.00%、
Ni:0~60.00%、
Cr:0~30.00%、
Mo:0~5.00%、
W:0~2.00%、
B:0~0.0200%、
Co:0~3.00%、
Be:0~0.050%、
Ag:0~0.500%、
Ca:0~0.0500%、
Mg:0~0.0500%、
La、Ce、Nd、Y、Pm、Pr、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、及びScの少なくとも1種:合計で0~0.5000%、
Sn:0~0.300%、
Sb:0~0.300%、
Te:0~0.100%、
Se:0~0.100%、
As:0~0.050%、
Bi:0~0.500%、
Pb:0~0.500%、並びに
残部:Fe及び不純物からなり、
下記式1を満たす化学組成を有し、
結晶方位差が23~45°の粒界であって、Zr及びHfの偏析量の総和が0.2atoms/nm2以上である粒界を含むことを特徴としている。
0.61[Zr]+0.31[Hf]-1.75[O]-3.99[N]-1.74[S] ≧ 0.0003 ・・・式1
ここで、[Zr]、[Hf]、[O]、[N]、及び[S]は、各元素の含有量[質量%]であり、元素を含有しない場合は0である。 <Steel material>
The steel material according to the embodiment of the present invention is based on mass%.
C: 0.001 to 1.000%,
Si: 0.01-3.00%,
Mn: 0.10 to 4.50%,
P: 0.300% or less,
S: 0.0300% or less,
Al: 0.001-5.000%,
N: 0.2000% or less,
O: 0.0100% or less,
At least one Z element selected from the group consisting of Zr: 0 to 0.8000% and Hf: 0 to 0.8000%.
Nb: 0-3.000%,
Ti: 0 to 0.500%,
Ta: 0 to 0.500%,
V: 0 to 1.00%,
Cu: 0 to 3.00%,
Ni: 0-60.00%,
Cr: 0 to 30.00%,
Mo: 0 to 5.00%,
W: 0 to 2.00%,
B: 0-0.0200%,
Co: 0 to 3.00%,
Be: 0 to 0.050%,
Ag: 0 to 0.500%,
Ca: 0-0.0500%,
Mg: 0-0.0500%,
At least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc: 0 to 0.5000% in total.
Sn: 0 to 0.300%,
Sb: 0 to 0.300%,
Te: 0 to 0.100%,
Se: 0 to 0.100%,
As: 0 to 0.050%,
Bi: 0 to 0.500%,
Pb: 0 to 0.500%, and the balance: Fe and impurities.
It has a chemical composition that satisfies the following formula 1 and has a chemical composition.
It is characterized by including grain boundaries having a crystal orientation difference of 23 to 45 ° and a total segregation amount of Zr and Hf of 0.2 atoms / nm 2 or more.
0.61 [Zr] +0.31 [Hf] -1.75 [O] -3.99 [N] -1.74 [S] ≧ 0.0003 ・ ・ ・ Equation 1
Here, [Zr], [Hf], [O], [N], and [S] are the content [mass%] of each element, and are 0 when the element is not contained.
本発明の実施形態に係る鋼材は、質量%で、
C:0.001~1.000%、
Si:0.01~3.00%、
Mn:0.10~4.50%、
P:0.300%以下、
S:0.0300%以下、
Al:0.001~5.000%、
N:0.2000%以下、
O:0.0100%以下、
Zr:0~0.8000%、及びHf:0~0.8000%からなる群より選択される少なくとも1種のZ元素、
Nb:0~3.000%、
Ti:0~0.500%、
Ta:0~0.500%、
V:0~1.00%、
Cu:0~3.00%、
Ni:0~60.00%、
Cr:0~30.00%、
Mo:0~5.00%、
W:0~2.00%、
B:0~0.0200%、
Co:0~3.00%、
Be:0~0.050%、
Ag:0~0.500%、
Ca:0~0.0500%、
Mg:0~0.0500%、
La、Ce、Nd、Y、Pm、Pr、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、及びScの少なくとも1種:合計で0~0.5000%、
Sn:0~0.300%、
Sb:0~0.300%、
Te:0~0.100%、
Se:0~0.100%、
As:0~0.050%、
Bi:0~0.500%、
Pb:0~0.500%、並びに
残部:Fe及び不純物からなり、
下記式1を満たす化学組成を有し、
結晶方位差が23~45°の粒界であって、Zr及びHfの偏析量の総和が0.2atoms/nm2以上である粒界を含むことを特徴としている。
0.61[Zr]+0.31[Hf]-1.75[O]-3.99[N]-1.74[S] ≧ 0.0003 ・・・式1
ここで、[Zr]、[Hf]、[O]、[N]、及び[S]は、各元素の含有量[質量%]であり、元素を含有しない場合は0である。 <Steel material>
The steel material according to the embodiment of the present invention is based on mass%.
C: 0.001 to 1.000%,
Si: 0.01-3.00%,
Mn: 0.10 to 4.50%,
P: 0.300% or less,
S: 0.0300% or less,
Al: 0.001-5.000%,
N: 0.2000% or less,
O: 0.0100% or less,
At least one Z element selected from the group consisting of Zr: 0 to 0.8000% and Hf: 0 to 0.8000%.
Nb: 0-3.000%,
Ti: 0 to 0.500%,
Ta: 0 to 0.500%,
V: 0 to 1.00%,
Cu: 0 to 3.00%,
Ni: 0-60.00%,
Cr: 0 to 30.00%,
Mo: 0 to 5.00%,
W: 0 to 2.00%,
B: 0-0.0200%,
Co: 0 to 3.00%,
Be: 0 to 0.050%,
Ag: 0 to 0.500%,
Ca: 0-0.0500%,
Mg: 0-0.0500%,
At least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc: 0 to 0.5000% in total.
Sn: 0 to 0.300%,
Sb: 0 to 0.300%,
Te: 0 to 0.100%,
Se: 0 to 0.100%,
As: 0 to 0.050%,
Bi: 0 to 0.500%,
Pb: 0 to 0.500%, and the balance: Fe and impurities.
It has a chemical composition that satisfies the following formula 1 and has a chemical composition.
It is characterized by including grain boundaries having a crystal orientation difference of 23 to 45 ° and a total segregation amount of Zr and Hf of 0.2 atoms / nm 2 or more.
0.61 [Zr] +0.31 [Hf] -1.75 [O] -3.99 [N] -1.74 [S] ≧ 0.0003 ・ ・ ・ Equation 1
Here, [Zr], [Hf], [O], [N], and [S] are the content [mass%] of each element, and are 0 when the element is not contained.
鋼材の靭性、延性、耐食性及び溶接性などの特性を向上させるためには、鋼中のPの粒界偏析を低減することが重要である。例えば、高強度化のためにマルテンサイト及びベイナイトなどの組織を利用した鋼材においては、低温靭性を確保するため、焼入れ後に所定の温度で焼き戻し処理が行われる。このような焼き戻し処理の際に鋼中のPが旧オーステナイト粒界に偏析して、いわゆる焼き戻し脆化を引き起こし、その結果として鋼材の靭性を低下させることがある。これに関連して、鋼中のP含有量を低減すれば、それに応じて粒界に偏析するP量を低減することができるため、Pの粒界偏析に起因する焼き戻し脆化等の発生を抑制することが可能である。しかしながら、P含有量を過度に低減することは、精錬に時間を要し、生産性の低下や製造コストの大幅な上昇を招くという問題がある。
In order to improve the toughness, ductility, corrosion resistance and weldability of steel materials, it is important to reduce the grain boundary segregation of P in the steel. For example, in a steel material using a structure such as martensite and bainite for high strength, tempering treatment is performed at a predetermined temperature after quenching in order to secure low temperature toughness. During such tempering treatment, P in the steel may segregate at the old austenite grain boundaries, causing so-called tempering embrittlement, and as a result, the toughness of the steel material may be lowered. In relation to this, if the P content in the steel is reduced, the amount of P segregated at the grain boundaries can be reduced accordingly, so that tempering embrittlement due to the segregation of P grain boundaries occurs. Can be suppressed. However, excessively reducing the P content has a problem that it takes time for refining, which leads to a decrease in productivity and a significant increase in production cost.
そこで、本発明者らは、鋼中のPの粒界偏析を低減させることのできる元素について検討を行った。その結果、本発明者らは、鋼中に固溶している特定元素、すなわちZr及びHfの元素(以下、「Z元素」ともいう)の量をそれらの元素が鋼中で形成する介在物、より具体的にはこれらの元素の酸化物、窒化物及び硫化物との関係を考慮しつつ一定量以上確保し(すなわち、式1の左辺に対応する当該Z元素の有効量を0.0003%以上とし)、さらに当該Z元素を粒界に偏析させることでPの粒界偏析を低減することができることを見出した。
Therefore, the present inventors have investigated an element that can reduce the grain boundary segregation of P in steel. As a result, the present inventors have identified the amount of specific elements that are solid-dissolved in the steel, that is, the elements of Zr and Hf (hereinafter, also referred to as "Z element"), and the inclusions formed by these elements in the steel. More specifically, a certain amount or more is secured while considering the relationship between these elements with oxides, nitrides and sulfides (that is, the effective amount of the Z element corresponding to the left side of the formula 1 is 0.0003. % Or more), and further, it was found that the grain boundary segregation of P can be reduced by segregating the Z element at the grain boundary.
何ら特定の理論に束縛されることを意図するものではないが、上記のZ元素を粒界に偏析させることでPが偏析する粒界のサイトを少なくすることができ、その結果としてPの粒界偏析が低減されるか、又は当該Z元素の粒界偏析に付随して粒界に偏析する他の特定元素の作用によりPの粒界偏析が低減されるものと考えられる。しかしながら、上記のZ元素は、鋼中に存在するO(酸素)、N(窒素)及びS(硫黄)と結びついて、酸化物、窒化物及び硫化物からなる介在物を形成しやすいという性質を有する。Z元素が鋼中でこのような介在物を形成してしまうと、粒界に偏析することができるZ元素の固溶量が少なくなり、Pの粒界偏析を十分に低減することができなくなる。本発明においては、このような介在物を考慮したZ元素の固溶量を、後で詳しく説明する上記式1によって当該Z元素の有効量として算出しそして当該有効量を一定量以上、すなわち0.0003%以上確保することで、当該Z元素を粒界に十分な量において偏析させることができ、より具体的には当該Z元素を結晶方位差が23~45°の粒界に偏析量の総和が0.2atoms/nm2以上となるような量において偏析させることができ、それによってPの粒界偏析を顕著に抑制することが可能となる。したがって、本発明によれば、P含有量を過度に低減することなしに鋼中のPの粒界偏析が十分に低減された鋼材を得ることができるため、当該Pの粒界偏析に関連する鋼材の特性、例えば、靭性、延性、耐食性、溶接性などの特性を顕著に改善することが可能となる。粒界の結晶方位差23~45°は、必ずしもZ元素が偏析する粒界を限定するものではなく、Z元素は23~45°の結晶方位差以外の結晶方位差を有する粒界にも偏析し、それによってPの粒界偏析を抑制することが可能である。結晶方位差が23~45°の粒界は、マルテンサイト組織を有する鋼材の場合には旧オーステナイト粒界に相当する。したがって、このような結晶方位差を有する粒界におけるZ元素の偏析を促進することにより、例えばマルテンサイト組織を有する高強度鋼材の焼き戻し処理等の際にPが旧オーステナイト粒界に偏析することを抑制することができる。その結果として、本発明によれば、焼き戻し脆化等の発生を抑制することができ、それゆえ鋼材の靭性等の特性を顕著に向上させることが可能となる。
Although not intended to be bound by any particular theory, by segregating the above Z element at the grain boundaries, it is possible to reduce the number of grain boundary sites where P segregates, and as a result, the grains of P. It is considered that the boundary segregation is reduced, or the grain boundary segregation of P is reduced by the action of other specific elements that segregate at the grain boundaries accompanying the grain boundary segregation of the Z element. However, the above-mentioned element Z has the property of easily forming inclusions composed of oxides, nitrides and sulfides in combination with O (oxygen), N (nitrogen) and S (sulfur) existing in the steel. Have. If the Z element forms such inclusions in the steel, the amount of solid solution of the Z element that can be segregated at the grain boundaries is reduced, and the grain boundary segregation of P cannot be sufficiently reduced. .. In the present invention, the solid solution amount of the Z element in consideration of such inclusions is calculated as the effective amount of the Z element by the above formula 1 which will be described in detail later, and the effective amount is set to a certain amount or more, that is, 0. By securing .0003% or more, the Z element can be segregated at the grain boundary in a sufficient amount, and more specifically, the Z element is segregated at the grain boundary having a crystal orientation difference of 23 to 45 °. Segregation can be performed in an amount such that the total sum is 0.2 atoms / nm 2 or more, whereby the grain boundary segregation of P can be remarkably suppressed. Therefore, according to the present invention, it is possible to obtain a steel material in which the grain boundary segregation of P in the steel is sufficiently reduced without excessively reducing the P content, which is related to the grain boundary segregation of P. It is possible to remarkably improve the characteristics of the steel material, for example, the characteristics such as toughness, ductility, corrosion resistance, and weldability. The grain boundary crystal orientation difference of 23 to 45 ° does not necessarily limit the grain boundary where the Z element segregates, and the Z element segregates to the grain boundary having a crystal orientation difference other than the crystal orientation difference of 23 to 45 °. However, it is possible to suppress the grain boundary segregation of P. The grain boundaries having a crystal orientation difference of 23 to 45 ° correspond to the former austenite grain boundaries in the case of a steel material having a martensite structure. Therefore, by promoting the segregation of the Z element at the grain boundaries having such a crystal orientation difference, P segregates into the old austenite grain boundaries, for example, during the tempering treatment of a high-strength steel material having a martensite structure. Can be suppressed. As a result, according to the present invention, it is possible to suppress the occurrence of tempering embrittlement and the like, and therefore it is possible to significantly improve the toughness and other properties of the steel material.
本発明におけるZ元素は、上記のとおりO、N及びSと結びついて介在物を形成しやすく、それゆえ鋼中で所定の固溶量を確保することは一般に困難である。このような事情から、上記Z元素によるPの粒界偏析の低減効果は従来知られていなかった。しかしながら、近年の精錬技術の進歩により、一般に不純物として鋼中に存在するO、N及びSなどの元素の含有量を非常に低いレベルにまで低減することが可能となったこともあり、今回、上記Z元素の所定範囲内における固溶を実現することができた。したがって、上記Z元素に関するPの粒界偏析低減効果は、今回、本発明者らによって初めて明らかにされたことであり、極めて意外であり、また驚くべきことである。
The Z element in the present invention easily combines with O, N and S to form inclusions as described above, and therefore it is generally difficult to secure a predetermined solid solution amount in steel. Under these circumstances, the effect of reducing the grain boundary segregation of P by the Z element has not been known so far. However, recent advances in refining technology have made it possible to reduce the content of elements such as O, N, and S, which are generally present in steel as impurities, to extremely low levels. It was possible to realize a solid solution within a predetermined range of the Z element. Therefore, the effect of reducing the grain boundary segregation of P on the Z element has been clarified for the first time by the present inventors, and is extremely surprising and surprising.
以下、本発明の実施形態に係る鋼材についてより詳しく説明する。以下の説明において、各元素の含有量の単位である「%」は、特に断りがない限り「質量%」を意味するものである。また、本明細書において、数値範囲を示す「~」とは、特に断りがない場合、その前後に記載される数値を下限値及び上限値として含む意味で使用される。
Hereinafter, the steel material according to the embodiment of the present invention will be described in more detail. In the following description, "%", which is a unit of the content of each element, means "mass%" unless otherwise specified. Further, in the present specification, "-" indicating a numerical range is used to mean that the numerical values described before and after the numerical range are included as the lower limit value and the upper limit value unless otherwise specified.
[C:0.001~1.000%]
炭素(C)は、硬さの安定化及び/又は強度の確保に必要な元素である。これらの効果を十分に得るために、C含有量は0.001%以上である。C含有量は0.005%以上、0.010%以上又は0.020%以上であってもよい。一方で、Cを過度に含有すると、靭性、曲げ性及び/又は溶接性が低下する場合がある。したがって、C含有量は1.000%以下である。C含有量は0.800%以下、0.600%以下又は0.500%以下であってもよい。 [C: 0.001 to 1.000%]
Carbon (C) is an element necessary for stabilizing hardness and / or ensuring strength. In order to sufficiently obtain these effects, the C content is 0.001% or more. The C content may be 0.005% or more, 0.010% or more, or 0.020% or more. On the other hand, if C is excessively contained, toughness, bendability and / or weldability may decrease. Therefore, the C content is 1.000% or less. The C content may be 0.800% or less, 0.600% or less, or 0.500% or less.
炭素(C)は、硬さの安定化及び/又は強度の確保に必要な元素である。これらの効果を十分に得るために、C含有量は0.001%以上である。C含有量は0.005%以上、0.010%以上又は0.020%以上であってもよい。一方で、Cを過度に含有すると、靭性、曲げ性及び/又は溶接性が低下する場合がある。したがって、C含有量は1.000%以下である。C含有量は0.800%以下、0.600%以下又は0.500%以下であってもよい。 [C: 0.001 to 1.000%]
Carbon (C) is an element necessary for stabilizing hardness and / or ensuring strength. In order to sufficiently obtain these effects, the C content is 0.001% or more. The C content may be 0.005% or more, 0.010% or more, or 0.020% or more. On the other hand, if C is excessively contained, toughness, bendability and / or weldability may decrease. Therefore, the C content is 1.000% or less. The C content may be 0.800% or less, 0.600% or less, or 0.500% or less.
[Si:0.01~3.00%]
ケイ素(Si)は脱酸元素であり、強度の向上にも寄与する元素である。これらの効果を十分に得るために、Si含有量は0.01%以上である。Si含有量は0.05%以上、0.10%以上又は0.30%以上であってもよい。一方で、Siを過度に含有すると、靭性が低下したり、スケール疵と呼ばれる表面品質不良を発生したりする場合がある。したがって、Si含有量は3.00%以下である。Si含有量は2.00%以下、1.00%以下又は0.60%以下であってもよい。 [Si: 0.01 to 3.00%]
Silicon (Si) is a deoxidizing element and is an element that also contributes to the improvement of strength. In order to sufficiently obtain these effects, the Si content is 0.01% or more. The Si content may be 0.05% or more, 0.10% or more, or 0.30% or more. On the other hand, if Si is excessively contained, the toughness may be lowered or surface quality defects called scale defects may occur. Therefore, the Si content is 3.00% or less. The Si content may be 2.00% or less, 1.00% or less, or 0.60% or less.
ケイ素(Si)は脱酸元素であり、強度の向上にも寄与する元素である。これらの効果を十分に得るために、Si含有量は0.01%以上である。Si含有量は0.05%以上、0.10%以上又は0.30%以上であってもよい。一方で、Siを過度に含有すると、靭性が低下したり、スケール疵と呼ばれる表面品質不良を発生したりする場合がある。したがって、Si含有量は3.00%以下である。Si含有量は2.00%以下、1.00%以下又は0.60%以下であってもよい。 [Si: 0.01 to 3.00%]
Silicon (Si) is a deoxidizing element and is an element that also contributes to the improvement of strength. In order to sufficiently obtain these effects, the Si content is 0.01% or more. The Si content may be 0.05% or more, 0.10% or more, or 0.30% or more. On the other hand, if Si is excessively contained, the toughness may be lowered or surface quality defects called scale defects may occur. Therefore, the Si content is 3.00% or less. The Si content may be 2.00% or less, 1.00% or less, or 0.60% or less.
[Mn:0.10~4.50%]
マンガン(Mn)は、焼入れ性及び/又は強度の向上に有効な元素であり、有効なオーステナイト安定化元素でもある。これらの効果を十分に得るために、Mn含有量は0.10%以上である。Mn含有量は0.50%以上、0.70%以上又は1.00%以上であってもよい。一方で、Mnを過度に含有すると、靭性に有害なMnSが生成したり、耐酸化性を低下させたりする場合がある。したがって、Mn含有量は4.50%以下である。Mn含有量は4.00%以下、3.50%以下又は3.00%以下であってもよい。 [Mn: 0.10 to 4.50%]
Manganese (Mn) is an element effective for improving hardenability and / or strength, and is also an effective austenite stabilizing element. In order to sufficiently obtain these effects, the Mn content is 0.10% or more. The Mn content may be 0.50% or more, 0.70% or more, or 1.00% or more. On the other hand, if Mn is excessively contained, MnS harmful to toughness may be generated or the oxidation resistance may be lowered. Therefore, the Mn content is 4.50% or less. The Mn content may be 4.00% or less, 3.50% or less, or 3.00% or less.
マンガン(Mn)は、焼入れ性及び/又は強度の向上に有効な元素であり、有効なオーステナイト安定化元素でもある。これらの効果を十分に得るために、Mn含有量は0.10%以上である。Mn含有量は0.50%以上、0.70%以上又は1.00%以上であってもよい。一方で、Mnを過度に含有すると、靭性に有害なMnSが生成したり、耐酸化性を低下させたりする場合がある。したがって、Mn含有量は4.50%以下である。Mn含有量は4.00%以下、3.50%以下又は3.00%以下であってもよい。 [Mn: 0.10 to 4.50%]
Manganese (Mn) is an element effective for improving hardenability and / or strength, and is also an effective austenite stabilizing element. In order to sufficiently obtain these effects, the Mn content is 0.10% or more. The Mn content may be 0.50% or more, 0.70% or more, or 1.00% or more. On the other hand, if Mn is excessively contained, MnS harmful to toughness may be generated or the oxidation resistance may be lowered. Therefore, the Mn content is 4.50% or less. The Mn content may be 4.00% or less, 3.50% or less, or 3.00% or less.
[P:0.300%以下]
リン(P)は製造工程で混入する元素である。鋼中のPの粒界偏析を低減するという観点からはPは少ないほど好ましく、よってP含有量は0%であってもよい。しかしながら、P含有量を0.0001%未満に低減するためには精錬に時間を要し、生産性の低下を招く。したがって、P含有量は0.0001%以上、0.0005%以上、0.001%以上、0.003%以上、又は、0.005%以上であってもよい。P含有量は、製造コストの観点から、0.007%以上であってもよい。一方で、Pを過度に含有すると、Pの粒界偏析量が増加し、鋼材の種々の特性、例えば靭性、延性、耐食性及び/又は溶接性などの特性が低下する場合がある。したがって、P含有量は0.300%以下である。P含有量は0.100%以下、0.030%以下又は0.010%以下であってもよい。 [P: 0.300% or less]
Phosphorus (P) is an element mixed in the manufacturing process. From the viewpoint of reducing the grain boundary segregation of P in the steel, the smaller the P, the more preferable, and the P content may be 0%. However, in order to reduce the P content to less than 0.0001%, it takes time for refining, which leads to a decrease in productivity. Therefore, the P content may be 0.0001% or more, 0.0005% or more, 0.001% or more, 0.003% or more, or 0.005% or more. The P content may be 0.007% or more from the viewpoint of manufacturing cost. On the other hand, if P is excessively contained, the grain boundary segregation amount of P may increase, and various properties of the steel material such as toughness, ductility, corrosion resistance and / or weldability may deteriorate. Therefore, the P content is 0.300% or less. The P content may be 0.100% or less, 0.030% or less, or 0.010% or less.
リン(P)は製造工程で混入する元素である。鋼中のPの粒界偏析を低減するという観点からはPは少ないほど好ましく、よってP含有量は0%であってもよい。しかしながら、P含有量を0.0001%未満に低減するためには精錬に時間を要し、生産性の低下を招く。したがって、P含有量は0.0001%以上、0.0005%以上、0.001%以上、0.003%以上、又は、0.005%以上であってもよい。P含有量は、製造コストの観点から、0.007%以上であってもよい。一方で、Pを過度に含有すると、Pの粒界偏析量が増加し、鋼材の種々の特性、例えば靭性、延性、耐食性及び/又は溶接性などの特性が低下する場合がある。したがって、P含有量は0.300%以下である。P含有量は0.100%以下、0.030%以下又は0.010%以下であってもよい。 [P: 0.300% or less]
Phosphorus (P) is an element mixed in the manufacturing process. From the viewpoint of reducing the grain boundary segregation of P in the steel, the smaller the P, the more preferable, and the P content may be 0%. However, in order to reduce the P content to less than 0.0001%, it takes time for refining, which leads to a decrease in productivity. Therefore, the P content may be 0.0001% or more, 0.0005% or more, 0.001% or more, 0.003% or more, or 0.005% or more. The P content may be 0.007% or more from the viewpoint of manufacturing cost. On the other hand, if P is excessively contained, the grain boundary segregation amount of P may increase, and various properties of the steel material such as toughness, ductility, corrosion resistance and / or weldability may deteriorate. Therefore, the P content is 0.300% or less. The P content may be 0.100% or less, 0.030% or less, or 0.010% or less.
[S:0.0300%以下]
硫黄(S)は製造工程で混入する元素であり、本発明の実施形態に係るZ元素との間で形成される介在物を低減する観点からは少ないほど好ましく、よってS含有量は0%であってもよい。しかしながら、S含有量を0.0001%未満に低減するためには精錬に時間を要し、生産性の低下を招く。したがって、S含有量は0.0001%以上、0.0005%以上又は0.0010%以上であってもよい。一方で、Sを過度に含有すると、Z元素の有効量が低下するとともに、靭性が低下する場合がある。したがって、S含有量は0.0300%以下である。S含有量は好ましくは0.0100%以下、より好ましくは0.0050%以下、最も好ましくは0.0030%以下である。 [S: 0.0300% or less]
Sulfur (S) is an element mixed in the manufacturing process, and is preferable from the viewpoint of reducing inclusions formed with the Z element according to the embodiment of the present invention, so that the S content is 0%. There may be. However, in order to reduce the S content to less than 0.0001%, it takes time for refining, which leads to a decrease in productivity. Therefore, the S content may be 0.0001% or more, 0.0005% or more, or 0.0010% or more. On the other hand, if S is excessively contained, the effective amount of the Z element may decrease and the toughness may decrease. Therefore, the S content is 0.0300% or less. The S content is preferably 0.0100% or less, more preferably 0.0050% or less, and most preferably 0.0030% or less.
硫黄(S)は製造工程で混入する元素であり、本発明の実施形態に係るZ元素との間で形成される介在物を低減する観点からは少ないほど好ましく、よってS含有量は0%であってもよい。しかしながら、S含有量を0.0001%未満に低減するためには精錬に時間を要し、生産性の低下を招く。したがって、S含有量は0.0001%以上、0.0005%以上又は0.0010%以上であってもよい。一方で、Sを過度に含有すると、Z元素の有効量が低下するとともに、靭性が低下する場合がある。したがって、S含有量は0.0300%以下である。S含有量は好ましくは0.0100%以下、より好ましくは0.0050%以下、最も好ましくは0.0030%以下である。 [S: 0.0300% or less]
Sulfur (S) is an element mixed in the manufacturing process, and is preferable from the viewpoint of reducing inclusions formed with the Z element according to the embodiment of the present invention, so that the S content is 0%. There may be. However, in order to reduce the S content to less than 0.0001%, it takes time for refining, which leads to a decrease in productivity. Therefore, the S content may be 0.0001% or more, 0.0005% or more, or 0.0010% or more. On the other hand, if S is excessively contained, the effective amount of the Z element may decrease and the toughness may decrease. Therefore, the S content is 0.0300% or less. The S content is preferably 0.0100% or less, more preferably 0.0050% or less, and most preferably 0.0030% or less.
[Al:0.001~5.000%]
アルミニウム(Al)は、脱酸元素であり、耐食性及び/又は耐熱性を向上させるのに有効な元素でもある。これらの効果を得るために、Al含有量は0.001%以上である。Al含有量は0.010%以上、0.100%以上又は0.200%以上であってもよい。とりわけ、耐熱性を十分に向上させる観点からは、Al含有量は1.000%以上、2.000%以上又は3.000%以上であってもよい。一方で、Alを過度に含有すると、粗大な介在物が生成して靭性を低下させたり、製造過程で割れなどのトラブルが発生したり、及び/又は耐疲労特性を低下させたりする場合がある。したがって、Al含有量は5.000%以下である。Al含有量は4.500%以下、4.000%以下又は3.500%以下であってもよい。とりわけ、靭性の低下を抑制するという観点からは、Al含有量は1.500%以下、1.000%以下又は0.300%以下であってもよい。 [Al: 0.001-5.000%]
Aluminum (Al) is a deoxidizing element and is also an effective element for improving corrosion resistance and / or heat resistance. In order to obtain these effects, the Al content is 0.001% or more. The Al content may be 0.010% or more, 0.100% or more, or 0.200% or more. In particular, from the viewpoint of sufficiently improving the heat resistance, the Al content may be 1.000% or more, 2.000% or more, or 3.000% or more. On the other hand, if Al is excessively contained, coarse inclusions may be generated to reduce toughness, troubles such as cracking may occur in the manufacturing process, and / or fatigue resistance may be deteriorated. .. Therefore, the Al content is 5.000% or less. The Al content may be 4.500% or less, 4000% or less, or 3.500% or less. In particular, from the viewpoint of suppressing the decrease in toughness, the Al content may be 1.500% or less, 1.000% or less, or 0.300% or less.
アルミニウム(Al)は、脱酸元素であり、耐食性及び/又は耐熱性を向上させるのに有効な元素でもある。これらの効果を得るために、Al含有量は0.001%以上である。Al含有量は0.010%以上、0.100%以上又は0.200%以上であってもよい。とりわけ、耐熱性を十分に向上させる観点からは、Al含有量は1.000%以上、2.000%以上又は3.000%以上であってもよい。一方で、Alを過度に含有すると、粗大な介在物が生成して靭性を低下させたり、製造過程で割れなどのトラブルが発生したり、及び/又は耐疲労特性を低下させたりする場合がある。したがって、Al含有量は5.000%以下である。Al含有量は4.500%以下、4.000%以下又は3.500%以下であってもよい。とりわけ、靭性の低下を抑制するという観点からは、Al含有量は1.500%以下、1.000%以下又は0.300%以下であってもよい。 [Al: 0.001-5.000%]
Aluminum (Al) is a deoxidizing element and is also an effective element for improving corrosion resistance and / or heat resistance. In order to obtain these effects, the Al content is 0.001% or more. The Al content may be 0.010% or more, 0.100% or more, or 0.200% or more. In particular, from the viewpoint of sufficiently improving the heat resistance, the Al content may be 1.000% or more, 2.000% or more, or 3.000% or more. On the other hand, if Al is excessively contained, coarse inclusions may be generated to reduce toughness, troubles such as cracking may occur in the manufacturing process, and / or fatigue resistance may be deteriorated. .. Therefore, the Al content is 5.000% or less. The Al content may be 4.500% or less, 4000% or less, or 3.500% or less. In particular, from the viewpoint of suppressing the decrease in toughness, the Al content may be 1.500% or less, 1.000% or less, or 0.300% or less.
[N:0.2000%以下]
窒素(N)は製造工程で混入する元素であり、本発明の実施形態に係るZ元素との間で形成される介在物を低減する観点からは少ないほど好ましく、よってN含有量は0%であってもよい。しかしながら、N含有量を0.0001%未満に低減するためには精錬に時間を要し、生産性の低下を招く。したがって、N含有量は0.0001%以上、0.0005%以上又は0.0010%以上であってもよい。一方で、Nはオーステナイトの安定化に有効な元素でもあり、必要に応じて意図的に含有させてもよい。この場合には、N含有量は0.0100%以上であることが好ましく、0.0200%以上、0.0500%以上であってもよい。しかしながら、Nを過度に含有すると、Z元素の有効量が低下するとともに、靭性が低下する場合がある。したがって、N含有量は0.2000%以下である。N含有量は0.1500%以下、0.1000%以下又は0.0800%以下であってもよい。 [N: 0.2000% or less]
Nitrogen (N) is an element mixed in the manufacturing process, and is preferable from the viewpoint of reducing inclusions formed with the Z element according to the embodiment of the present invention, so that the N content is 0%. There may be. However, in order to reduce the N content to less than 0.0001%, it takes time for refining, which leads to a decrease in productivity. Therefore, the N content may be 0.0001% or more, 0.0005% or more, or 0.0010% or more. On the other hand, N is also an element effective for stabilizing austenite, and may be intentionally contained if necessary. In this case, the N content is preferably 0.0100% or more, and may be 0.0200% or more and 0.0500% or more. However, if N is excessively contained, the effective amount of the Z element may decrease and the toughness may decrease. Therefore, the N content is 0.2000% or less. The N content may be 0.1500% or less, 0.1000% or less, or 0.0800% or less.
窒素(N)は製造工程で混入する元素であり、本発明の実施形態に係るZ元素との間で形成される介在物を低減する観点からは少ないほど好ましく、よってN含有量は0%であってもよい。しかしながら、N含有量を0.0001%未満に低減するためには精錬に時間を要し、生産性の低下を招く。したがって、N含有量は0.0001%以上、0.0005%以上又は0.0010%以上であってもよい。一方で、Nはオーステナイトの安定化に有効な元素でもあり、必要に応じて意図的に含有させてもよい。この場合には、N含有量は0.0100%以上であることが好ましく、0.0200%以上、0.0500%以上であってもよい。しかしながら、Nを過度に含有すると、Z元素の有効量が低下するとともに、靭性が低下する場合がある。したがって、N含有量は0.2000%以下である。N含有量は0.1500%以下、0.1000%以下又は0.0800%以下であってもよい。 [N: 0.2000% or less]
Nitrogen (N) is an element mixed in the manufacturing process, and is preferable from the viewpoint of reducing inclusions formed with the Z element according to the embodiment of the present invention, so that the N content is 0%. There may be. However, in order to reduce the N content to less than 0.0001%, it takes time for refining, which leads to a decrease in productivity. Therefore, the N content may be 0.0001% or more, 0.0005% or more, or 0.0010% or more. On the other hand, N is also an element effective for stabilizing austenite, and may be intentionally contained if necessary. In this case, the N content is preferably 0.0100% or more, and may be 0.0200% or more and 0.0500% or more. However, if N is excessively contained, the effective amount of the Z element may decrease and the toughness may decrease. Therefore, the N content is 0.2000% or less. The N content may be 0.1500% or less, 0.1000% or less, or 0.0800% or less.
[O:0.0100%以下]
酸素(O)は製造工程で混入する元素であり、本発明の実施形態に係るZ元素との間で形成される介在物を低減する観点からは少ないほど好ましく、よってO含有量は0%であってもよい。しかしながら、O含有量を0.0001%未満に低減するためには精錬に時間を要し、生産性の低下を招く。したがって、O含有量は0.0001%以上、0.0005%以上又は0.0010%以上であってもよい。一方で、Oを過度に含有すると、粗大な介在物が形成され、Z元素の有効量が低下するとともに、鋼材の成形性及び/又は靭性が低下する場合がある。したがって、O含有量は0.0100%以下である。O含有量は0.0080%以下、0.0060%以下又は0.0040%以下であってもよい。 [O: 0.0100% or less]
Oxygen (O) is an element mixed in the manufacturing process, and is preferable from the viewpoint of reducing inclusions formed with the Z element according to the embodiment of the present invention, so that the O content is 0%. There may be. However, in order to reduce the O content to less than 0.0001%, it takes time for refining, which leads to a decrease in productivity. Therefore, the O content may be 0.0001% or more, 0.0005% or more, or 0.0010% or more. On the other hand, if O is excessively contained, coarse inclusions may be formed, the effective amount of the Z element may be lowered, and the formability and / or toughness of the steel material may be lowered. Therefore, the O content is 0.0100% or less. The O content may be 0.0080% or less, 0.0060% or less, or 0.0040% or less.
酸素(O)は製造工程で混入する元素であり、本発明の実施形態に係るZ元素との間で形成される介在物を低減する観点からは少ないほど好ましく、よってO含有量は0%であってもよい。しかしながら、O含有量を0.0001%未満に低減するためには精錬に時間を要し、生産性の低下を招く。したがって、O含有量は0.0001%以上、0.0005%以上又は0.0010%以上であってもよい。一方で、Oを過度に含有すると、粗大な介在物が形成され、Z元素の有効量が低下するとともに、鋼材の成形性及び/又は靭性が低下する場合がある。したがって、O含有量は0.0100%以下である。O含有量は0.0080%以下、0.0060%以下又は0.0040%以下であってもよい。 [O: 0.0100% or less]
Oxygen (O) is an element mixed in the manufacturing process, and is preferable from the viewpoint of reducing inclusions formed with the Z element according to the embodiment of the present invention, so that the O content is 0%. There may be. However, in order to reduce the O content to less than 0.0001%, it takes time for refining, which leads to a decrease in productivity. Therefore, the O content may be 0.0001% or more, 0.0005% or more, or 0.0010% or more. On the other hand, if O is excessively contained, coarse inclusions may be formed, the effective amount of the Z element may be lowered, and the formability and / or toughness of the steel material may be lowered. Therefore, the O content is 0.0100% or less. The O content may be 0.0080% or less, 0.0060% or less, or 0.0040% or less.
[Zr:0~0.8000%、及びHf:0~0.8000%からなる群より選択される少なくとも1種のZ元素]
本発明の実施形態に係るZ元素は、Zr:0~0.8000%、及びHf:0~0.8000%であり、ジルコニウム(Zr)及びハフニウム(Hf)は鋼中に固溶状態で存在することにより、これらのZ元素の粒界偏析に基づくPの粒界偏析低減効果を発現することができる。当該Pの粒界偏析低減効果を発現することで、当該Pの粒界偏析に関連する鋼材の特性、例えば、靭性、延性、耐食性、溶接性などの特性を顕著に改善することが可能となる。 [At least one Z element selected from the group consisting of Zr: 0 to 0.8000% and Hf: 0 to 0.8000%]
The Z element according to the embodiment of the present invention is Zr: 0 to 0.8000% and Hf: 0 to 0.8000%, and zirconium (Zr) and hafnium (Hf) are present in the steel in a solid solution state. By doing so, it is possible to exhibit the effect of reducing the grain boundary segregation of P based on the grain boundary segregation of these Z elements. By exhibiting the effect of reducing the grain boundary segregation of P, it becomes possible to remarkably improve the characteristics of the steel material related to the grain boundary segregation of P, such as toughness, ductility, corrosion resistance, and weldability. ..
本発明の実施形態に係るZ元素は、Zr:0~0.8000%、及びHf:0~0.8000%であり、ジルコニウム(Zr)及びハフニウム(Hf)は鋼中に固溶状態で存在することにより、これらのZ元素の粒界偏析に基づくPの粒界偏析低減効果を発現することができる。当該Pの粒界偏析低減効果を発現することで、当該Pの粒界偏析に関連する鋼材の特性、例えば、靭性、延性、耐食性、溶接性などの特性を顕著に改善することが可能となる。 [At least one Z element selected from the group consisting of Zr: 0 to 0.8000% and Hf: 0 to 0.8000%]
The Z element according to the embodiment of the present invention is Zr: 0 to 0.8000% and Hf: 0 to 0.8000%, and zirconium (Zr) and hafnium (Hf) are present in the steel in a solid solution state. By doing so, it is possible to exhibit the effect of reducing the grain boundary segregation of P based on the grain boundary segregation of these Z elements. By exhibiting the effect of reducing the grain boundary segregation of P, it becomes possible to remarkably improve the characteristics of the steel material related to the grain boundary segregation of P, such as toughness, ductility, corrosion resistance, and weldability. ..
上記Z元素は、いずれか1つの元素を単独で使用してもよいし、又は両方を使用してもよい。また、当該Z元素は、後で詳しく説明する式1を満たす量において存在すればよく、その下限値は特に限定されない。しかしながら、例えば、各Z元素の含有量又は合計の含有量は0.0010%以上であってもよく、好ましくは0.0050%以上であり、より好ましくは0.0150%以上であり、さらにより好ましくは0.0300%以上であり、最も好ましくは0.0500%以上である。一方で、Z元素を過度に含有しても効果が飽和し、それゆえ当該Z元素を必要以上に鋼材中に含有させることは製造コストの上昇を招く虞がある。したがって、各Z元素の含有量は0.8000%以下であり、例えば0.7000%以下、0.6000%以下、0.5000%以下、0.4000%以下又は0.3000%以下であってもよい。また、Z元素の含有量の合計は1.6000%以下であり、例えば1.2000%以下、1.0000%以下、0.8000%以下、0.6000%以下又は0.5000%以下であってもよい。
As the Z element, any one element may be used alone, or both may be used. Further, the Z element may be present in an amount satisfying Equation 1, which will be described in detail later, and the lower limit thereof is not particularly limited. However, for example, the content of each Z element or the total content may be 0.0010% or more, preferably 0.0050% or more, more preferably 0.0150% or more, and even more. It is preferably 0.0300% or more, and most preferably 0.0500% or more. On the other hand, even if the Z element is excessively contained, the effect is saturated, and therefore, if the Z element is contained in the steel material more than necessary, the manufacturing cost may increase. Therefore, the content of each Z element is 0.8000% or less, for example, 0.7000% or less, 0.6000% or less, 0.5000% or less, 0.4000% or less, or 0.3000% or less. May be good. The total content of the Z element is 1.6000% or less, for example, 1.2000% or less, 1.000% or less, 0.8000% or less, 0.6000% or less, or 0.5000% or less. You may.
本発明の実施形態に係る鋼材の基本化学組成は上記のとおりである。さらに、当該鋼材は、必要に応じて以下の任意選択元素のうち1種又は2種以上を含有してもよい。例えば、鋼材は、Nb:0~3.000%、Ti:0~0.500%、Ta:0~0.500%、V:0~1.00%、Cu:0~3.00%、Ni:0~60.00%、Cr:0~30.00%、Mo:0~5.00%、W:0~2.00%、B:0~0.0200%、Co:0~3.00%、Be:0~0.050%、及びAg:0~0.500%のうち1種又は2種以上を含有してもよい。また、鋼材は、Ca:0~0.0500%、Mg:0~0.0500%、並びにLa、Ce、Nd、Y、Pm、Pr、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、及びScの少なくとも1種:合計で0~0.5000%のうち1種又は2種以上を含有してもよい。また、鋼材は、Sn:0~0.300%、及びSb:0~0.300%のうち1種又は2種を含有してもよい。また、鋼材は、Te:0~0.100%、Se:0~0.100%、As:0~0.050%、Bi:0~0.500%、及びPb:0~0.500%のうち1種又は2種以上を含有してもよい。以下、これらの任意選択元素について詳しく説明する。
The basic chemical composition of the steel material according to the embodiment of the present invention is as described above. Further, the steel material may contain one or more of the following optional elements, if necessary. For example, the steel material has Nb: 0 to 3.000%, Ti: 0 to 0.500%, Ta: 0 to 0.500%, V: 0 to 1.00%, Cu: 0 to 3.00%, Ni: 0 to 60.00%, Cr: 0 to 30.00%, Mo: 0 to 5.00%, W: 0 to 2.00%, B: 0 to 0.0200%, Co: 0 to 3 It may contain one or more of 0.00%, Be: 0 to 0.050%, and Ag: 0 to 0.500%. The steel materials include Ca: 0 to 0.0500%, Mg: 0 to 0.0500%, and La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er. At least one of Tm, Yb, Lu, and Sc: one or more of 0 to 0.5000% in total may be contained. Further, the steel material may contain one or two of Sn: 0 to 0.300% and Sb: 0 to 0.300%. The steel materials are Te: 0 to 0.100%, Se: 0 to 0.100%, As: 0 to 0.050%, Bi: 0 to 0.500%, and Pb: 0 to 0.500%. One or more of them may be contained. Hereinafter, these optional elements will be described in detail.
[Nb:0~3.000%]
ニオブ(Nb)は、析出強化及び再結晶の抑制等に寄与する元素である。Nb含有量は0%であってもよいが、これらの効果を得るためには、Nb含有量は0.003%以上であることが好ましい。例えば、Nb含有量は0.005%以上又は0.010%以上であってもよい。とりわけ、析出強化を十分に図る観点からは、Nb含有量は1.000%以上又は1.500%以上であってもよい。一方で、Nbを過度に含有すると、効果が飽和し、加工性及び/又は靭性を低下させる場合がある。したがって、Nb含有量は3.000%以下である。Nb含有量は2.800%以下、2.500%以下又は2.000%以下であってもよい。とりわけ、溶接熱影響部(HAZ)の靭性低下を抑制するという観点からは、Nb含有量は0.100%以下であることが好ましく、0.080%以下、0.050%以下又は0.030%以下であってもよい。 [Nb: 0-3.000%]
Niobium (Nb) is an element that contributes to strengthening precipitation and suppressing recrystallization. The Nb content may be 0%, but in order to obtain these effects, the Nb content is preferably 0.003% or more. For example, the Nb content may be 0.005% or more or 0.010% or more. In particular, the Nb content may be 1.000% or more or 1.500% or more from the viewpoint of sufficiently strengthening precipitation. On the other hand, if Nb is excessively contained, the effect may be saturated and the processability and / or toughness may be lowered. Therefore, the Nb content is 3.000% or less. The Nb content may be 2.800% or less, 2.500% or less, or 2.000% or less. In particular, from the viewpoint of suppressing the decrease in toughness of the weld heat affected zone (HAZ), the Nb content is preferably 0.100% or less, 0.080% or less, 0.050% or less, or 0.030. It may be less than or equal to%.
ニオブ(Nb)は、析出強化及び再結晶の抑制等に寄与する元素である。Nb含有量は0%であってもよいが、これらの効果を得るためには、Nb含有量は0.003%以上であることが好ましい。例えば、Nb含有量は0.005%以上又は0.010%以上であってもよい。とりわけ、析出強化を十分に図る観点からは、Nb含有量は1.000%以上又は1.500%以上であってもよい。一方で、Nbを過度に含有すると、効果が飽和し、加工性及び/又は靭性を低下させる場合がある。したがって、Nb含有量は3.000%以下である。Nb含有量は2.800%以下、2.500%以下又は2.000%以下であってもよい。とりわけ、溶接熱影響部(HAZ)の靭性低下を抑制するという観点からは、Nb含有量は0.100%以下であることが好ましく、0.080%以下、0.050%以下又は0.030%以下であってもよい。 [Nb: 0-3.000%]
Niobium (Nb) is an element that contributes to strengthening precipitation and suppressing recrystallization. The Nb content may be 0%, but in order to obtain these effects, the Nb content is preferably 0.003% or more. For example, the Nb content may be 0.005% or more or 0.010% or more. In particular, the Nb content may be 1.000% or more or 1.500% or more from the viewpoint of sufficiently strengthening precipitation. On the other hand, if Nb is excessively contained, the effect may be saturated and the processability and / or toughness may be lowered. Therefore, the Nb content is 3.000% or less. The Nb content may be 2.800% or less, 2.500% or less, or 2.000% or less. In particular, from the viewpoint of suppressing the decrease in toughness of the weld heat affected zone (HAZ), the Nb content is preferably 0.100% or less, 0.080% or less, 0.050% or less, or 0.030. It may be less than or equal to%.
[Ti:0~0.500%]
チタン(Ti)は、析出強化等により鋼材の強度向上に寄与する元素である。Ti含有量は0%であってもよいが、このような効果を得るためには、Ti含有量は0.005%以上であることが好ましい。Ti含有量は0.010%以上、0.050%以上又は0.080%以上であってもよい。一方で、Tiを過度に含有すると、多量の析出物が生成して靭性を低下させる場合がある。したがって、Ti含有量は0.500%以下である。Ti含有量は0.300%以下、0.200%以下又は0.100%以下であってもよい。 [Ti: 0 to 0.500%]
Titanium (Ti) is an element that contributes to improving the strength of steel materials by strengthening precipitation. The Ti content may be 0%, but in order to obtain such an effect, the Ti content is preferably 0.005% or more. The Ti content may be 0.010% or more, 0.050% or more, or 0.080% or more. On the other hand, if Ti is excessively contained, a large amount of precipitates may be formed and the toughness may be lowered. Therefore, the Ti content is 0.500% or less. The Ti content may be 0.300% or less, 0.200% or less, or 0.100% or less.
チタン(Ti)は、析出強化等により鋼材の強度向上に寄与する元素である。Ti含有量は0%であってもよいが、このような効果を得るためには、Ti含有量は0.005%以上であることが好ましい。Ti含有量は0.010%以上、0.050%以上又は0.080%以上であってもよい。一方で、Tiを過度に含有すると、多量の析出物が生成して靭性を低下させる場合がある。したがって、Ti含有量は0.500%以下である。Ti含有量は0.300%以下、0.200%以下又は0.100%以下であってもよい。 [Ti: 0 to 0.500%]
Titanium (Ti) is an element that contributes to improving the strength of steel materials by strengthening precipitation. The Ti content may be 0%, but in order to obtain such an effect, the Ti content is preferably 0.005% or more. The Ti content may be 0.010% or more, 0.050% or more, or 0.080% or more. On the other hand, if Ti is excessively contained, a large amount of precipitates may be formed and the toughness may be lowered. Therefore, the Ti content is 0.500% or less. The Ti content may be 0.300% or less, 0.200% or less, or 0.100% or less.
[Ta:0~0.500%]
タンタル(Ta)は、炭化物の形態制御と強度の増加に有効な元素である。Ta含有量は0%であってもよいが、これらの効果を得るためには、Ta含有量は0.001%以上であることが好ましい。Ta含有量は0.005%以上、0.010%以上又は0.050%以上であってもよい。一方で、Taを過度に含有すると、微細なTa炭化物が多数析出し、鋼材の過度な強度上昇を招き、結果として延性の低下及び冷間加工性を低下させる場合がある。したがって、Ta含有量は0.500%以下である。Ta含有量は、0.300%以下、0.100%以下又は0.080%以下であってもよい。 [Ta: 0 to 0.500%]
Tantalum (Ta) is an element effective in controlling the morphology of carbides and increasing their strength. The Ta content may be 0%, but in order to obtain these effects, the Ta content is preferably 0.001% or more. The Ta content may be 0.005% or more, 0.010% or more, or 0.050% or more. On the other hand, if Ta is excessively contained, a large amount of fine Ta carbides may be deposited, which may lead to an excessive increase in strength of the steel material, resulting in a decrease in ductility and a decrease in cold workability. Therefore, the Ta content is 0.500% or less. The Ta content may be 0.300% or less, 0.100% or less, or 0.080% or less.
タンタル(Ta)は、炭化物の形態制御と強度の増加に有効な元素である。Ta含有量は0%であってもよいが、これらの効果を得るためには、Ta含有量は0.001%以上であることが好ましい。Ta含有量は0.005%以上、0.010%以上又は0.050%以上であってもよい。一方で、Taを過度に含有すると、微細なTa炭化物が多数析出し、鋼材の過度な強度上昇を招き、結果として延性の低下及び冷間加工性を低下させる場合がある。したがって、Ta含有量は0.500%以下である。Ta含有量は、0.300%以下、0.100%以下又は0.080%以下であってもよい。 [Ta: 0 to 0.500%]
Tantalum (Ta) is an element effective in controlling the morphology of carbides and increasing their strength. The Ta content may be 0%, but in order to obtain these effects, the Ta content is preferably 0.001% or more. The Ta content may be 0.005% or more, 0.010% or more, or 0.050% or more. On the other hand, if Ta is excessively contained, a large amount of fine Ta carbides may be deposited, which may lead to an excessive increase in strength of the steel material, resulting in a decrease in ductility and a decrease in cold workability. Therefore, the Ta content is 0.500% or less. The Ta content may be 0.300% or less, 0.100% or less, or 0.080% or less.
[V:0~1.00%]
バナジウム(V)は、析出強化等により鋼材の強度向上に寄与する元素である。V含有量は0%であってもよいが、このような効果を得るためには、V含有量は0.001%以上であることが好ましい。V含有量は0.01%以上、0.02%以上、0.05%以上又は0.10%以上であってもよい。一方で、Vを過度に含有すると、多量の析出物が生成して靭性を低下させる場合がある。したがって、V含有量は1.00%以下である。V含有量は0.80%以下、0.60%以下又は0.50%以下であってもよい。 [V: 0 to 1.00%]
Vanadium (V) is an element that contributes to improving the strength of steel materials by strengthening precipitation. The V content may be 0%, but in order to obtain such an effect, the V content is preferably 0.001% or more. The V content may be 0.01% or more, 0.02% or more, 0.05% or more, or 0.10% or more. On the other hand, if V is excessively contained, a large amount of precipitates may be formed and the toughness may be lowered. Therefore, the V content is 1.00% or less. The V content may be 0.80% or less, 0.60% or less, or 0.50% or less.
バナジウム(V)は、析出強化等により鋼材の強度向上に寄与する元素である。V含有量は0%であってもよいが、このような効果を得るためには、V含有量は0.001%以上であることが好ましい。V含有量は0.01%以上、0.02%以上、0.05%以上又は0.10%以上であってもよい。一方で、Vを過度に含有すると、多量の析出物が生成して靭性を低下させる場合がある。したがって、V含有量は1.00%以下である。V含有量は0.80%以下、0.60%以下又は0.50%以下であってもよい。 [V: 0 to 1.00%]
Vanadium (V) is an element that contributes to improving the strength of steel materials by strengthening precipitation. The V content may be 0%, but in order to obtain such an effect, the V content is preferably 0.001% or more. The V content may be 0.01% or more, 0.02% or more, 0.05% or more, or 0.10% or more. On the other hand, if V is excessively contained, a large amount of precipitates may be formed and the toughness may be lowered. Therefore, the V content is 1.00% or less. The V content may be 0.80% or less, 0.60% or less, or 0.50% or less.
[Cu:0~3.00%]
銅(Cu)は強度及び/又は耐食性の向上に寄与する元素である。Cu含有量は0%であってもよいが、これらの効果を得るためには、Cu含有量は0.001%以上であることが好ましい。Cu含有量は0.01%以上、0.10%以上、0.15%以上、0.20%以上又は0.30%以上であってもよい。一方で、Cuを過度に含有すると、靭性や溶接性の劣化を招く場合がある。したがって、Cu含有量は3.00%以下である。Cu含有量は2.00%以下、1.50%以下、1.00%以下又は0.50%以下であってもよい。 [Cu: 0 to 3.00%]
Copper (Cu) is an element that contributes to the improvement of strength and / or corrosion resistance. The Cu content may be 0%, but in order to obtain these effects, the Cu content is preferably 0.001% or more. The Cu content may be 0.01% or more, 0.10% or more, 0.15% or more, 0.20% or more, or 0.30% or more. On the other hand, if Cu is excessively contained, the toughness and weldability may be deteriorated. Therefore, the Cu content is 3.00% or less. The Cu content may be 2.00% or less, 1.50% or less, 1.00% or less, or 0.50% or less.
銅(Cu)は強度及び/又は耐食性の向上に寄与する元素である。Cu含有量は0%であってもよいが、これらの効果を得るためには、Cu含有量は0.001%以上であることが好ましい。Cu含有量は0.01%以上、0.10%以上、0.15%以上、0.20%以上又は0.30%以上であってもよい。一方で、Cuを過度に含有すると、靭性や溶接性の劣化を招く場合がある。したがって、Cu含有量は3.00%以下である。Cu含有量は2.00%以下、1.50%以下、1.00%以下又は0.50%以下であってもよい。 [Cu: 0 to 3.00%]
Copper (Cu) is an element that contributes to the improvement of strength and / or corrosion resistance. The Cu content may be 0%, but in order to obtain these effects, the Cu content is preferably 0.001% or more. The Cu content may be 0.01% or more, 0.10% or more, 0.15% or more, 0.20% or more, or 0.30% or more. On the other hand, if Cu is excessively contained, the toughness and weldability may be deteriorated. Therefore, the Cu content is 3.00% or less. The Cu content may be 2.00% or less, 1.50% or less, 1.00% or less, or 0.50% or less.
[Ni:0~60.00%]
ニッケル(Ni)は強度及び/又は耐熱性の向上に寄与する元素であり、有効なオーステナイト安定化元素でもある。Ni含有量は0%であってもよいが、これらの効果を得るためには、Ni含有量は0.001%以上であることが好ましい。Ni含有量は0.01%以上、0.10%以上、0.50%以上、0.70%以上、1.00%以上又は3.00%以上であってもよい。とりわけ、耐熱性を十分に向上させる観点からは、Ni含有量は30.00%以上、35.00%以上又は40.00%以上であってもよい。一方で、Niを過度に含有すると、合金コストの増加に加えて熱間加工時の変形抵抗が増大し、設備負荷が大きくなる場合がある。したがって、Ni含有量は60.00%以下である。Ni含有量は55.00%以下又は50.00%以下であってもよい。とりわけ、経済性の観点及び/又は溶接性の低下を抑制するという観点からは、Ni含有量は15.00%以下、10.00%以下、6.00%以下又は4.00%以下であってもよい。 [Ni: 0-60.00%]
Nickel (Ni) is an element that contributes to the improvement of strength and / or heat resistance, and is also an effective austenite stabilizing element. The Ni content may be 0%, but in order to obtain these effects, the Ni content is preferably 0.001% or more. The Ni content may be 0.01% or more, 0.10% or more, 0.50% or more, 0.70% or more, 1.00% or more, or 3.00% or more. In particular, from the viewpoint of sufficiently improving the heat resistance, the Ni content may be 30.00% or more, 35.00% or more, or 40.00% or more. On the other hand, if Ni is excessively contained, the deformation resistance during hot working increases in addition to the increase in alloy cost, which may increase the equipment load. Therefore, the Ni content is 60.00% or less. The Ni content may be 55.00% or less or 50.00% or less. In particular, from the viewpoint of economic efficiency and / or from the viewpoint of suppressing deterioration of weldability, the Ni content is 15.00% or less, 10.00% or less, 6.00% or less, or 4.00% or less. You may.
ニッケル(Ni)は強度及び/又は耐熱性の向上に寄与する元素であり、有効なオーステナイト安定化元素でもある。Ni含有量は0%であってもよいが、これらの効果を得るためには、Ni含有量は0.001%以上であることが好ましい。Ni含有量は0.01%以上、0.10%以上、0.50%以上、0.70%以上、1.00%以上又は3.00%以上であってもよい。とりわけ、耐熱性を十分に向上させる観点からは、Ni含有量は30.00%以上、35.00%以上又は40.00%以上であってもよい。一方で、Niを過度に含有すると、合金コストの増加に加えて熱間加工時の変形抵抗が増大し、設備負荷が大きくなる場合がある。したがって、Ni含有量は60.00%以下である。Ni含有量は55.00%以下又は50.00%以下であってもよい。とりわけ、経済性の観点及び/又は溶接性の低下を抑制するという観点からは、Ni含有量は15.00%以下、10.00%以下、6.00%以下又は4.00%以下であってもよい。 [Ni: 0-60.00%]
Nickel (Ni) is an element that contributes to the improvement of strength and / or heat resistance, and is also an effective austenite stabilizing element. The Ni content may be 0%, but in order to obtain these effects, the Ni content is preferably 0.001% or more. The Ni content may be 0.01% or more, 0.10% or more, 0.50% or more, 0.70% or more, 1.00% or more, or 3.00% or more. In particular, from the viewpoint of sufficiently improving the heat resistance, the Ni content may be 30.00% or more, 35.00% or more, or 40.00% or more. On the other hand, if Ni is excessively contained, the deformation resistance during hot working increases in addition to the increase in alloy cost, which may increase the equipment load. Therefore, the Ni content is 60.00% or less. The Ni content may be 55.00% or less or 50.00% or less. In particular, from the viewpoint of economic efficiency and / or from the viewpoint of suppressing deterioration of weldability, the Ni content is 15.00% or less, 10.00% or less, 6.00% or less, or 4.00% or less. You may.
[Cr:0~30.00%]
クロム(Cr)は強度及び/又は耐食性の向上に寄与する元素である。Cr含有量は0%であってもよいが、これらの効果を得るためには、Cr含有量は0.001%以上であることが好ましい。Cr含有量は0.01%以上、0.05%以上、0.10%以上又は0.50%以上であってもよい。とりわけ、耐食性を十分に向上させる観点からは、Cr含有量は10.00%以上、12.00%以上又は15.00%以上であってもよい。一方で、Crを過度に含有すると、合金コストの増加に加えて靭性が低下する場合がある。したがって、Cr含有量は30.00%以下である。Cr含有量は28.00%以下、25.00%以下又は20.00%以下であってもよい。とりわけ、溶接性及び/又は加工性の低下を抑制するという観点からは、Cr含有量は10.00%以下、9.00%以下又は7.50%以下であってもよい。 [Cr: 0 to 30.00%]
Chromium (Cr) is an element that contributes to the improvement of strength and / or corrosion resistance. The Cr content may be 0%, but in order to obtain these effects, the Cr content is preferably 0.001% or more. The Cr content may be 0.01% or more, 0.05% or more, 0.10% or more, or 0.50% or more. In particular, from the viewpoint of sufficiently improving the corrosion resistance, the Cr content may be 10.00% or more, 12.00% or more, or 15.00% or more. On the other hand, if Cr is excessively contained, the toughness may decrease in addition to the increase in alloy cost. Therefore, the Cr content is 30.00% or less. The Cr content may be 28.00% or less, 25.00% or less, or 20.00% or less. In particular, from the viewpoint of suppressing deterioration of weldability and / or processability, the Cr content may be 10.00% or less, 9.00% or less, or 7.50% or less.
クロム(Cr)は強度及び/又は耐食性の向上に寄与する元素である。Cr含有量は0%であってもよいが、これらの効果を得るためには、Cr含有量は0.001%以上であることが好ましい。Cr含有量は0.01%以上、0.05%以上、0.10%以上又は0.50%以上であってもよい。とりわけ、耐食性を十分に向上させる観点からは、Cr含有量は10.00%以上、12.00%以上又は15.00%以上であってもよい。一方で、Crを過度に含有すると、合金コストの増加に加えて靭性が低下する場合がある。したがって、Cr含有量は30.00%以下である。Cr含有量は28.00%以下、25.00%以下又は20.00%以下であってもよい。とりわけ、溶接性及び/又は加工性の低下を抑制するという観点からは、Cr含有量は10.00%以下、9.00%以下又は7.50%以下であってもよい。 [Cr: 0 to 30.00%]
Chromium (Cr) is an element that contributes to the improvement of strength and / or corrosion resistance. The Cr content may be 0%, but in order to obtain these effects, the Cr content is preferably 0.001% or more. The Cr content may be 0.01% or more, 0.05% or more, 0.10% or more, or 0.50% or more. In particular, from the viewpoint of sufficiently improving the corrosion resistance, the Cr content may be 10.00% or more, 12.00% or more, or 15.00% or more. On the other hand, if Cr is excessively contained, the toughness may decrease in addition to the increase in alloy cost. Therefore, the Cr content is 30.00% or less. The Cr content may be 28.00% or less, 25.00% or less, or 20.00% or less. In particular, from the viewpoint of suppressing deterioration of weldability and / or processability, the Cr content may be 10.00% or less, 9.00% or less, or 7.50% or less.
[Mo:0~5.00%]
モリブデン(Mo)は鋼の焼入れ性を高め、強度の向上に寄与する元素であり、耐食性の向上にも寄与する元素である。Mo含有量は0%であってもよいが、これらの効果を得るためには、Mo含有量は0.001%以上であることが好ましい。Mo含有量は0.01%以上、0.02%以上、0.50%以上又は1.00%以上であってもよい。一方で、Moを過度に含有すると、熱間加工時の変形抵抗が増大し、設備負荷が大きくなる場合がある。したがって、Mo含有量は5.00%以下である。Mo含有量は4.50%以下、4.00%以下、3.00以下又は1.50%以下であってもよい。 [Mo: 0 to 5.00%]
Molybdenum (Mo) is an element that enhances the hardenability of steel and contributes to the improvement of strength, and is also an element that contributes to the improvement of corrosion resistance. The Mo content may be 0%, but in order to obtain these effects, the Mo content is preferably 0.001% or more. The Mo content may be 0.01% or more, 0.02% or more, 0.50% or more, or 1.00% or more. On the other hand, if Mo is excessively contained, the deformation resistance during hot working increases, and the equipment load may increase. Therefore, the Mo content is 5.00% or less. The Mo content may be 4.50% or less, 4.00% or less, 3.00 or less, or 1.50% or less.
モリブデン(Mo)は鋼の焼入れ性を高め、強度の向上に寄与する元素であり、耐食性の向上にも寄与する元素である。Mo含有量は0%であってもよいが、これらの効果を得るためには、Mo含有量は0.001%以上であることが好ましい。Mo含有量は0.01%以上、0.02%以上、0.50%以上又は1.00%以上であってもよい。一方で、Moを過度に含有すると、熱間加工時の変形抵抗が増大し、設備負荷が大きくなる場合がある。したがって、Mo含有量は5.00%以下である。Mo含有量は4.50%以下、4.00%以下、3.00以下又は1.50%以下であってもよい。 [Mo: 0 to 5.00%]
Molybdenum (Mo) is an element that enhances the hardenability of steel and contributes to the improvement of strength, and is also an element that contributes to the improvement of corrosion resistance. The Mo content may be 0%, but in order to obtain these effects, the Mo content is preferably 0.001% or more. The Mo content may be 0.01% or more, 0.02% or more, 0.50% or more, or 1.00% or more. On the other hand, if Mo is excessively contained, the deformation resistance during hot working increases, and the equipment load may increase. Therefore, the Mo content is 5.00% or less. The Mo content may be 4.50% or less, 4.00% or less, 3.00 or less, or 1.50% or less.
[W:0~2.00%]
タングステン(W)は鋼の焼入れ性を高め、強度の向上に寄与する元素である。W含有量は0%であってもよいが、このような効果を得るためには、W含有量は0.001%以上であることが好ましい。W含有量は0.01%以上、0.02%以上、0.05%以上、0.10%以上又は0.50%以上であってもよい。一方で、Wを過度に含有すると、延性や溶接性が低下する場合がある。したがって、W含有量は2.00%以下である。W含有量は1.80%以下、1.50%以下又は1.00%以下であってもよい。 [W: 0 to 2.00%]
Tungsten (W) is an element that enhances the hardenability of steel and contributes to the improvement of strength. The W content may be 0%, but in order to obtain such an effect, the W content is preferably 0.001% or more. The W content may be 0.01% or more, 0.02% or more, 0.05% or more, 0.10% or more, or 0.50% or more. On the other hand, if W is excessively contained, ductility and weldability may decrease. Therefore, the W content is 2.00% or less. The W content may be 1.80% or less, 1.50% or less, or 1.00% or less.
タングステン(W)は鋼の焼入れ性を高め、強度の向上に寄与する元素である。W含有量は0%であってもよいが、このような効果を得るためには、W含有量は0.001%以上であることが好ましい。W含有量は0.01%以上、0.02%以上、0.05%以上、0.10%以上又は0.50%以上であってもよい。一方で、Wを過度に含有すると、延性や溶接性が低下する場合がある。したがって、W含有量は2.00%以下である。W含有量は1.80%以下、1.50%以下又は1.00%以下であってもよい。 [W: 0 to 2.00%]
Tungsten (W) is an element that enhances the hardenability of steel and contributes to the improvement of strength. The W content may be 0%, but in order to obtain such an effect, the W content is preferably 0.001% or more. The W content may be 0.01% or more, 0.02% or more, 0.05% or more, 0.10% or more, or 0.50% or more. On the other hand, if W is excessively contained, ductility and weldability may decrease. Therefore, the W content is 2.00% or less. The W content may be 1.80% or less, 1.50% or less, or 1.00% or less.
[B:0~0.0200%]
ホウ素(B)は強度の向上に寄与する元素である。B含有量は0%であってもよいが、このような効果を得るためには、B含有量は0.0001%以上であることが好ましい。B含有量は0.0003%以上、0.0005%以上又は0.0007%以上であってもよい。一方で、Bを過度に含有すると、靭性及び/又は溶接性が低下する場合がある。したがって、B含有量は0.0200%以下である。B含有量は0.0100%以下、0.0050%以下、0.0030%以下又は0.0020%以下であってもよい。 [B: 0 to 0.0200%]
Boron (B) is an element that contributes to the improvement of strength. The B content may be 0%, but in order to obtain such an effect, the B content is preferably 0.0001% or more. The B content may be 0.0003% or more, 0.0005% or more, or 0.0007% or more. On the other hand, if B is excessively contained, toughness and / or weldability may decrease. Therefore, the B content is 0.0200% or less. The B content may be 0.0100% or less, 0.0050% or less, 0.0030% or less, or 0.0020% or less.
ホウ素(B)は強度の向上に寄与する元素である。B含有量は0%であってもよいが、このような効果を得るためには、B含有量は0.0001%以上であることが好ましい。B含有量は0.0003%以上、0.0005%以上又は0.0007%以上であってもよい。一方で、Bを過度に含有すると、靭性及び/又は溶接性が低下する場合がある。したがって、B含有量は0.0200%以下である。B含有量は0.0100%以下、0.0050%以下、0.0030%以下又は0.0020%以下であってもよい。 [B: 0 to 0.0200%]
Boron (B) is an element that contributes to the improvement of strength. The B content may be 0%, but in order to obtain such an effect, the B content is preferably 0.0001% or more. The B content may be 0.0003% or more, 0.0005% or more, or 0.0007% or more. On the other hand, if B is excessively contained, toughness and / or weldability may decrease. Therefore, the B content is 0.0200% or less. The B content may be 0.0100% or less, 0.0050% or less, 0.0030% or less, or 0.0020% or less.
[Co:0~3.00%]
コバルト(Co)は焼入れ性及び/又は耐熱性の向上に寄与する元素である。Co含有量は0%であってもよいが、これらの効果を得るためには、Co含有量は0.001%以上であることが好ましい。Co含有量は0.01%以上、0.02%以上、0.05%以上、0.10%以上又は0.50%以上であってもよい。一方で、Coを過度に含有すると、熱間加工性が低下する場合があり、原料コストの増加にも繋がる。したがって、Co含有量は3.00%以下である。Co含有量は2.50%以下、2.00%以下、1.50%以下又は0.80%以下であってもよい。 [Co: 0 to 3.00%]
Cobalt (Co) is an element that contributes to the improvement of hardenability and / or heat resistance. The Co content may be 0%, but in order to obtain these effects, the Co content is preferably 0.001% or more. The Co content may be 0.01% or more, 0.02% or more, 0.05% or more, 0.10% or more, or 0.50% or more. On the other hand, if Co is excessively contained, the hot workability may be lowered, which leads to an increase in raw material cost. Therefore, the Co content is 3.00% or less. The Co content may be 2.50% or less, 2.00% or less, 1.50% or less, or 0.80% or less.
コバルト(Co)は焼入れ性及び/又は耐熱性の向上に寄与する元素である。Co含有量は0%であってもよいが、これらの効果を得るためには、Co含有量は0.001%以上であることが好ましい。Co含有量は0.01%以上、0.02%以上、0.05%以上、0.10%以上又は0.50%以上であってもよい。一方で、Coを過度に含有すると、熱間加工性が低下する場合があり、原料コストの増加にも繋がる。したがって、Co含有量は3.00%以下である。Co含有量は2.50%以下、2.00%以下、1.50%以下又は0.80%以下であってもよい。 [Co: 0 to 3.00%]
Cobalt (Co) is an element that contributes to the improvement of hardenability and / or heat resistance. The Co content may be 0%, but in order to obtain these effects, the Co content is preferably 0.001% or more. The Co content may be 0.01% or more, 0.02% or more, 0.05% or more, 0.10% or more, or 0.50% or more. On the other hand, if Co is excessively contained, the hot workability may be lowered, which leads to an increase in raw material cost. Therefore, the Co content is 3.00% or less. The Co content may be 2.50% or less, 2.00% or less, 1.50% or less, or 0.80% or less.
[Be:0~0.050%]
ベリリウム(Be)は、母材の強度の上昇及び組織の微細化に有効な元素である。Be含有量は0%であってもよいが、このような効果を得るためには、Be含有量は0.0003%以上であることが好ましい。Be含有量は0.0005%以上、0.001%以上又は0.010%以上であってもよい。一方で、Beを過度に含有すると、成形性が低下する場合がある。したがって、Be含有量は0.050%以下である。Be含有量は0.040%以下、0.030%以下又は0.020%以下であってもよい。 [Be: 0 to 0.050%]
Beryllium (Be) is an element effective for increasing the strength of the base metal and refining the structure. The Be content may be 0%, but in order to obtain such an effect, the Be content is preferably 0.0003% or more. The Be content may be 0.0005% or more, 0.001% or more, or 0.010% or more. On the other hand, if Be is excessively contained, the moldability may be deteriorated. Therefore, the Be content is 0.050% or less. The Be content may be 0.040% or less, 0.030% or less, or 0.020% or less.
ベリリウム(Be)は、母材の強度の上昇及び組織の微細化に有効な元素である。Be含有量は0%であってもよいが、このような効果を得るためには、Be含有量は0.0003%以上であることが好ましい。Be含有量は0.0005%以上、0.001%以上又は0.010%以上であってもよい。一方で、Beを過度に含有すると、成形性が低下する場合がある。したがって、Be含有量は0.050%以下である。Be含有量は0.040%以下、0.030%以下又は0.020%以下であってもよい。 [Be: 0 to 0.050%]
Beryllium (Be) is an element effective for increasing the strength of the base metal and refining the structure. The Be content may be 0%, but in order to obtain such an effect, the Be content is preferably 0.0003% or more. The Be content may be 0.0005% or more, 0.001% or more, or 0.010% or more. On the other hand, if Be is excessively contained, the moldability may be deteriorated. Therefore, the Be content is 0.050% or less. The Be content may be 0.040% or less, 0.030% or less, or 0.020% or less.
[Ag:0~0.500%]
銀(Ag)は、母材の強度の上昇及び組織の微細化に有効な元素である。Ag含有量は0%であってもよいが、このような効果を得るためには、Ag含有量は0.001%以上であることが好ましい。Ag含有量は0.010%以上、0.020%以上、0.030%以上又は0.050%以上であってもよい。一方で、Agを過度に含有すると、成形性が低下する場合がある。したがって、Ag含有量は0.500%以下である。Ag含有量は0.400%以下、0.300%以下又は0.200%以下であってもよい。 [Ag: 0 to 0.500%]
Silver (Ag) is an element effective for increasing the strength of the base material and refining the structure. The Ag content may be 0%, but in order to obtain such an effect, the Ag content is preferably 0.001% or more. The Ag content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.050% or more. On the other hand, if Ag is excessively contained, the moldability may be deteriorated. Therefore, the Ag content is 0.500% or less. The Ag content may be 0.400% or less, 0.300% or less, or 0.200% or less.
銀(Ag)は、母材の強度の上昇及び組織の微細化に有効な元素である。Ag含有量は0%であってもよいが、このような効果を得るためには、Ag含有量は0.001%以上であることが好ましい。Ag含有量は0.010%以上、0.020%以上、0.030%以上又は0.050%以上であってもよい。一方で、Agを過度に含有すると、成形性が低下する場合がある。したがって、Ag含有量は0.500%以下である。Ag含有量は0.400%以下、0.300%以下又は0.200%以下であってもよい。 [Ag: 0 to 0.500%]
Silver (Ag) is an element effective for increasing the strength of the base material and refining the structure. The Ag content may be 0%, but in order to obtain such an effect, the Ag content is preferably 0.001% or more. The Ag content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.050% or more. On the other hand, if Ag is excessively contained, the moldability may be deteriorated. Therefore, the Ag content is 0.500% or less. The Ag content may be 0.400% or less, 0.300% or less, or 0.200% or less.
[Ca:0~0.0500%]
カルシウム(Ca)は、硫化物の形態を制御できる元素である。Ca含有量は0%であってもよいが、このような効果を得るためには、Ca含有量は0.0001%以上であることが好ましい。一方で、Caを過度に含有しても効果が飽和し、それゆえCaを必要以上に鋼材中に含有させることは製造コストの上昇を招く虞がある。したがって、Ca含有量は0.0500%以下である。 [Ca: 0-0.0500%]
Calcium (Ca) is an element that can control the morphology of sulfides. The Ca content may be 0%, but in order to obtain such an effect, the Ca content is preferably 0.0001% or more. On the other hand, even if Ca is excessively contained, the effect is saturated, and therefore, if Ca is contained in the steel material more than necessary, the manufacturing cost may increase. Therefore, the Ca content is 0.0500% or less.
カルシウム(Ca)は、硫化物の形態を制御できる元素である。Ca含有量は0%であってもよいが、このような効果を得るためには、Ca含有量は0.0001%以上であることが好ましい。一方で、Caを過度に含有しても効果が飽和し、それゆえCaを必要以上に鋼材中に含有させることは製造コストの上昇を招く虞がある。したがって、Ca含有量は0.0500%以下である。 [Ca: 0-0.0500%]
Calcium (Ca) is an element that can control the morphology of sulfides. The Ca content may be 0%, but in order to obtain such an effect, the Ca content is preferably 0.0001% or more. On the other hand, even if Ca is excessively contained, the effect is saturated, and therefore, if Ca is contained in the steel material more than necessary, the manufacturing cost may increase. Therefore, the Ca content is 0.0500% or less.
[Mg:0~0.0500%]
マグネシウム(Mg)は、硫化物の形態を制御できる元素である。Mg含有量は0%であってもよいが、このような効果を得るためには、Mg含有量は0.0001%以上であることが好ましい。Mg含有量は0.0015%超、0.0016%以上、0.0018%以上又は0.0020%以上であってもよい。一方で、Mgを過度に含有しても効果が飽和し、粗大な介在物の形成に起因して冷間成形性及び/又は靭性が低下する場合がある。したがって、Mg含有量は0.0500%以下である。Mg含有量は0.0400%以下、0.0300%以下又は0.0200%以下であってもよい。 [Mg: 0 to 0.0500%]
Magnesium (Mg) is an element that can control the morphology of sulfides. The Mg content may be 0%, but in order to obtain such an effect, the Mg content is preferably 0.0001% or more. The Mg content may be greater than 0.0015%, greater than 0.0016%, greater than or equal to 0.0018% or greater than or equal to 0.0020%. On the other hand, even if Mg is excessively contained, the effect is saturated, and cold formability and / or toughness may decrease due to the formation of coarse inclusions. Therefore, the Mg content is 0.0500% or less. The Mg content may be 0.0400% or less, 0.0300% or less, or 0.0200% or less.
マグネシウム(Mg)は、硫化物の形態を制御できる元素である。Mg含有量は0%であってもよいが、このような効果を得るためには、Mg含有量は0.0001%以上であることが好ましい。Mg含有量は0.0015%超、0.0016%以上、0.0018%以上又は0.0020%以上であってもよい。一方で、Mgを過度に含有しても効果が飽和し、粗大な介在物の形成に起因して冷間成形性及び/又は靭性が低下する場合がある。したがって、Mg含有量は0.0500%以下である。Mg含有量は0.0400%以下、0.0300%以下又は0.0200%以下であってもよい。 [Mg: 0 to 0.0500%]
Magnesium (Mg) is an element that can control the morphology of sulfides. The Mg content may be 0%, but in order to obtain such an effect, the Mg content is preferably 0.0001% or more. The Mg content may be greater than 0.0015%, greater than 0.0016%, greater than or equal to 0.0018% or greater than or equal to 0.0020%. On the other hand, even if Mg is excessively contained, the effect is saturated, and cold formability and / or toughness may decrease due to the formation of coarse inclusions. Therefore, the Mg content is 0.0500% or less. The Mg content may be 0.0400% or less, 0.0300% or less, or 0.0200% or less.
[La、Ce、Nd、Y、Pm、Pr、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、及びScの少なくとも1種:合計で0~0.5000%]
ランタン(La)、セリウム(Ce)、ネオジム(Nd)、イットリウム(Y)、プロメチウム(Pm)、プラセオジム(Pr)、サマリウム(Sm)、ユウロピウム(Eu)、ガドリニウム(Gd)、テルビウム(Tb)、ジスプロシウム(Dy)、ホルミウム(Ho)、エルビウム(Er)、ツリウム(Tm)、イッテルビウム(Yb)、ルテチウム(Lu)、及びスカンジウム(Sc)は、Ca及びMgと同様に硫化物の形態を制御できる元素である。La、Ce、Nd、Y、Pm、Pr、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、及びScの少なくとも1種の含有量の合計は0%であってもよいが、このような効果を得るためには0.0001%以上であることが好ましい。La、Ce、Nd、Y、Pm、Pr、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、及びScの少なくとも1種の含有量の合計は0.0002%以上、0.0003%以上又は0.0004%以上であってもよい。一方で、これらの元素を過度に含有しても効果が飽和し、それゆえこれらの元素を必要以上に鋼材中に含有させることは製造コストの上昇を招く虞がある。したがって、La、Ce、Nd、Y、Pm、Pr、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、及びScの少なくとも1種の含有量の合計は0.5000%以下であり、0.4000%以下、0.3000%以下又は0.2000%以下であってもよい。 [At least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc: 0 to 0.5000% in total]
Lantern (La), Cerium (Ce), Neogym (Nd), Yttrium (Y), Promethium (Pm), Placeozim (Pr), Samarium (Sm), Europium (Eu), Gadrinium (Gd), Terbium (Tb), Dysprosium (Dy), formium (Ho), elbium (Er), yttrium (Tm), yttrium (Yb), lutetium (Lu), and scandium (Sc) can control the morphology of sulfides as well as Ca and Mg. It is an element. Even if the total content of at least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc is 0%. However, in order to obtain such an effect, it is preferably 0.0001% or more. The total content of at least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc is 0.0002% or more. It may be 0.0003% or more or 0.0004% or more. On the other hand, even if these elements are excessively contained, the effect is saturated, and therefore, including these elements in the steel material more than necessary may lead to an increase in manufacturing cost. Therefore, the total content of at least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc is 0.5000%. It may be less than or equal to 0.4000%, 0.3000% or less, or 0.2000% or less.
ランタン(La)、セリウム(Ce)、ネオジム(Nd)、イットリウム(Y)、プロメチウム(Pm)、プラセオジム(Pr)、サマリウム(Sm)、ユウロピウム(Eu)、ガドリニウム(Gd)、テルビウム(Tb)、ジスプロシウム(Dy)、ホルミウム(Ho)、エルビウム(Er)、ツリウム(Tm)、イッテルビウム(Yb)、ルテチウム(Lu)、及びスカンジウム(Sc)は、Ca及びMgと同様に硫化物の形態を制御できる元素である。La、Ce、Nd、Y、Pm、Pr、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、及びScの少なくとも1種の含有量の合計は0%であってもよいが、このような効果を得るためには0.0001%以上であることが好ましい。La、Ce、Nd、Y、Pm、Pr、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、及びScの少なくとも1種の含有量の合計は0.0002%以上、0.0003%以上又は0.0004%以上であってもよい。一方で、これらの元素を過度に含有しても効果が飽和し、それゆえこれらの元素を必要以上に鋼材中に含有させることは製造コストの上昇を招く虞がある。したがって、La、Ce、Nd、Y、Pm、Pr、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、及びScの少なくとも1種の含有量の合計は0.5000%以下であり、0.4000%以下、0.3000%以下又は0.2000%以下であってもよい。 [At least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc: 0 to 0.5000% in total]
Lantern (La), Cerium (Ce), Neogym (Nd), Yttrium (Y), Promethium (Pm), Placeozim (Pr), Samarium (Sm), Europium (Eu), Gadrinium (Gd), Terbium (Tb), Dysprosium (Dy), formium (Ho), elbium (Er), yttrium (Tm), yttrium (Yb), lutetium (Lu), and scandium (Sc) can control the morphology of sulfides as well as Ca and Mg. It is an element. Even if the total content of at least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc is 0%. However, in order to obtain such an effect, it is preferably 0.0001% or more. The total content of at least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc is 0.0002% or more. It may be 0.0003% or more or 0.0004% or more. On the other hand, even if these elements are excessively contained, the effect is saturated, and therefore, including these elements in the steel material more than necessary may lead to an increase in manufacturing cost. Therefore, the total content of at least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc is 0.5000%. It may be less than or equal to 0.4000%, 0.3000% or less, or 0.2000% or less.
[Sn:0~0.300%]
錫(Sn)は耐食性の向上に有効な元素である。Sn含有量は0%であってもよいが、このような効果を得るためには、Sn含有量は0.001%以上であることが好ましい。Sn含有量は0.010%以上、0.020%以上、0.030%以上又は0.050%以上であってもよい。一方で、Snを過度に含有すると、靭性、特には低温靭性の低下を招く場合がある。したがって、Sn含有量は0.300%以下である。Sn含有量は0.250%以下、0.200%以下又は0.150%以下であってもよい。 [Sn: 0 to 0.300%]
Tin (Sn) is an element effective for improving corrosion resistance. The Sn content may be 0%, but in order to obtain such an effect, the Sn content is preferably 0.001% or more. The Sn content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.050% or more. On the other hand, excessive inclusion of Sn may lead to a decrease in toughness, particularly low temperature toughness. Therefore, the Sn content is 0.300% or less. The Sn content may be 0.250% or less, 0.200% or less, or 0.150% or less.
錫(Sn)は耐食性の向上に有効な元素である。Sn含有量は0%であってもよいが、このような効果を得るためには、Sn含有量は0.001%以上であることが好ましい。Sn含有量は0.010%以上、0.020%以上、0.030%以上又は0.050%以上であってもよい。一方で、Snを過度に含有すると、靭性、特には低温靭性の低下を招く場合がある。したがって、Sn含有量は0.300%以下である。Sn含有量は0.250%以下、0.200%以下又は0.150%以下であってもよい。 [Sn: 0 to 0.300%]
Tin (Sn) is an element effective for improving corrosion resistance. The Sn content may be 0%, but in order to obtain such an effect, the Sn content is preferably 0.001% or more. The Sn content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.050% or more. On the other hand, excessive inclusion of Sn may lead to a decrease in toughness, particularly low temperature toughness. Therefore, the Sn content is 0.300% or less. The Sn content may be 0.250% or less, 0.200% or less, or 0.150% or less.
[Sb:0~0.300%]
アンチモン(Sb)は、Snと同様に耐食性の向上に有効な元素であり、特にSnと複合して含有させることにより効果を増大させることができる。Sb含有量は0%であってもよいが、耐食性向上の効果を得るためには、Sb含有量は0.001%以上であることが好ましい。Sb含有量は0.010%以上、0.020%以上、0.030%以上又は0.050%以上であってもよい。一方で、Sbを過度に含有すると、靭性、特には低温靭性の低下を招く場合がある。したがって、Sb含有量は0.300%以下である。Sb含有量は0.250%以下、0.200%以下又は0.150%以下であってもよい。 [Sb: 0 to 0.300%]
Antimony (Sb) is an element effective for improving corrosion resistance like Sn, and the effect can be increased by including it in combination with Sn. The Sb content may be 0%, but in order to obtain the effect of improving the corrosion resistance, the Sb content is preferably 0.001% or more. The Sb content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.050% or more. On the other hand, excessive content of Sb may lead to a decrease in toughness, particularly low temperature toughness. Therefore, the Sb content is 0.300% or less. The Sb content may be 0.250% or less, 0.200% or less, or 0.150% or less.
アンチモン(Sb)は、Snと同様に耐食性の向上に有効な元素であり、特にSnと複合して含有させることにより効果を増大させることができる。Sb含有量は0%であってもよいが、耐食性向上の効果を得るためには、Sb含有量は0.001%以上であることが好ましい。Sb含有量は0.010%以上、0.020%以上、0.030%以上又は0.050%以上であってもよい。一方で、Sbを過度に含有すると、靭性、特には低温靭性の低下を招く場合がある。したがって、Sb含有量は0.300%以下である。Sb含有量は0.250%以下、0.200%以下又は0.150%以下であってもよい。 [Sb: 0 to 0.300%]
Antimony (Sb) is an element effective for improving corrosion resistance like Sn, and the effect can be increased by including it in combination with Sn. The Sb content may be 0%, but in order to obtain the effect of improving the corrosion resistance, the Sb content is preferably 0.001% or more. The Sb content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.050% or more. On the other hand, excessive content of Sb may lead to a decrease in toughness, particularly low temperature toughness. Therefore, the Sb content is 0.300% or less. The Sb content may be 0.250% or less, 0.200% or less, or 0.150% or less.
[Te:0~0.100%]
テルル(Te)は、MnやSなどと低融点化合物を形成して潤滑効果を高めるため、鋼の被削性を改善するのに有効な元素である。Te含有量は0%であってもよいが、このような効果を得るためには、Te含有量は0.001%以上であることが好ましい。Te含有量は0.010%以上、0.020%以上、0.030%以上又は0.040%以上であってもよい。一方で、Teを過度に含有しても効果が飽和し、合金コストの増加を招く。したがって、Te含有量は0.100%以下である。Te含有量は0.090%以下、0.080%以下又は0.070%以下であってもよい。 [Te: 0 to 0.100%]
Tellurium (Te) is an element effective for improving the machinability of steel because it forms a low melting point compound with Mn, S and the like to enhance the lubricating effect. The Te content may be 0%, but in order to obtain such an effect, the Te content is preferably 0.001% or more. The Te content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.040% or more. On the other hand, even if Te is excessively contained, the effect is saturated and the alloy cost increases. Therefore, the Te content is 0.100% or less. The Te content may be 0.090% or less, 0.080% or less, or 0.070% or less.
テルル(Te)は、MnやSなどと低融点化合物を形成して潤滑効果を高めるため、鋼の被削性を改善するのに有効な元素である。Te含有量は0%であってもよいが、このような効果を得るためには、Te含有量は0.001%以上であることが好ましい。Te含有量は0.010%以上、0.020%以上、0.030%以上又は0.040%以上であってもよい。一方で、Teを過度に含有しても効果が飽和し、合金コストの増加を招く。したがって、Te含有量は0.100%以下である。Te含有量は0.090%以下、0.080%以下又は0.070%以下であってもよい。 [Te: 0 to 0.100%]
Tellurium (Te) is an element effective for improving the machinability of steel because it forms a low melting point compound with Mn, S and the like to enhance the lubricating effect. The Te content may be 0%, but in order to obtain such an effect, the Te content is preferably 0.001% or more. The Te content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.040% or more. On the other hand, even if Te is excessively contained, the effect is saturated and the alloy cost increases. Therefore, the Te content is 0.100% or less. The Te content may be 0.090% or less, 0.080% or less, or 0.070% or less.
[Se:0~0.100%]
セレン(Se)は、鋼中に生成するセレン化物が被削材のせん断塑性変形に変化を与え、切りくずが破砕されやすくなるため、鋼の被削性を改善するのに有効な元素である。Se含有量は0%であってもよいが、このような効果を得るためには、Se含有量は0.001%以上であることが好ましい。Se含有量は0.010%以上、0.020%以上、0.030%以上又は0.040%以上であってもよい。一方で、Seを過度に含有しても効果が飽和し、合金コストの増加を招く。したがって、Se含有量は0.100%以下である。Se含有量は0.090%以下、0.080%以下又は0.070%以下であってもよい。 [Se: 0 to 0.100%]
Selenium (Se) is an effective element for improving the machinability of steel because the selenium produced in the steel changes the shear-plastic deformation of the work material and the chips are easily crushed. .. The Se content may be 0%, but in order to obtain such an effect, the Se content is preferably 0.001% or more. The Se content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.040% or more. On the other hand, even if Se is excessively contained, the effect is saturated and the alloy cost increases. Therefore, the Se content is 0.100% or less. The Se content may be 0.090% or less, 0.080% or less, or 0.070% or less.
セレン(Se)は、鋼中に生成するセレン化物が被削材のせん断塑性変形に変化を与え、切りくずが破砕されやすくなるため、鋼の被削性を改善するのに有効な元素である。Se含有量は0%であってもよいが、このような効果を得るためには、Se含有量は0.001%以上であることが好ましい。Se含有量は0.010%以上、0.020%以上、0.030%以上又は0.040%以上であってもよい。一方で、Seを過度に含有しても効果が飽和し、合金コストの増加を招く。したがって、Se含有量は0.100%以下である。Se含有量は0.090%以下、0.080%以下又は0.070%以下であってもよい。 [Se: 0 to 0.100%]
Selenium (Se) is an effective element for improving the machinability of steel because the selenium produced in the steel changes the shear-plastic deformation of the work material and the chips are easily crushed. .. The Se content may be 0%, but in order to obtain such an effect, the Se content is preferably 0.001% or more. The Se content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.040% or more. On the other hand, even if Se is excessively contained, the effect is saturated and the alloy cost increases. Therefore, the Se content is 0.100% or less. The Se content may be 0.090% or less, 0.080% or less, or 0.070% or less.
[As:0~0.050%]
ヒ素(As)は、鋼の被削性を改善するのに有効な元素である。As含有量は0%であってもよいが、このような効果を得るためには、As含有量は0.001%以上であることが好ましい。As含有量は0.005%以上又は0.010%以上であってもよい。一方で、Asを過度に含有すると、熱間加工性が低下する場合がある。したがって、As含有量は0.050%以下である。As含有量は0.040%以下、0.030%以下又は0.020%以下であってもよい。 [As: 0 to 0.050%]
Arsenic (As) is an element effective in improving the machinability of steel. The As content may be 0%, but in order to obtain such an effect, the As content is preferably 0.001% or more. The As content may be 0.005% or more or 0.010% or more. On the other hand, if As is excessively contained, the hot workability may be deteriorated. Therefore, the As content is 0.050% or less. The As content may be 0.040% or less, 0.030% or less, or 0.020% or less.
ヒ素(As)は、鋼の被削性を改善するのに有効な元素である。As含有量は0%であってもよいが、このような効果を得るためには、As含有量は0.001%以上であることが好ましい。As含有量は0.005%以上又は0.010%以上であってもよい。一方で、Asを過度に含有すると、熱間加工性が低下する場合がある。したがって、As含有量は0.050%以下である。As含有量は0.040%以下、0.030%以下又は0.020%以下であってもよい。 [As: 0 to 0.050%]
Arsenic (As) is an element effective in improving the machinability of steel. The As content may be 0%, but in order to obtain such an effect, the As content is preferably 0.001% or more. The As content may be 0.005% or more or 0.010% or more. On the other hand, if As is excessively contained, the hot workability may be deteriorated. Therefore, the As content is 0.050% or less. The As content may be 0.040% or less, 0.030% or less, or 0.020% or less.
[Bi:0~0.500%]
ビスマス(Bi)は、鋼の被削性を改善するのに有効な元素である。Bi含有量は0%であってもよいが、このような効果を得るためには、Bi含有量は0.001%以上であることが好ましい。Bi含有量は0.010%以上、0.020%以上、0.030%以上又は0.050%以上であってもよい。一方で、Biを過度に含有しても効果が飽和し、合金コストの増加を招く。したがって、Bi含有量は0.500%以下である。Bi含有量は0.400%以下、0.300%以下又は0.200%以下であってもよい。 [Bi: 0 to 0.500%]
Bismuth (Bi) is an element effective in improving the machinability of steel. The Bi content may be 0%, but in order to obtain such an effect, the Bi content is preferably 0.001% or more. The Bi content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.050% or more. On the other hand, even if Bi is excessively contained, the effect is saturated and the alloy cost increases. Therefore, the Bi content is 0.500% or less. The Bi content may be 0.400% or less, 0.300% or less, or 0.200% or less.
ビスマス(Bi)は、鋼の被削性を改善するのに有効な元素である。Bi含有量は0%であってもよいが、このような効果を得るためには、Bi含有量は0.001%以上であることが好ましい。Bi含有量は0.010%以上、0.020%以上、0.030%以上又は0.050%以上であってもよい。一方で、Biを過度に含有しても効果が飽和し、合金コストの増加を招く。したがって、Bi含有量は0.500%以下である。Bi含有量は0.400%以下、0.300%以下又は0.200%以下であってもよい。 [Bi: 0 to 0.500%]
Bismuth (Bi) is an element effective in improving the machinability of steel. The Bi content may be 0%, but in order to obtain such an effect, the Bi content is preferably 0.001% or more. The Bi content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.050% or more. On the other hand, even if Bi is excessively contained, the effect is saturated and the alloy cost increases. Therefore, the Bi content is 0.500% or less. The Bi content may be 0.400% or less, 0.300% or less, or 0.200% or less.
[Pb:0~0.500%]
鉛(Pb)は、切削による温度上昇で溶融してクラックの進展を促進するため、鋼の被削性を改善するのに有効な元素である。Pb含有量は0%であってもよいが、このような効果を得るためには、Pb含有量は0.001%以上であることが好ましい。Pb含有量は0.010%以上、0.020%以上、0.030%以上又は0.050%以上であってもよい。一方で、Pbを過度に含有すると、熱間加工性が低下する場合がある。したがって、Pb含有量は0.500%以下である。Pb含有量は0.400%以下、0.300%以下又は0.200%以下であってもよい。 [Pb: 0 to 0.500%]
Lead (Pb) is an element effective for improving the machinability of steel because it melts when the temperature rises due to cutting and promotes the growth of cracks. The Pb content may be 0%, but in order to obtain such an effect, the Pb content is preferably 0.001% or more. The Pb content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.050% or more. On the other hand, if Pb is excessively contained, the hot workability may be deteriorated. Therefore, the Pb content is 0.500% or less. The Pb content may be 0.400% or less, 0.300% or less, or 0.200% or less.
鉛(Pb)は、切削による温度上昇で溶融してクラックの進展を促進するため、鋼の被削性を改善するのに有効な元素である。Pb含有量は0%であってもよいが、このような効果を得るためには、Pb含有量は0.001%以上であることが好ましい。Pb含有量は0.010%以上、0.020%以上、0.030%以上又は0.050%以上であってもよい。一方で、Pbを過度に含有すると、熱間加工性が低下する場合がある。したがって、Pb含有量は0.500%以下である。Pb含有量は0.400%以下、0.300%以下又は0.200%以下であってもよい。 [Pb: 0 to 0.500%]
Lead (Pb) is an element effective for improving the machinability of steel because it melts when the temperature rises due to cutting and promotes the growth of cracks. The Pb content may be 0%, but in order to obtain such an effect, the Pb content is preferably 0.001% or more. The Pb content may be 0.010% or more, 0.020% or more, 0.030% or more, or 0.050% or more. On the other hand, if Pb is excessively contained, the hot workability may be deteriorated. Therefore, the Pb content is 0.500% or less. The Pb content may be 0.400% or less, 0.300% or less, or 0.200% or less.
本発明の実施形態に係る鋼材において、上記の元素以外の残部は、Fe及び不純物からなる。不純物とは、鋼材を工業的に製造する際に、鉱石やスクラップ等のような原料を始めとして、製造工程の種々の要因によって混入する成分等である。
In the steel material according to the embodiment of the present invention, the balance other than the above elements consists of Fe and impurities. Impurities are components that are mixed in by various factors in the manufacturing process, including raw materials such as ore and scrap, when steel materials are industrially manufactured.
[Z元素の有効量]
本発明の実施形態によれば、Zr及びHfからなるZ元素の有効量は、下記式1の左辺によって求められ、そしてその値は下記式1を満たすようにする。
0.61[Zr]+0.31[Hf]-1.75[O]-3.99[N]-1.74[S] ≧ 0.0003 ・・・式1
ここで、[Zr]、[Hf]、[O]、[N]、及び[S]は、各元素の含有量[質量%]であり、元素を含有しない場合は0である。 [Effective amount of Z element]
According to the embodiment of the present invention, the effective amount of the Z element consisting of Zr and Hf is determined by the left side of the following formula 1, and the value thereof satisfies the following formula 1.
0.61 [Zr] +0.31 [Hf] -1.75 [O] -3.99 [N] -1.74 [S] ≧ 0.0003 ・ ・ ・ Equation 1
Here, [Zr], [Hf], [O], [N], and [S] are the content [mass%] of each element, and are 0 when the element is not contained.
本発明の実施形態によれば、Zr及びHfからなるZ元素の有効量は、下記式1の左辺によって求められ、そしてその値は下記式1を満たすようにする。
0.61[Zr]+0.31[Hf]-1.75[O]-3.99[N]-1.74[S] ≧ 0.0003 ・・・式1
ここで、[Zr]、[Hf]、[O]、[N]、及び[S]は、各元素の含有量[質量%]であり、元素を含有しない場合は0である。 [Effective amount of Z element]
According to the embodiment of the present invention, the effective amount of the Z element consisting of Zr and Hf is determined by the left side of the following formula 1, and the value thereof satisfies the following formula 1.
0.61 [Zr] +0.31 [Hf] -1.75 [O] -3.99 [N] -1.74 [S] ≧ 0.0003 ・ ・ ・ Equation 1
Here, [Zr], [Hf], [O], [N], and [S] are the content [mass%] of each element, and are 0 when the element is not contained.
上記Z元素の有効量を上記式1を満たすようにすることで、鋼中に固溶状態で存在しているこれらの元素の量を増加させることができるので、当該Z元素を粒界に十分な量において偏析させることができ、結果としてPの粒界偏析を低減することが可能となる。より詳しく説明すると、これらのZ元素(以下、単に「Z」ともいう)は、鋼中に存在するO(酸素)、N(窒素)及びS(硫黄)と結びついて、酸化物(ZO2)、窒化物(ZN)及び硫化物(ZS)からなる介在物を形成する傾向がある。当該介在物を形成してしまうと、少なくともこれらの介在物中のZ元素は粒界に偏析することはできない。したがって、Z元素の粒界への偏析を促進して鋼中のPの粒界偏析を低減するためには、介在物を形成せずに鋼中に固溶状態で存在しているZ元素の量(すなわち鋼中のZ元素の固溶量)を増加させる必要がある。
By making the effective amount of the Z element satisfy the above formula 1, the amount of these elements existing in the solid solution state in the steel can be increased, so that the Z element can be sufficiently applied to the grain boundary. It is possible to segregate in a large amount, and as a result, it is possible to reduce the grain boundary segregation of P. More specifically, these Z elements (hereinafter, also simply referred to as “Z”) are combined with O (oxygen), N (nitrogen) and S (sulfur) present in steel to form an oxide (ZO 2 ). , Tends to form inclusions consisting of nitrides (ZN) and sulfides (ZS). Once the inclusions are formed, at least the Z element in these inclusions cannot segregate at the grain boundaries. Therefore, in order to promote the segregation of Z element into the grain boundary and reduce the segregation of P in the steel, the Z element existing in the steel in a solid solution state without forming inclusions is formed. It is necessary to increase the amount (that is, the solid solution amount of the Z element in the steel).
ここで、鋼中のZ元素の固溶量は、鋼中に含まれるZ元素の量から介在物(酸化物、窒化物及び硫化物)を形成するのに消費され得る最大量を差し引くことによって概算することが可能である。そこで、本発明の実施形態においては、このようにして概算される鋼中のPの粒界偏析を低減するのに有効なZ元素の量(すなわち「Z元素の有効量」)は、具体的には下記式Aによって定義される。
Z元素の有効量[原子%]=Σ(M[Fe]/M[Z])×[Z]-(M[Fe]/M[O])×[O]×1/2-(M[Fe]/M[N])×[N]-(M[Fe]/M[S])×[S] ・・・式A
ここで、ZはZr及びHfの各Z元素を表し、M[Z]はZ元素の原子量、M[Fe]はFeの原子量、M[O]はOの原子量、M[N]はNの原子量、M[S]はSの原子量を表し、[Z]、[O]、[N]、及び[S]は、それぞれ対応する元素の含有量[質量%]であり、元素を含有しない場合は0である。 Here, the solid solution amount of the Z element in the steel is obtained by subtracting the maximum amount that can be consumed to form inclusions (oxides, nitrides and sulfides) from the amount of the Z element contained in the steel. It is possible to make an approximation. Therefore, in the embodiment of the present invention, the amount of Z element effective for reducing the grain boundary segregation of P in the steel estimated in this way (that is, "effective amount of Z element") is concrete. Is defined by the following formula A.
Effective amount of Z element [atomic%] = Σ (M [Fe] / M [Z] ) x [Z]-(M [Fe] / M [O] ) x [O] x 1 / 2- (M [ ] Fe] / M [N] ) x [N]-(M [Fe] / M [S] ) x [S] ... Equation A
Here, Z represents each Z element of Zr and Hf, M [Z] is the atomic weight of the Z element, M [Fe] is the atomic weight of Fe, M [O] is the atomic weight of O, and M [N] is N. Atomic weight, M [S] represents the atomic weight of S, and [Z], [O], [N], and [S] are the corresponding element content [mass%], respectively, when no element is contained. Is 0.
Z元素の有効量[原子%]=Σ(M[Fe]/M[Z])×[Z]-(M[Fe]/M[O])×[O]×1/2-(M[Fe]/M[N])×[N]-(M[Fe]/M[S])×[S] ・・・式A
ここで、ZはZr及びHfの各Z元素を表し、M[Z]はZ元素の原子量、M[Fe]はFeの原子量、M[O]はOの原子量、M[N]はNの原子量、M[S]はSの原子量を表し、[Z]、[O]、[N]、及び[S]は、それぞれ対応する元素の含有量[質量%]であり、元素を含有しない場合は0である。 Here, the solid solution amount of the Z element in the steel is obtained by subtracting the maximum amount that can be consumed to form inclusions (oxides, nitrides and sulfides) from the amount of the Z element contained in the steel. It is possible to make an approximation. Therefore, in the embodiment of the present invention, the amount of Z element effective for reducing the grain boundary segregation of P in the steel estimated in this way (that is, "effective amount of Z element") is concrete. Is defined by the following formula A.
Effective amount of Z element [atomic%] = Σ (M [Fe] / M [Z] ) x [Z]-(M [Fe] / M [O] ) x [O] x 1 / 2- (M [ ] Fe] / M [N] ) x [N]-(M [Fe] / M [S] ) x [S] ... Equation A
Here, Z represents each Z element of Zr and Hf, M [Z] is the atomic weight of the Z element, M [Fe] is the atomic weight of Fe, M [O] is the atomic weight of O, and M [N] is N. Atomic weight, M [S] represents the atomic weight of S, and [Z], [O], [N], and [S] are the corresponding element content [mass%], respectively, when no element is contained. Is 0.
上記式Aについて以下に詳しく説明すると、まず、本発明の実施形態に係る鋼材には種々の合金元素が含有されているものの、鋼材全体としてはほぼFeによって構成されているか、あるいは任意選択元素であるNi及び/又はCrを比較的多く含む場合(それぞれの最大含有量は60.00%及び30.00%)には、Feに加えてNi及び/又はCrによってほぼ構成されていることが明らかである。一方で、Ni及びCrの原子量はFeの原子量と同等であることが周知である。このため、たとえ鋼材がNi及び/又はCrを比較的多く含む場合であっても、Zr及びHfの各Z元素の原子%は、近似的には各Z元素の含有量[質量%]にFeの原子量と当該各Z元素の原子量の比を掛け算すること、すなわち(M[Fe]/M[Z])×[Z]によって算出することができる。したがって、(M[Fe]/M[Z])×[Z]によって算出される各Z元素の量を合計することで(すなわちΣ(M[Fe]/M[Z])×[Z]を計算することで)、Z元素全体の原子%を算出することができる。
The above formula A will be described in detail below. First, although the steel material according to the embodiment of the present invention contains various alloying elements, the steel material as a whole is almost composed of Fe or is an optional element. When a certain Ni and / or Cr is contained in a relatively large amount (the maximum contents are 60.00% and 30.00%, respectively), it is clear that it is almost composed of Ni and / or Cr in addition to Fe. Is. On the other hand, it is well known that the atomic weights of Ni and Cr are equivalent to the atomic weights of Fe. Therefore, even when the steel material contains a relatively large amount of Ni and / or Cr, the atomic% of each Z element of Zr and Hf is approximately Fe in the content [mass%] of each Z element. It can be calculated by multiplying the atomic weight of each Z element by the ratio of the atomic weight of each Z element, that is, (M [Fe] / M [Z] ) × [Z]. Therefore, by summing up the amounts of each Z element calculated by (M [ Fe ] / M [Z ] ) × [Z] (that is, Σ (M [Fe] / M [Z] ) × [Z]. By calculation), the atomic% of the entire Z element can be calculated.
次に、Z元素全体の原子%のうち、酸化物(ZO2)、窒化物(ZN)及び硫化物(ZS)を形成するのに消費され得る最大量(原子%)を差し引くことで、Pの粒界偏析を低減するのに有効に作用し得る鋼中のZ元素の量を算出することができる。ここで、酸化物(ZO2)、窒化物(ZN)及び硫化物(ZS)を形成するのに消費され得るZ元素の最大量(原子%)は、上で説明したのと同様の理由から近似的には鋼中のFe、O、N及びSの原子量並びにO、N及びSの含有量を用いて、それぞれ(M[Fe]/M[O])×[O]×1/2、(M[Fe]/M[N])×[N]、及び(M[Fe]/M[S])×[S]として算出することが可能である。したがって、Pの粒界偏析を低減するためのZ元素の有効量は、下記式Aによって定義することができる。
Z元素の有効量[原子%]=Σ(M[Fe]/M[Z])×[Z]-(M[Fe]/M[O])×[O]×1/2-(M[Fe]/M[N])×[N]-(M[Fe]/M[S])×[S] ・・・式A Next, by subtracting the maximum amount (atomic%) that can be consumed to form oxides (ZO 2 ), nitrides (ZN) and sulfides (ZS) from the atomic% of the total Z element, P It is possible to calculate the amount of Z element in the steel that can effectively act to reduce the grain boundary segregation. Here, the maximum amount (atomic%) of Z element that can be consumed to form oxides (ZO 2 ), nitrides (ZN) and sulfides (ZS) is for the same reasons as described above. Approximately, using the atomic weights of Fe, O, N and S and the contents of O, N and S in the steel, (M [Fe] / M [O] ) × [O] × 1/2, respectively. It can be calculated as (M [Fe] / M [N] ) × [N] and (M [Fe] / M [S] ) × [S]. Therefore, the effective amount of the Z element for reducing the grain boundary segregation of P can be defined by the following formula A.
Effective amount of Z element [atomic%] = Σ (M [Fe] / M [Z] ) x [Z]-(M [Fe] / M [O] ) x [O] x 1 / 2- (M [ ] Fe] / M [N] ) x [N]-(M [Fe] / M [S] ) x [S] ... Equation A
Z元素の有効量[原子%]=Σ(M[Fe]/M[Z])×[Z]-(M[Fe]/M[O])×[O]×1/2-(M[Fe]/M[N])×[N]-(M[Fe]/M[S])×[S] ・・・式A Next, by subtracting the maximum amount (atomic%) that can be consumed to form oxides (ZO 2 ), nitrides (ZN) and sulfides (ZS) from the atomic% of the total Z element, P It is possible to calculate the amount of Z element in the steel that can effectively act to reduce the grain boundary segregation. Here, the maximum amount (atomic%) of Z element that can be consumed to form oxides (ZO 2 ), nitrides (ZN) and sulfides (ZS) is for the same reasons as described above. Approximately, using the atomic weights of Fe, O, N and S and the contents of O, N and S in the steel, (M [Fe] / M [O] ) × [O] × 1/2, respectively. It can be calculated as (M [Fe] / M [N] ) × [N] and (M [Fe] / M [S] ) × [S]. Therefore, the effective amount of the Z element for reducing the grain boundary segregation of P can be defined by the following formula A.
Effective amount of Z element [atomic%] = Σ (M [Fe] / M [Z] ) x [Z]-(M [Fe] / M [O] ) x [O] x 1 / 2- (M [ ] Fe] / M [N] ) x [N]-(M [Fe] / M [S] ) x [S] ... Equation A
ここで、Fe、O、N及びS並びに各Z元素の原子量は、それぞれFe:55.845、O:15.9994、N:14.0069、S:32.068、Zr:91.224、Hf:178.49である。したがって、上記式Aに各元素の原子量を代入して整理すると、Z元素の原子%による有効量は近似的には下記式Bによって表すことが可能となる。
有効量=0.61[Zr]+0.31[Hf]-1.75[O]-3.99[N]-1.74[S] ・・・式B
ここで、[Zr]、[Hf]、[O]、[N]、及び[S]は、各元素の含有量[質量%]であり、元素を含有しない場合は0である。 Here, the atomic weights of Fe, O, N and S and each Z element are Fe: 55.845, O: 15.9994, N: 14.0069, S: 32.068, Zr: 91.224, Hf, respectively. It is 178.49. Therefore, by substituting the atomic weight of each element into the above formula A and rearranging it, the effective amount of the Z element in terms of atomic% can be approximately expressed by the following formula B.
Effective amount = 0.61 [Zr] +0.31 [Hf] -1.75 [O] -3.99 [N] -1.74 [S] ... Expression B
Here, [Zr], [Hf], [O], [N], and [S] are the content [mass%] of each element, and are 0 when the element is not contained.
有効量=0.61[Zr]+0.31[Hf]-1.75[O]-3.99[N]-1.74[S] ・・・式B
ここで、[Zr]、[Hf]、[O]、[N]、及び[S]は、各元素の含有量[質量%]であり、元素を含有しない場合は0である。 Here, the atomic weights of Fe, O, N and S and each Z element are Fe: 55.845, O: 15.9994, N: 14.0069, S: 32.068, Zr: 91.224, Hf, respectively. It is 178.49. Therefore, by substituting the atomic weight of each element into the above formula A and rearranging it, the effective amount of the Z element in terms of atomic% can be approximately expressed by the following formula B.
Effective amount = 0.61 [Zr] +0.31 [Hf] -1.75 [O] -3.99 [N] -1.74 [S] ... Expression B
Here, [Zr], [Hf], [O], [N], and [S] are the content [mass%] of each element, and are 0 when the element is not contained.
本発明の実施形態においては、Pの粒界偏析を低減するためには、上記式Bによって求められるZ元素の有効量は0.0003%以上、すなわち下記式1を満たすことが少なくとも必要である。
0.61[Zr]+0.31[Hf]-1.75[O]-3.99[N]-1.74[S] ≧ 0.0003 ・・・式1
Z元素の有効量は、例えば0.0005%以上又は0.0007%以上であってもよく、好ましくは0.0010%以上、より好ましくは0.0015%以上、さらにより好ましくは0.0030%以上、最も好ましくは0.0050%以上又は0.0100%以上である。また、上記式1からも明らかなように、当該有効量を安定的に確保するためには、鋼中のO、N及びSの含有量を極力低減することが好ましい。ここで、Z元素の有効量の上限は特に限定されないが、当該Z元素の有効量を過度に増加させても効果が飽和するとともに、製造コストの上昇(Z元素の含有量増加に伴う合金コストの上昇及び/又はO、N及びSに関する精錬コストの上昇)を招くことになり必ずしも好ましくない。したがって、Z元素の有効量は2.0000%以下であり、例えば1.8000%以下、1.5000%以下、1.2000%以下、1.0000%以下又は0.8000%以下であってもよい。 In the embodiment of the present invention, in order to reduce the grain boundary segregation of P, it is necessary that the effective amount of the Z element determined by the above formula B is 0.0003% or more, that is, at least satisfy the following formula 1. ..
0.61 [Zr] +0.31 [Hf] -1.75 [O] -3.99 [N] -1.74 [S] ≧ 0.0003 ・ ・ ・ Equation 1
The effective amount of the Z element may be, for example, 0.0005% or more or 0.0007% or more, preferably 0.0010% or more, more preferably 0.0015% or more, still more preferably 0.0030%. The above is most preferably 0.0050% or more or 0.0100% or more. Further, as is clear from the above formula 1, in order to stably secure the effective amount, it is preferable to reduce the contents of O, N and S in the steel as much as possible. Here, the upper limit of the effective amount of the Z element is not particularly limited, but even if the effective amount of the Z element is excessively increased, the effect is saturated and the manufacturing cost increases (alloy cost due to the increase in the content of the Z element). And / or an increase in refining cost for O, N and S), which is not always preferable. Therefore, the effective amount of Z element is 2.000% or less, for example, even if it is 1.8000% or less, 1.5000% or less, 1.2000% or less, 1.000% or less, or 0.8000% or less. good.
0.61[Zr]+0.31[Hf]-1.75[O]-3.99[N]-1.74[S] ≧ 0.0003 ・・・式1
Z元素の有効量は、例えば0.0005%以上又は0.0007%以上であってもよく、好ましくは0.0010%以上、より好ましくは0.0015%以上、さらにより好ましくは0.0030%以上、最も好ましくは0.0050%以上又は0.0100%以上である。また、上記式1からも明らかなように、当該有効量を安定的に確保するためには、鋼中のO、N及びSの含有量を極力低減することが好ましい。ここで、Z元素の有効量の上限は特に限定されないが、当該Z元素の有効量を過度に増加させても効果が飽和するとともに、製造コストの上昇(Z元素の含有量増加に伴う合金コストの上昇及び/又はO、N及びSに関する精錬コストの上昇)を招くことになり必ずしも好ましくない。したがって、Z元素の有効量は2.0000%以下であり、例えば1.8000%以下、1.5000%以下、1.2000%以下、1.0000%以下又は0.8000%以下であってもよい。 In the embodiment of the present invention, in order to reduce the grain boundary segregation of P, it is necessary that the effective amount of the Z element determined by the above formula B is 0.0003% or more, that is, at least satisfy the following formula 1. ..
0.61 [Zr] +0.31 [Hf] -1.75 [O] -3.99 [N] -1.74 [S] ≧ 0.0003 ・ ・ ・ Equation 1
The effective amount of the Z element may be, for example, 0.0005% or more or 0.0007% or more, preferably 0.0010% or more, more preferably 0.0015% or more, still more preferably 0.0030%. The above is most preferably 0.0050% or more or 0.0100% or more. Further, as is clear from the above formula 1, in order to stably secure the effective amount, it is preferable to reduce the contents of O, N and S in the steel as much as possible. Here, the upper limit of the effective amount of the Z element is not particularly limited, but even if the effective amount of the Z element is excessively increased, the effect is saturated and the manufacturing cost increases (alloy cost due to the increase in the content of the Z element). And / or an increase in refining cost for O, N and S), which is not always preferable. Therefore, the effective amount of Z element is 2.000% or less, for example, even if it is 1.8000% or less, 1.5000% or less, 1.2000% or less, 1.000% or less, or 0.8000% or less. good.
[結晶方位差が23~45°の粒界におけるZr及びHfの偏析量の総和が0.2atoms/nm2以上]
本発明の実施形態においては、Pの粒界偏析を低減するために、Z元素が所定の量において粒界に偏析する必要がある。本発明の実施形態においては、Z元素すなわちZr及びHfが、結晶方位差が23~45°の粒界にそれらの偏析量の総和が0.2atoms/nm2以上となるような量において偏析している場合には、当該Z元素による効果を十分に発揮することができるため、Pの粒界偏析を確実に低減することができる。上記のZ元素の偏析量の総和は、好ましくは0.3atoms/nm2以上、より好ましくは0.4atoms/nm2以上、さらにより好ましくは0.6atoms/nm2以上、最も好ましくは0.7atoms/nm2以上又は1.0atoms/nm2以上である。上記偏析量の総和の上限は特に限定されないが、当該偏析量を過度に増加させても効果が飽和するとともに、製造コストの上昇(Z元素の含有量増加に伴う合金コストの上昇及び/又はO、N及びSに関する精錬コストの上昇)を招くことになり必ずしも好ましくない。したがって、上記偏析量の総和は5.0atoms/nm2以下であり、例えば4.5atoms/nm2以下、4.0atoms/nm2以下、3.5atoms/nm2以下、3.2atoms/nm2以下又は3.0atoms/nm2以下であってもよい。 [The total amount of segregation of Zr and Hf at grain boundaries with a crystal orientation difference of 23 to 45 ° is 0.2 atoms / nm 2 or more]
In the embodiment of the present invention, in order to reduce the grain boundary segregation of P, it is necessary that the Z element segregates at the grain boundary in a predetermined amount. In the embodiment of the present invention, Z elements, that is, Zr and Hf, are segregated at grain boundaries having a crystal orientation difference of 23 to 45 ° at an amount such that the total segregation amount is 0.2 atoms / nm 2 or more. If this is the case, the effect of the Z element can be sufficiently exerted, so that the grain boundary segregation of P can be reliably reduced. The total segregation amount of the Z element is preferably 0.3 atoms / nm 2 or more, more preferably 0.4 atoms / nm 2 or more, still more preferably 0.6 atoms / nm 2 or more, and most preferably 0.7 atoms. / Nm 2 or more or 1.0 atoms / nm 2 or more. The upper limit of the total sum of segregation amounts is not particularly limited, but even if the segregation amount is excessively increased, the effect is saturated and the manufacturing cost increases (the alloy cost increases due to the increase in the content of Z element and / or O). , Increase in refining cost for N and S), which is not always preferable. Therefore, the total segregation amount is 5.0 atoms / nm 2 or less, for example, 4.5 atoms / nm 2 or less, 4.0 atoms / nm 2 or less, 3.5 atoms / nm 2 or less, 3.2 atoms / nm 2 or less. Alternatively, it may be 3.0 atoms / nm 2 or less.
本発明の実施形態においては、Pの粒界偏析を低減するために、Z元素が所定の量において粒界に偏析する必要がある。本発明の実施形態においては、Z元素すなわちZr及びHfが、結晶方位差が23~45°の粒界にそれらの偏析量の総和が0.2atoms/nm2以上となるような量において偏析している場合には、当該Z元素による効果を十分に発揮することができるため、Pの粒界偏析を確実に低減することができる。上記のZ元素の偏析量の総和は、好ましくは0.3atoms/nm2以上、より好ましくは0.4atoms/nm2以上、さらにより好ましくは0.6atoms/nm2以上、最も好ましくは0.7atoms/nm2以上又は1.0atoms/nm2以上である。上記偏析量の総和の上限は特に限定されないが、当該偏析量を過度に増加させても効果が飽和するとともに、製造コストの上昇(Z元素の含有量増加に伴う合金コストの上昇及び/又はO、N及びSに関する精錬コストの上昇)を招くことになり必ずしも好ましくない。したがって、上記偏析量の総和は5.0atoms/nm2以下であり、例えば4.5atoms/nm2以下、4.0atoms/nm2以下、3.5atoms/nm2以下、3.2atoms/nm2以下又は3.0atoms/nm2以下であってもよい。 [The total amount of segregation of Zr and Hf at grain boundaries with a crystal orientation difference of 23 to 45 ° is 0.2 atoms / nm 2 or more]
In the embodiment of the present invention, in order to reduce the grain boundary segregation of P, it is necessary that the Z element segregates at the grain boundary in a predetermined amount. In the embodiment of the present invention, Z elements, that is, Zr and Hf, are segregated at grain boundaries having a crystal orientation difference of 23 to 45 ° at an amount such that the total segregation amount is 0.2 atoms / nm 2 or more. If this is the case, the effect of the Z element can be sufficiently exerted, so that the grain boundary segregation of P can be reliably reduced. The total segregation amount of the Z element is preferably 0.3 atoms / nm 2 or more, more preferably 0.4 atoms / nm 2 or more, still more preferably 0.6 atoms / nm 2 or more, and most preferably 0.7 atoms. / Nm 2 or more or 1.0 atoms / nm 2 or more. The upper limit of the total sum of segregation amounts is not particularly limited, but even if the segregation amount is excessively increased, the effect is saturated and the manufacturing cost increases (the alloy cost increases due to the increase in the content of Z element and / or O). , Increase in refining cost for N and S), which is not always preferable. Therefore, the total segregation amount is 5.0 atoms / nm 2 or less, for example, 4.5 atoms / nm 2 or less, 4.0 atoms / nm 2 or less, 3.5 atoms / nm 2 or less, 3.2 atoms / nm 2 or less. Alternatively, it may be 3.0 atoms / nm 2 or less.
[Z元素の粒界偏析量の測定]
結晶方位差が23~45°の粒界におけるZ元素の偏析量は、三次元アトムプローブ法を利用して以下のように決定される(例えば、J.Takahashi et al.,「Atomic-scale study on segregation behavior at austenite grain boundaties in boron- and molybdenum-added steels」,Acta Mater.Vol.133,pp.41-54,2017を参照)。まず、EBSD(電子後方散乱回折法)によって、鋼材の板厚1/4t部分から採取した試料中の粒界から結晶方位差が23~45°の粒界を選択する。次に、この粒界からFIB(集束イオンビーム加工)のリフトアウト法によって、微小ブロックを切り出す。そのブロックを針台座にPt蒸着法等によって取り付け、ブロック中の粒界が針先端に位置するようにFIB加工を行う。この針試料を、三次元アトムプローブ法によって測定する。三次元アトムプローブ測定は、通常電極型や局所電極型のどちらでもよく、また測定モードとして電圧モード又はレーザーモードのどちらでもよい。電圧モードの場合は、試料温度が50~70K、印加電圧が3~15kV、DC電圧に対するパルス電圧の比率を示すパルス比は15~25%とする。レーザーモードの場合は、試料温度が30~60K、レーザーパルスエネルギーはパルス比が10~30%相当の値とする。三次元アトムプローブ測定で取得したデータから、専用の三次元構築用ソフトウエアを用いて、粒界部を含む三次元元素マップを得ることができる。粒界位置は、元素が面状に濃化している位置や原子面が不連続になっていることから認識できる。 [Measurement of grain boundary segregation amount of element Z]
The amount of segregation of the Z element at the grain boundaries having a crystal orientation difference of 23 to 45 ° is determined as follows using the three-dimensional atom probe method (for example, J. Takahashi et al., "Atomic-scale study". on segmentation behave or austenite grain boundates in boron-and molybdenum-added steels ”, Acta Matter. Vol. 133, pp. 41-54, 2017). First, by EBSD (electron backscatter diffraction method), grain boundaries having a crystal orientation difference of 23 to 45 ° are selected from grain boundaries in a sample collected from a 1 / 4t portion of a steel material. Next, a minute block is cut out from this grain boundary by a lift-out method of FIB (focused ion beam processing). The block is attached to the needle pedestal by a Pt vapor deposition method or the like, and FIB processing is performed so that the grain boundaries in the block are located at the needle tip. This needle sample is measured by the three-dimensional atom probe method. The three-dimensional atom probe measurement may be either a normal electrode type or a local electrode type, and the measurement mode may be either a voltage mode or a laser mode. In the voltage mode, the sample temperature is 50 to 70 K, the applied voltage is 3 to 15 kV, and the pulse ratio indicating the ratio of the pulse voltage to the DC voltage is 15 to 25%. In the laser mode, the sample temperature is 30 to 60 K, and the laser pulse energy is a value corresponding to a pulse ratio of 10 to 30%. From the data acquired by the 3D atom probe measurement, a 3D element map including the grain boundary can be obtained by using the dedicated 3D construction software. The grain boundary positions can be recognized from the positions where the elements are concentrated in a planar manner and the atomic planes are discontinuous.
結晶方位差が23~45°の粒界におけるZ元素の偏析量は、三次元アトムプローブ法を利用して以下のように決定される(例えば、J.Takahashi et al.,「Atomic-scale study on segregation behavior at austenite grain boundaties in boron- and molybdenum-added steels」,Acta Mater.Vol.133,pp.41-54,2017を参照)。まず、EBSD(電子後方散乱回折法)によって、鋼材の板厚1/4t部分から採取した試料中の粒界から結晶方位差が23~45°の粒界を選択する。次に、この粒界からFIB(集束イオンビーム加工)のリフトアウト法によって、微小ブロックを切り出す。そのブロックを針台座にPt蒸着法等によって取り付け、ブロック中の粒界が針先端に位置するようにFIB加工を行う。この針試料を、三次元アトムプローブ法によって測定する。三次元アトムプローブ測定は、通常電極型や局所電極型のどちらでもよく、また測定モードとして電圧モード又はレーザーモードのどちらでもよい。電圧モードの場合は、試料温度が50~70K、印加電圧が3~15kV、DC電圧に対するパルス電圧の比率を示すパルス比は15~25%とする。レーザーモードの場合は、試料温度が30~60K、レーザーパルスエネルギーはパルス比が10~30%相当の値とする。三次元アトムプローブ測定で取得したデータから、専用の三次元構築用ソフトウエアを用いて、粒界部を含む三次元元素マップを得ることができる。粒界位置は、元素が面状に濃化している位置や原子面が不連続になっていることから認識できる。 [Measurement of grain boundary segregation amount of element Z]
The amount of segregation of the Z element at the grain boundaries having a crystal orientation difference of 23 to 45 ° is determined as follows using the three-dimensional atom probe method (for example, J. Takahashi et al., "Atomic-scale study". on segmentation behave or austenite grain boundates in boron-and molybdenum-added steels ”, Acta Matter. Vol. 133, pp. 41-54, 2017). First, by EBSD (electron backscatter diffraction method), grain boundaries having a crystal orientation difference of 23 to 45 ° are selected from grain boundaries in a sample collected from a 1 / 4t portion of a steel material. Next, a minute block is cut out from this grain boundary by a lift-out method of FIB (focused ion beam processing). The block is attached to the needle pedestal by a Pt vapor deposition method or the like, and FIB processing is performed so that the grain boundaries in the block are located at the needle tip. This needle sample is measured by the three-dimensional atom probe method. The three-dimensional atom probe measurement may be either a normal electrode type or a local electrode type, and the measurement mode may be either a voltage mode or a laser mode. In the voltage mode, the sample temperature is 50 to 70 K, the applied voltage is 3 to 15 kV, and the pulse ratio indicating the ratio of the pulse voltage to the DC voltage is 15 to 25%. In the laser mode, the sample temperature is 30 to 60 K, and the laser pulse energy is a value corresponding to a pulse ratio of 10 to 30%. From the data acquired by the 3D atom probe measurement, a 3D element map including the grain boundary can be obtained by using the dedicated 3D construction software. The grain boundary positions can be recognized from the positions where the elements are concentrated in a planar manner and the atomic planes are discontinuous.
次に、粒界偏析量の定量を行う(例えば、高橋ら,「塗装焼付硬化型鋼板の粒界偏析炭素量の定量観察」,新日鉄技報,No.381,26-30,2004を参照)。この粒界面に垂直に横切るように、10nm×10nm×10nmより大きい選択ボックス、例えば、粒界に平行方向に20nm×20nm、粒界に垂直方向に30nmの選択ボックスを設定し、粒界面に垂直方向にラダーチャートを偏析元素毎に描く(例えば特開2008-261029号公報の図2を参照)。粒界を境に積算原子数が増えた分が偏析原子数を示すことになるため、この値を粒界面積(例えば20nm×20nm)で割り、さらに三次元アトムプローブのイオン検出率で割ることによって、粒界偏析量を示すInterfacial excess値を求めることができる。鋼材中の5箇所について同様の測定を行って得られた、Z元素(Zr及びHf)の粒界偏析量を示すInterfacial excess値の合計値の算術平均を「結晶方位差が23~45°の粒界におけるZ元素(Zr及びHf)の偏析量の総和」として決定する。したがって、本発明の実施形態に係る鋼材は、鋼材中の5箇所を三次元アトムプローブ法によって測定した場合の算術平均において、結晶方位差が23~45°の粒界であって、Zr及びHfの偏析量の総和が0.2atoms/nm2以上である粒界を含む鋼材、又は結晶方位差が23~45°の粒界におけるZr及びHfの偏析量の総和が0.2atoms/nm2以上である鋼材ということもできる。
Next, the amount of grain boundary segregation is quantified (see, for example, Takahashi et al., "Quantitative observation of the amount of grain boundary segregated carbon in coated and baked hardened steel sheets", Nippon Steel Technical Report, No. 381, 26-30, 2004). .. A selection box larger than 10 nm × 10 nm × 10 nm is set so as to cross perpendicular to the grain interface, for example, a selection box of 20 nm × 20 nm parallel to the grain boundary and 30 nm perpendicular to the grain boundary is set and perpendicular to the grain interface. A ladder chart is drawn for each segregating element in the direction (see, for example, FIG. 2 of JP-A-2008-261029). Since the increase in the integrated atomic number with the grain boundary as the boundary indicates the segregated atomic number, divide this value by the grain boundary area (for example, 20 nm × 20 nm) and further divide by the ion detection rate of the three-dimensional atom probe. It is possible to obtain the Interfacial Excess value indicating the amount of grain boundary segregation. The arithmetic average of the total value of the interfacial excess values indicating the amount of grain boundary segregation of the Z element (Zr and Hf) obtained by performing the same measurement at 5 points in the steel material is "a crystal orientation difference of 23 to 45 °." It is determined as "the total amount of segregation of Z elements (Zr and Hf) at the grain boundary". Therefore, the steel material according to the embodiment of the present invention has a grain boundary with a crystal orientation difference of 23 to 45 ° in the arithmetic mean when five points in the steel material are measured by the three-dimensional atom probe method, and Zr and Hf. The total segregation amount of Zr and Hf in the steel material containing grain boundaries with a total segregation amount of 0.2 atoms / nm 2 or more, or the grain boundaries with a crystal orientation difference of 23 to 45 ° is 0.2 atoms / nm 2 or more. It can also be said that it is a steel material.
本発明の実施形態に係る鋼材は、Z元素が粒界に偏析している任意の鋼材であってよく、特に限定されない。本発明の実施形態に係る鋼材は、例えば、厚鋼板、薄鋼板、さらには棒鋼、線材、形鋼、及び鋼管等をも包含するものである。
The steel material according to the embodiment of the present invention may be any steel material in which the Z element is segregated at the grain boundaries, and is not particularly limited. The steel material according to the embodiment of the present invention includes, for example, thick steel plates, thin steel plates, steel bars, wire rods, shaped steels, steel pipes, and the like.
本発明の実施形態に係る鋼材は、最終的な製品の形態等に応じて、当業者に公知の任意の適切な方法によって製造することが可能である。例えば、鋼材が厚鋼板の場合には、その製造方法は、一般に厚鋼板を製造する際に適用される工程を含み、例えば、上で説明した化学組成を有するスラブを鋳造する工程、鋳造されたスラブを熱間圧延する工程、及び得られた圧延材を冷却する工程を含み、必要に応じて焼入れ工程及び焼戻し工程等をさらに含んでいてもよい。本発明の実施形態に係る鋼材の製造工程は、制御圧延と加速冷却を組み合わせた熱加工制御プロセス(TMCP)であってもよい。
The steel material according to the embodiment of the present invention can be manufactured by any suitable method known to those skilled in the art, depending on the form of the final product and the like. For example, when the steel material is a thick steel plate, the manufacturing method includes a step generally applied when manufacturing the thick steel plate, for example, a step of casting a slab having the chemical composition described above, and casting. It includes a step of hot rolling the slab and a step of cooling the obtained rolled material, and may further include a quenching step, a tempering step and the like, if necessary. The steel material manufacturing process according to the embodiment of the present invention may be a thermal processing control process (TMCP) that combines controlled rolling and accelerated cooling.
また、鋼材が薄鋼板の場合には、その製造方法は、一般に薄鋼板を製造する際に適用される工程を含み、例えば、上で説明した化学組成を有するスラブを鋳造する工程、鋳造されたスラブを熱間圧延する工程、及び得られた圧延材を冷却して巻き取る工程、必要に応じて冷間圧延工程、焼鈍工程等をさらに含んでいてもよい。棒鋼や他の鋼材の製造方法においても同様に、一般に棒鋼や他の鋼材を製造する際に適用される工程を含み、例えば、上で説明した化学組成を有する溶鋼を形成する製鋼工程、形成された溶鋼からスラブ、ビレット、ブルーム等を鋳造する工程、鋳造されたスラブ、ビレット、ブルーム等を熱間圧延する工程、及び得られた圧延材を冷却する工程を含み、他の工程は、それらの鋼材を製造するのに当業者に公知の適切な工程を適宜選択し、実施することができる。
Further, when the steel material is a thin steel plate, the manufacturing method includes a step generally applied when manufacturing the thin steel plate, for example, a step of casting a slab having the chemical composition described above, and casting. It may further include a step of hot rolling the slab, a step of cooling and winding the obtained rolled material, a cold rolling step, a baking step and the like, if necessary. Similarly, in the method for producing steel bars and other steel materials, a step generally applied when manufacturing steel bars and other steel materials is included, and for example, a steelmaking process for forming molten steel having the chemical composition described above is formed. It includes a step of casting slabs, billets, blooms, etc. from molten steel, a step of hot rolling the cast slabs, billets, blooms, etc., and a step of cooling the obtained rolled material, and other steps include those steps. Appropriate steps known to those skilled in the art for producing steel materials can be appropriately selected and carried out.
Z元素の粒界への偏析は、熱間圧延工程での熱履歴、又は、熱間圧延工程後の熱処理によって制御することができる。熱間圧延工程での熱履歴でZ元素を粒界に偏析させる場合、各Z元素が偏析する温度と時間の範囲を考慮して、熱間圧延を行い、次いで冷却工程において冷却すればよい。特に限定されないが、例えば、このような熱履歴は、粗圧延及び/又は仕上げ圧延後、850~1100℃の温度範囲において保持する時間を5秒以上とすることを含むものである。「保持」とは、上記の温度範囲内で放冷又は空冷等により徐々に温度が低下する場合を包含するものである。保持時間の上限は、特に限定されないが、例えば1800秒以下であってよい。
The segregation of the Z element into the grain boundaries can be controlled by the heat history in the hot rolling process or the heat treatment after the hot rolling process. When the Z element is segregated at the grain boundary in the heat history in the hot rolling step, the hot rolling may be performed in consideration of the temperature and time range in which each Z element segregates, and then the cooling may be performed in the cooling step. Although not particularly limited, for example, such a thermal history includes setting the holding time in the temperature range of 850 to 1100 ° C. for 5 seconds or more after rough rolling and / or finish rolling. The term "retention" includes a case where the temperature gradually decreases due to cooling, air cooling, or the like within the above temperature range. The upper limit of the holding time is not particularly limited, but may be, for example, 1800 seconds or less.
また、熱間圧延工程及び冷却工程の後に、各Z元素が偏析する温度に加熱し、保持して、冷却する熱処理を施してZ元素を粒界に偏析させることもできる。熱処理を施す場合は、850~1100℃の温度範囲における保持時間を5秒以上、好ましくは10秒以上とし、冷却すればよい。保持時間の上限は、特に限定されないが、例えば1800秒以下又は600秒以下であってよい。熱処理の加熱温度が高い場合、例えば、1200℃以上に加熱し、850~1100℃の温度範囲で保持せずに冷却すると、各Z元素の分布が均質になり、粒界偏析が減少する場合がある。
Further, after the hot rolling step and the cooling step, the Z element can be segregated at the grain boundary by performing a heat treatment of heating, holding and cooling to a temperature at which each Z element segregates. When heat treatment is performed, the holding time in the temperature range of 850 to 1100 ° C. may be 5 seconds or longer, preferably 10 seconds or longer, and cooling may be performed. The upper limit of the holding time is not particularly limited, but may be, for example, 1800 seconds or less or 600 seconds or less. When the heating temperature of the heat treatment is high, for example, if it is heated to 1200 ° C. or higher and cooled without holding it in the temperature range of 850 to 1100 ° C., the distribution of each Z element becomes uniform and the grain boundary segregation may decrease. be.
このような熱間圧延工程の熱履歴又は熱間圧延工程後の熱処理により、Z元素を十分に粒界に偏析させることができるため、その後の焼き戻し処理等によってもPが粒界へ偏析することを抑制することができる。その結果として、焼き戻し脆化等の発生を抑制することができ、それゆえ鋼材の靭性等の特性を顕著に向上させることが可能となる。また、本発明の実施形態に係る鋼材の製造では、Pの粒界偏析を低減するためのZ元素の有効量を確保することが重要であり、そのためにはZ元素と鋼中で介在物を形成し得るO、N及びSの含有量を精錬工程において十分に低減しておくことが極めて重要である。
Since the Z element can be sufficiently segregated to the grain boundaries by the thermal history of the hot rolling process or the heat treatment after the hot rolling process, P is segregated to the grain boundaries even by the subsequent tempering treatment or the like. It can be suppressed. As a result, it is possible to suppress the occurrence of tempering embrittlement and the like, and therefore it is possible to significantly improve the toughness and other properties of the steel material. Further, in the production of the steel material according to the embodiment of the present invention, it is important to secure an effective amount of Z element for reducing the grain boundary segregation of P, and for that purpose, Z element and inclusions in the steel are used. It is extremely important that the contents of O, N and S that can be formed are sufficiently reduced in the refining step.
以下、実施例によって本発明をより詳細に説明するが、本発明はこれらの実施例に何ら限定されるものではない。
Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.
[実施例1~83及び比較例84~90]
まず、種々の化学組成を有するスラブを鋳造し、次いで熱間圧延を圧下率50%以上で実施し、冷却した。次に、得られた圧延材を加熱し、850~1100℃の範囲内の所定の温度で20~50秒保持し、次いで急冷することによりZ元素を粒界に偏析させた鋼材を得た。 [Examples 1 to 83 and Comparative Examples 84 to 90]
First, slabs having various chemical compositions were cast, and then hot rolling was carried out at a rolling reduction of 50% or more and cooled. Next, the obtained rolled material was heated, held at a predetermined temperature in the range of 850 to 1100 ° C. for 20 to 50 seconds, and then rapidly cooled to obtain a steel material in which the Z element was segregated at the grain boundaries.
まず、種々の化学組成を有するスラブを鋳造し、次いで熱間圧延を圧下率50%以上で実施し、冷却した。次に、得られた圧延材を加熱し、850~1100℃の範囲内の所定の温度で20~50秒保持し、次いで急冷することによりZ元素を粒界に偏析させた鋼材を得た。 [Examples 1 to 83 and Comparative Examples 84 to 90]
First, slabs having various chemical compositions were cast, and then hot rolling was carried out at a rolling reduction of 50% or more and cooled. Next, the obtained rolled material was heated, held at a predetermined temperature in the range of 850 to 1100 ° C. for 20 to 50 seconds, and then rapidly cooled to obtain a steel material in which the Z element was segregated at the grain boundaries.
[比較例91]
実施例1と同様にして熱間圧延を行い、冷却後、圧延材を1200℃に加熱して50秒保持し、次いで急冷し、鋼材を得た。実施例及び比較例において得られた各鋼材から採取した試料を分析した化学組成は、下表1に示すとおりである。また、得られた各鋼材におけるZ元素の粒界偏析量は以下の方法によって測定した。 [Comparative Example 91]
Hot rolling was carried out in the same manner as in Example 1, and after cooling, the rolled material was heated to 1200 ° C. and held for 50 seconds, and then rapidly cooled to obtain a steel material. The chemical compositions obtained by analyzing the samples collected from the steel materials obtained in Examples and Comparative Examples are as shown in Table 1 below. The grain boundary segregation amount of the Z element in each of the obtained steel materials was measured by the following method.
実施例1と同様にして熱間圧延を行い、冷却後、圧延材を1200℃に加熱して50秒保持し、次いで急冷し、鋼材を得た。実施例及び比較例において得られた各鋼材から採取した試料を分析した化学組成は、下表1に示すとおりである。また、得られた各鋼材におけるZ元素の粒界偏析量は以下の方法によって測定した。 [Comparative Example 91]
Hot rolling was carried out in the same manner as in Example 1, and after cooling, the rolled material was heated to 1200 ° C. and held for 50 seconds, and then rapidly cooled to obtain a steel material. The chemical compositions obtained by analyzing the samples collected from the steel materials obtained in Examples and Comparative Examples are as shown in Table 1 below. The grain boundary segregation amount of the Z element in each of the obtained steel materials was measured by the following method.
[Z元素の粒界偏析量の測定]
結晶方位差が23~45°の粒界におけるZ元素の偏析量は、三次元アトムプローブ法を利用して決定した。より具体的には、まず、EBSDによって、鋼材の板厚1/4t部分から採取した試料中の粒界から結晶方位差が23~45°の粒界を選択した。次に、この粒界からFIB(集束イオンビーム加工)のリフトアウト法によって、微小ブロックを切り出した。そのブロックを針台座にPt蒸着法によって取り付け、ブロック中の粒界が針先端に位置するようにFIB加工を行った。この針試料を、三次元アトムプローブ法によって測定した(通常電極型、測定モード:電圧モード、試料温度:50~70K、印加電圧:3~15kV、及びパルス比:15~25%)。三次元アトムプローブ測定で取得したデータから、専用の三次元構築用ソフトウエアを用いて粒界部を含む三次元元素マップを得、粒界面に垂直に横切るように、粒界に平行方向に20nm×20nm、粒界に垂直方向に30nmの選択ボックスを設定し、粒界面に垂直方向にラダーチャートを偏析元素毎に描いた。10粒界を境に積算原子数が増えた分が偏析原子数を示すことになるため、この値を粒界面積(20nm×20nm)で割り、さらに三次元アトムプローブのイオン検出率で割ることによって、粒界偏析量を示すInterfacial excess値を求めた。鋼材中の5箇所について同様の測定を行って得られた、Z元素の粒界偏析量を示すInterfacial excess値の合計値の算術平均を「結晶方位差が23~45°の粒界におけるZ元素(Zr及びHfの少なくとも1種)の偏析量の総和」として決定した。 [Measurement of grain boundary segregation amount of element Z]
The amount of segregation of the Z element at the grain boundaries having a crystal orientation difference of 23 to 45 ° was determined by using the three-dimensional atom probe method. More specifically, first, a grain boundary having a crystal orientation difference of 23 to 45 ° was selected from the grain boundaries in the sample collected from the 1 / 4t portion of the steel material by EBSD. Next, a minute block was cut out from this grain boundary by a lift-out method of FIB (focused ion beam processing). The block was attached to the needle pedestal by the Pt vapor deposition method, and FIB processing was performed so that the grain boundaries in the block were located at the needle tip. This needle sample was measured by a three-dimensional atom probe method (normal electrode type, measurement mode: voltage mode, sample temperature: 50 to 70 K, applied voltage: 3 to 15 kV, and pulse ratio: 15 to 25%). From the data acquired by the 3D atom probe measurement, a 3D element map including the grain boundary is obtained using the dedicated 3D construction software, and 20 nm in the direction parallel to the grain boundary so as to cross perpendicular to the grain interface. A selection box of × 20 nm and 30 nm in the direction perpendicular to the grain boundary was set, and a ladder chart was drawn for each segregated element in the direction perpendicular to the grain interface. Since the increase in the cumulative number of atoms at the boundary of 10 grains indicates the number of segregated atoms, divide this value by the grain boundary area (20 nm x 20 nm) and further divide by the ion detection rate of the three-dimensional atom probe. The interfacial excess value indicating the amount of grain boundary segregation was determined by. The arithmetic mean of the total value of the interfacial excess values indicating the amount of grain boundary segregation of Z element obtained by performing the same measurement at 5 points in the steel material is "Z element at the grain boundary with a crystal orientation difference of 23 to 45 °". (At least one of Zr and Hf) was determined as the total amount of segregation.
結晶方位差が23~45°の粒界におけるZ元素の偏析量は、三次元アトムプローブ法を利用して決定した。より具体的には、まず、EBSDによって、鋼材の板厚1/4t部分から採取した試料中の粒界から結晶方位差が23~45°の粒界を選択した。次に、この粒界からFIB(集束イオンビーム加工)のリフトアウト法によって、微小ブロックを切り出した。そのブロックを針台座にPt蒸着法によって取り付け、ブロック中の粒界が針先端に位置するようにFIB加工を行った。この針試料を、三次元アトムプローブ法によって測定した(通常電極型、測定モード:電圧モード、試料温度:50~70K、印加電圧:3~15kV、及びパルス比:15~25%)。三次元アトムプローブ測定で取得したデータから、専用の三次元構築用ソフトウエアを用いて粒界部を含む三次元元素マップを得、粒界面に垂直に横切るように、粒界に平行方向に20nm×20nm、粒界に垂直方向に30nmの選択ボックスを設定し、粒界面に垂直方向にラダーチャートを偏析元素毎に描いた。10粒界を境に積算原子数が増えた分が偏析原子数を示すことになるため、この値を粒界面積(20nm×20nm)で割り、さらに三次元アトムプローブのイオン検出率で割ることによって、粒界偏析量を示すInterfacial excess値を求めた。鋼材中の5箇所について同様の測定を行って得られた、Z元素の粒界偏析量を示すInterfacial excess値の合計値の算術平均を「結晶方位差が23~45°の粒界におけるZ元素(Zr及びHfの少なくとも1種)の偏析量の総和」として決定した。 [Measurement of grain boundary segregation amount of element Z]
The amount of segregation of the Z element at the grain boundaries having a crystal orientation difference of 23 to 45 ° was determined by using the three-dimensional atom probe method. More specifically, first, a grain boundary having a crystal orientation difference of 23 to 45 ° was selected from the grain boundaries in the sample collected from the 1 / 4t portion of the steel material by EBSD. Next, a minute block was cut out from this grain boundary by a lift-out method of FIB (focused ion beam processing). The block was attached to the needle pedestal by the Pt vapor deposition method, and FIB processing was performed so that the grain boundaries in the block were located at the needle tip. This needle sample was measured by a three-dimensional atom probe method (normal electrode type, measurement mode: voltage mode, sample temperature: 50 to 70 K, applied voltage: 3 to 15 kV, and pulse ratio: 15 to 25%). From the data acquired by the 3D atom probe measurement, a 3D element map including the grain boundary is obtained using the dedicated 3D construction software, and 20 nm in the direction parallel to the grain boundary so as to cross perpendicular to the grain interface. A selection box of × 20 nm and 30 nm in the direction perpendicular to the grain boundary was set, and a ladder chart was drawn for each segregated element in the direction perpendicular to the grain interface. Since the increase in the cumulative number of atoms at the boundary of 10 grains indicates the number of segregated atoms, divide this value by the grain boundary area (20 nm x 20 nm) and further divide by the ion detection rate of the three-dimensional atom probe. The interfacial excess value indicating the amount of grain boundary segregation was determined by. The arithmetic mean of the total value of the interfacial excess values indicating the amount of grain boundary segregation of Z element obtained by performing the same measurement at 5 points in the steel material is "Z element at the grain boundary with a crystal orientation difference of 23 to 45 °". (At least one of Zr and Hf) was determined as the total amount of segregation.
[Pの粒界偏析の評価]
Z元素の粒界偏析がPの粒界偏析の低減に与える効果を検証するため、上で得られた各鋼材を550℃及び1200秒の条件下で焼き戻し処理を実施した後のPの粒界偏析量を、Z元素の場合と同様の三次元アトムプローブ法を利用して測定した。その結果を表1に示す。 [Evaluation of P grain boundary segregation]
In order to verify the effect of the grain boundary segregation of the Z element on the reduction of the grain boundary segregation of P, the grains of P after each of the steel materials obtained above was tempered under the conditions of 550 ° C. and 1200 seconds. The amount of field segregation was measured using the same three-dimensional atom probe method as for element Z. The results are shown in Table 1.
Z元素の粒界偏析がPの粒界偏析の低減に与える効果を検証するため、上で得られた各鋼材を550℃及び1200秒の条件下で焼き戻し処理を実施した後のPの粒界偏析量を、Z元素の場合と同様の三次元アトムプローブ法を利用して測定した。その結果を表1に示す。 [Evaluation of P grain boundary segregation]
In order to verify the effect of the grain boundary segregation of the Z element on the reduction of the grain boundary segregation of P, the grains of P after each of the steel materials obtained above was tempered under the conditions of 550 ° C. and 1200 seconds. The amount of field segregation was measured using the same three-dimensional atom probe method as for element Z. The results are shown in Table 1.
本例では、焼き戻し処理後のPの粒界偏析量が0.4atoms/nm2以下の場合を鋼中のPの粒界偏析が低減された鋼材として評価した。表1を参照すると、比較例84~90では、Zr及びHfからなるZ元素の有効量が低かったために、当該Z元素を粒界に偏析させることができず、結果として鋼材中のPの粒界偏析を低減することができなかった。一方、比較例91では、Z元素の有効量は0.0003%よりも高く、それゆえ式1を満足するものであったが、製造工程においてZ元素を粒界に十分に偏析させることができなかったために、鋼材中のPの粒界偏析を低減することができなかった。これとは対照的に、本発明に係る全ての実施例において、Z元素の有効量を0.0003%以上とし、さらには当該Z元素を粒界に十分に偏析させることで、鋼材中のPの粒界偏析を低減することができた。
In this example, the case where the grain boundary segregation amount of P after the tempering treatment was 0.4 atoms / nm 2 or less was evaluated as a steel material in which the grain boundary segregation of P in the steel was reduced. Referring to Table 1, in Comparative Examples 84 to 90, since the effective amount of the Z element composed of Zr and Hf was low, the Z element could not be segregated at the grain boundaries, and as a result, the grains of P in the steel material could not be segregated. The field segregation could not be reduced. On the other hand, in Comparative Example 91, the effective amount of the Z element was higher than 0.0003%, and therefore satisfied the formula 1, but the Z element could be sufficiently segregated at the grain boundaries in the manufacturing process. Therefore, it was not possible to reduce the grain boundary segregation of P in the steel material. In contrast, in all the embodiments of the present invention, the effective amount of the Z element is 0.0003% or more, and the Z element is sufficiently segregated at the grain boundaries to allow P in the steel material. It was possible to reduce the grain boundary segregation.
本発明の実施形態に係る鋼材は、Z元素が粒界偏析した熱間圧延後の鋼材、例えば、橋梁、建築、造船及び圧力容器等の用途に使用される厚鋼板、自動車及び家電等の用途に使用される薄鋼板、さらには棒鋼、線材、形鋼、及び鋼管等をも包含するものである。これらの材料において本発明の実施形態に係る鋼材を適用した場合には、鋼中のPの粒界偏析が十分に低減されているため、当該Pの粒界偏析に関連する鋼材の特性、例えば、靭性、延性、耐食性、溶接性などの特性を顕著に改善することが可能である。
The steel material according to the embodiment of the present invention is a steel material after hot rolling in which the Z element is segregated at the grain boundary, for example, thick steel sheets used for bridges, construction, shipbuilding, pressure vessels, etc., automobiles, home appliances, etc. It also includes thin steel plates used in the above, as well as steel bars, wire rods, shaped steels, steel pipes, and the like. When the steel material according to the embodiment of the present invention is applied to these materials, the grain boundary segregation of P in the steel is sufficiently reduced, so that the characteristics of the steel material related to the grain boundary segregation of P, for example, , Toughness, ductility, corrosion resistance, weldability and other properties can be significantly improved.
Claims (5)
- 質量%で、
C:0.001~1.000%、
Si:0.01~3.00%、
Mn:0.10~4.50%、
P:0.300%以下、
S:0.0300%以下、
Al:0.001~5.000%、
N:0.2000%以下、
O:0.0100%以下、
Zr:0~0.8000%、及びHf:0~0.8000%からなる群より選択される少なくとも1種のZ元素、
Nb:0~3.000%、
Ti:0~0.500%、
Ta:0~0.500%、
V:0~1.00%、
Cu:0~3.00%、
Ni:0~60.00%、
Cr:0~30.00%、
Mo:0~5.00%、
W:0~2.00%、
B:0~0.0200%、
Co:0~3.00%、
Be:0~0.050%、
Ag:0~0.500%、
Ca:0~0.0500%、
Mg:0~0.0500%、
La、Ce、Nd、Y、Pm、Pr、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、及びScの少なくとも1種:合計で0~0.5000%、
Sn:0~0.300%、
Sb:0~0.300%、
Te:0~0.100%、
Se:0~0.100%、
As:0~0.050%、
Bi:0~0.500%、
Pb:0~0.500%、並びに
残部:Fe及び不純物からなり、
下記式1を満たす化学組成を有し、
結晶方位差が23~45°の粒界であって、Zr及びHfの偏析量の総和が0.2atoms/nm2以上である粒界を含む、鋼材。
0.61[Zr]+0.31[Hf]-1.75[O]-3.99[N]-1.74[S] ≧ 0.0003 ・・・式1
ここで、[Zr]、[Hf]、[O]、[N]、及び[S]は、各元素の含有量[質量%]であり、元素を含有しない場合は0である。 By mass%,
C: 0.001 to 1.000%,
Si: 0.01-3.00%,
Mn: 0.10 to 4.50%,
P: 0.300% or less,
S: 0.0300% or less,
Al: 0.001-5.000%,
N: 0.2000% or less,
O: 0.0100% or less,
At least one Z element selected from the group consisting of Zr: 0 to 0.8000% and Hf: 0 to 0.8000%.
Nb: 0-3.000%,
Ti: 0 to 0.500%,
Ta: 0 to 0.500%,
V: 0 to 1.00%,
Cu: 0 to 3.00%,
Ni: 0-60.00%,
Cr: 0 to 30.00%,
Mo: 0 to 5.00%,
W: 0 to 2.00%,
B: 0-0.0200%,
Co: 0 to 3.00%,
Be: 0 to 0.050%,
Ag: 0 to 0.500%,
Ca: 0-0.0500%,
Mg: 0-0.0500%,
At least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc: 0 to 0.5000% in total.
Sn: 0 to 0.300%,
Sb: 0 to 0.300%,
Te: 0 to 0.100%,
Se: 0 to 0.100%,
As: 0 to 0.050%,
Bi: 0 to 0.500%,
Pb: 0 to 0.500%, and the balance: Fe and impurities.
It has a chemical composition that satisfies the following formula 1 and has a chemical composition.
A steel material containing grain boundaries having a crystal orientation difference of 23 to 45 ° and a total segregation amount of Zr and Hf of 0.2 atoms / nm 2 or more.
0.61 [Zr] +0.31 [Hf] -1.75 [O] -3.99 [N] -1.74 [S] ≧ 0.0003 ・ ・ ・ Equation 1
Here, [Zr], [Hf], [O], [N], and [S] are the content [mass%] of each element, and are 0 when the element is not contained. - 前記化学組成が、質量%で、
Nb:0.003~3.000%、
Ti:0.005~0.500%、
Ta:0.001~0.500%、
V:0.001~1.00%、
Cu:0.001~3.00%、
Ni:0.001~60.00%、
Cr:0.001~30.00%、
Mo:0.001~5.00%、
W:0.001~2.00%、
B:0.0001~0.0200%、
Co:0.001~3.00%、
Be:0.0003~0.050%、及び
Ag:0.001~0.500%
のうち1種又は2種以上を含む、請求項1に記載の鋼材。 The chemical composition is by mass%.
Nb: 0.003 to 3.000%,
Ti: 0.005 to 0.500%,
Ta: 0.001 to 0.500%,
V: 0.001 to 1.00%,
Cu: 0.001 to 3.00%,
Ni: 0.001 to 60.00%,
Cr: 0.001 to 30.00%,
Mo: 0.001 to 5.00%,
W: 0.001 to 2.00%,
B: 0.0001-0.0200%,
Co: 0.001 to 3.00%,
Be: 0.0003 to 0.050%, and Ag: 0.001 to 0.500%
The steel material according to claim 1, which comprises one or more of the above. - 前記化学組成が、質量%で、
Ca:0.0001~0.0500%、
Mg:0.0001~0.0500%、並びに
La、Ce、Nd、Y、Pm、Pr、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、及びScの少なくとも1種:合計で0.0001~0.5000%
のうち1種又は2種以上を含む、請求項1又は2に記載の鋼材。 The chemical composition is by mass%.
Ca: 0.0001-0.0500%,
Mg: 0.0001 to 0.0500%, and at least one of La, Ce, Nd, Y, Pm, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sc. : 0.0001 to 0.5000% in total
The steel material according to claim 1 or 2, which comprises one or more of the above. - 前記化学組成が、質量%で、
Sn:0.001~0.300%、及び
Sb:0.001~0.300%
のうち1種又は2種を含む、請求項1~3のいずれか1項に記載の鋼材。 The chemical composition is by mass%.
Sn: 0.001 to 0.300%, and Sb: 0.001 to 0.300%
The steel material according to any one of claims 1 to 3, which comprises one or two of the above. - 前記化学組成が、質量%で、
Te:0.001~0.100%、
Se:0.001~0.100%、
As:0.001~0.050%、
Bi:0.001~0.500%、及び
Pb:0.001~0.500%
のうち1種又は2種以上を含む、請求項1~4のいずれか1項に記載の鋼材。 The chemical composition is by mass%.
Te: 0.001 to 0.100%,
Se: 0.001 to 0.100%,
As: 0.001 to 0.050%,
Bi: 0.001 to 0.500%, and Pb: 0.001 to 0.500%
The steel material according to any one of claims 1 to 4, which comprises one or more of the two or more.
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JPH09249935A (en) * | 1996-03-13 | 1997-09-22 | Sumitomo Metal Ind Ltd | High strength steel material excellent in sulfide stress cracking resistance and its production |
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