CA2886286C - Method for producing cast steel having high wear resistance and steel having said characteristics - Google Patents
Method for producing cast steel having high wear resistance and steel having said characteristics Download PDFInfo
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- CA2886286C CA2886286C CA2886286A CA2886286A CA2886286C CA 2886286 C CA2886286 C CA 2886286C CA 2886286 A CA2886286 A CA 2886286A CA 2886286 A CA2886286 A CA 2886286A CA 2886286 C CA2886286 C CA 2886286C
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 107
- 239000010959 steel Substances 0.000 title claims abstract description 107
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 19
- 229910001208 Crucible steel Inorganic materials 0.000 title claims description 27
- 238000000034 method Methods 0.000 claims abstract description 39
- 239000000203 mixture Substances 0.000 claims abstract description 37
- 238000005065 mining Methods 0.000 claims abstract description 32
- 239000000126 substance Substances 0.000 claims abstract description 30
- 238000010438 heat treatment Methods 0.000 claims abstract description 19
- 238000005299 abrasion Methods 0.000 claims abstract description 17
- 238000002844 melting Methods 0.000 claims abstract description 14
- 230000008018 melting Effects 0.000 claims abstract description 14
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 13
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 9
- 229910052796 boron Inorganic materials 0.000 claims abstract description 7
- 229910052742 iron Inorganic materials 0.000 claims abstract description 6
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 5
- 229910052787 antimony Inorganic materials 0.000 claims abstract description 4
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 4
- 229910052718 tin Inorganic materials 0.000 claims abstract description 4
- 229910052721 tungsten Inorganic materials 0.000 claims abstract description 4
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 4
- 229910001563 bainite Inorganic materials 0.000 claims description 21
- 238000001816 cooling Methods 0.000 claims description 16
- 238000000137 annealing Methods 0.000 claims description 15
- 239000011651 chromium Substances 0.000 claims description 15
- 238000000227 grinding Methods 0.000 claims description 11
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 8
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 6
- 230000006698 induction Effects 0.000 claims description 6
- 239000010955 niobium Substances 0.000 claims description 5
- 229910052684 Cerium Inorganic materials 0.000 claims description 4
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims description 4
- 229910052746 lanthanum Inorganic materials 0.000 claims description 4
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims description 4
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 claims description 3
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 claims description 3
- 239000011822 basic refractory Substances 0.000 claims description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims 2
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 claims 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims 2
- 239000010937 tungsten Substances 0.000 claims 2
- 239000011701 zinc Substances 0.000 claims 2
- 239000002253 acid Substances 0.000 claims 1
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 9
- 229910052710 silicon Inorganic materials 0.000 abstract description 8
- 229910052748 manganese Inorganic materials 0.000 abstract description 7
- 229910052719 titanium Inorganic materials 0.000 abstract description 6
- 229910052726 zirconium Inorganic materials 0.000 abstract description 6
- 229910052750 molybdenum Inorganic materials 0.000 abstract description 5
- 229910052782 aluminium Inorganic materials 0.000 abstract description 4
- 229910052759 nickel Inorganic materials 0.000 abstract description 3
- 229910052745 lead Inorganic materials 0.000 abstract description 2
- 229910052802 copper Inorganic materials 0.000 abstract 1
- 229910052698 phosphorus Inorganic materials 0.000 abstract 1
- 229910052761 rare earth metal Inorganic materials 0.000 abstract 1
- 150000002910 rare earth metals Chemical class 0.000 abstract 1
- 235000019589 hardness Nutrition 0.000 description 40
- 229910045601 alloy Inorganic materials 0.000 description 12
- 239000000956 alloy Substances 0.000 description 12
- 238000007792 addition Methods 0.000 description 10
- 239000011572 manganese Substances 0.000 description 10
- 238000001556 precipitation Methods 0.000 description 10
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 9
- 229910000734 martensite Inorganic materials 0.000 description 9
- 239000010936 titanium Substances 0.000 description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 8
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 150000001247 metal acetylides Chemical class 0.000 description 7
- 239000010703 silicon Substances 0.000 description 7
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 6
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 6
- 229910001149 41xx steel Inorganic materials 0.000 description 5
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 5
- 230000002411 adverse Effects 0.000 description 5
- 230000008901 benefit Effects 0.000 description 5
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 4
- 229910001566 austenite Inorganic materials 0.000 description 4
- 238000005266 casting Methods 0.000 description 4
- 239000011733 molybdenum Substances 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 239000002893 slag Substances 0.000 description 3
- 239000006104 solid solution Substances 0.000 description 3
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 2
- 229910001567 cementite Inorganic materials 0.000 description 2
- 238000004581 coalescence Methods 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 2
- 230000000670 limiting effect Effects 0.000 description 2
- 229910001338 liquidmetal Inorganic materials 0.000 description 2
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 229910001562 pearlite Inorganic materials 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 230000000717 retained effect Effects 0.000 description 2
- 238000005482 strain hardening Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910001069 Ti alloy Inorganic materials 0.000 description 1
- 229910001093 Zr alloy Inorganic materials 0.000 description 1
- 239000011820 acidic refractory Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000009412 basement excavation Methods 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 230000009931 harmful effect Effects 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000004901 spalling Methods 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Classifications
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
- C21D1/20—Isothermal quenching, e.g. bainitic hardening
-
- 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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- 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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- 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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- 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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/28—Normalising
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
-
- 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
-
- 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/22—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for drills; for milling cutters; for machine cutting tools
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
- Crushing And Grinding (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Abstract
Provided is a method for producing steel having high wear resistance, a mainly bainitic microstructure, and a balance of tensile strength and hardness for large pieces in mining operations the chemical composition of which steel, in weight percentage, comprises: 0.30-0.40% C, 0.50-1.30% Si, 0.60-1.40%
Mn, 2.30-3.20% Cr, 0.0-1.00% Ni, 0.25-0.70% Mo, 0.0-0.50% Cu, 0.0-0.10% Al, 0.0-0.10% Ti, 0.0-0.10% Zr, <0.050% P, <0.050% S, <0.030% N, optionally <0.050% Nb, optionally 0.0005-0.005% B, optionally 0.015-0.080% rare earth metals, residual contents of W, V, Sn, Sb, Pb and Zn of <0.020%, and the balance in iron.
The method includes melting and heat treatment. The resulting steel exhibits a suitable balance of the chemical composition, tensile strength and hardenability for complete hardening in large cast pieces, typically up to 17 inches thick, with a preferable Brinell hardness of 385-495 BHN and excellent resistance to wear by abrasion impact.
Mn, 2.30-3.20% Cr, 0.0-1.00% Ni, 0.25-0.70% Mo, 0.0-0.50% Cu, 0.0-0.10% Al, 0.0-0.10% Ti, 0.0-0.10% Zr, <0.050% P, <0.050% S, <0.030% N, optionally <0.050% Nb, optionally 0.0005-0.005% B, optionally 0.015-0.080% rare earth metals, residual contents of W, V, Sn, Sb, Pb and Zn of <0.020%, and the balance in iron.
The method includes melting and heat treatment. The resulting steel exhibits a suitable balance of the chemical composition, tensile strength and hardenability for complete hardening in large cast pieces, typically up to 17 inches thick, with a preferable Brinell hardness of 385-495 BHN and excellent resistance to wear by abrasion impact.
Description
=
METHOD FOR PRODUCING CAST STEEL HAVING HIGH WEAR
RESISTANCE AND STEEL HAVING SAID CHARACTERISTICS
Field of application The present invention relates to the field of wear-resistant metallic materials, especially cast steels resistant to wear by abrasion and impact for mining applications. More particularly, the present invention relates to a method for producing cast steel, by which a wear-resistant steel is obtained, with predominantly bainite microstructure and a suitable balance of toughness and hardness for use thereof in mining applications, such as grinding, crushing and all those applications that require large components with high resistance to wear by abrasion and impact. Even more particularly, the present invention relates to a cast steel of predominantly bainite structure, with a suitable balance of toughness and hardness and resistant to wear, to be used in the applications mentioned above.
The technical problem Various methods for producing steels for mining applications are known in the prior art. However, the useful life of the components obtained by these methods is unable to meet production requirements. In particular, the known methods do not provide steels whose hardenability is sufficient to ensure high hardness over the entire cross section of components of large thickness made with this steel.
Solutions in the prior art No methods have been identified for producing cast steels that are able to provide an alloy with the necessary hardenability and hardness for use thereof in mining applications that require large components with
METHOD FOR PRODUCING CAST STEEL HAVING HIGH WEAR
RESISTANCE AND STEEL HAVING SAID CHARACTERISTICS
Field of application The present invention relates to the field of wear-resistant metallic materials, especially cast steels resistant to wear by abrasion and impact for mining applications. More particularly, the present invention relates to a method for producing cast steel, by which a wear-resistant steel is obtained, with predominantly bainite microstructure and a suitable balance of toughness and hardness for use thereof in mining applications, such as grinding, crushing and all those applications that require large components with high resistance to wear by abrasion and impact. Even more particularly, the present invention relates to a cast steel of predominantly bainite structure, with a suitable balance of toughness and hardness and resistant to wear, to be used in the applications mentioned above.
The technical problem Various methods for producing steels for mining applications are known in the prior art. However, the useful life of the components obtained by these methods is unable to meet production requirements. In particular, the known methods do not provide steels whose hardenability is sufficient to ensure high hardness over the entire cross section of components of large thickness made with this steel.
Solutions in the prior art No methods have been identified for producing cast steels that are able to provide an alloy with the necessary hardenability and hardness for use thereof in mining applications that require large components with
- 2 -high resistance to wear by abrasion and impact, such as grinding and crushing; and with increased resistance to wear by abrasion and impact, such as is provided by the present invention.
In general terms, the cast steels that are usually employed in the aforementioned mining applications may be classified as: i) austenitic steels of the Hadfield type; ii) low-alloy Cr-Mo steels with predominantly pearlitic structure; and iii) low-alloy steels with low to medium carbon content with predominantly martensitic microstructure. None of these steels effectively solves the aforementioned problems, as is explained in detail hereunder.
The austenitic manganese steels of the Hadfield type, such as those described in standard ASTM A128, are produced by heat treatment for solution of carbides and water quenching, obtaining a Brinell hardness in the as-heat-treated condition of about 200 BHN. Moreover, these cast steels possess a high capacity for hardening by cold working, and may reach a hardness on the worked surface of up to 450 BHN. Moreover, in view of the increased toughness of these steels, they are mainly used in coatings for ore crushing equipment.
However, when the mechanical stress is not sufficient to produce high hardening by cold working, austenitic manganese steels inevitably display low abrasive wear resistance, greatly reducing the useful life of components made with said steels.
For their part, low-alloy Cr-Mo steels with predominantly pearlitic microstructure are made by a normalizing and annealing heat treatment, reaching Brinell hardnesses in the range 275-400 BHN. These steels have been widely used as cladding for SAG mills over the course of the last 30 years with acceptable
In general terms, the cast steels that are usually employed in the aforementioned mining applications may be classified as: i) austenitic steels of the Hadfield type; ii) low-alloy Cr-Mo steels with predominantly pearlitic structure; and iii) low-alloy steels with low to medium carbon content with predominantly martensitic microstructure. None of these steels effectively solves the aforementioned problems, as is explained in detail hereunder.
The austenitic manganese steels of the Hadfield type, such as those described in standard ASTM A128, are produced by heat treatment for solution of carbides and water quenching, obtaining a Brinell hardness in the as-heat-treated condition of about 200 BHN. Moreover, these cast steels possess a high capacity for hardening by cold working, and may reach a hardness on the worked surface of up to 450 BHN. Moreover, in view of the increased toughness of these steels, they are mainly used in coatings for ore crushing equipment.
However, when the mechanical stress is not sufficient to produce high hardening by cold working, austenitic manganese steels inevitably display low abrasive wear resistance, greatly reducing the useful life of components made with said steels.
For their part, low-alloy Cr-Mo steels with predominantly pearlitic microstructure are made by a normalizing and annealing heat treatment, reaching Brinell hardnesses in the range 275-400 BHN. These steels have been widely used as cladding for SAG mills over the course of the last 30 years with acceptable
- 3 -results, without undergoing large modifications.
Despite the foregoing, owing to the global trend in the mining industry to use ore processing equipment of larger size, added to the ever-increasing mechanical stress to which the components are subjected, the "acceptable results" currently obtained with Cr-Mo steels are inadequate. In view of this, the use of low-alloy Cr-Mo steels with predominantly pearlitic microstructure is limited, since it is not possible to increase their wear resistance by increasing the hardness, without having an adverse effect on toughness. Consequently, the use of these alloys under the current conditions inevitably increases the probability of failure.
Finally, another type of steel commonly used in the mining industry corresponds to the low-alloy steels with low to medium carbon content with predominantly martensitic microstructure. These steels are produced by a heat treatment of hardening and annealing, reaching Brinell hardnesses in the range 321-551 BHN, depending on the specific carbon content of the alloy and the conditions employed in heat treatment. At present, these steels are widely used in cavities of crushers, shovel teeth of earth-moving machinery, discharge chutes and antiwear plates, all these components having thicknesses typically of less than 8 inches (20.3 cm). However, since these steels do not possess sufficient hardenability, it is not possible to guarantee constant high hardness through the cross section of the component, from the surface to the center, for components with thicknesses above 6 inches (15.2 cm). To solve the above problem, increasing the content of carbon and of alloying elements has been tried. However, it has been found that this route causes a considerable decrease in toughness. Moreover, low-alloy steels with low to medium carbon content
Despite the foregoing, owing to the global trend in the mining industry to use ore processing equipment of larger size, added to the ever-increasing mechanical stress to which the components are subjected, the "acceptable results" currently obtained with Cr-Mo steels are inadequate. In view of this, the use of low-alloy Cr-Mo steels with predominantly pearlitic microstructure is limited, since it is not possible to increase their wear resistance by increasing the hardness, without having an adverse effect on toughness. Consequently, the use of these alloys under the current conditions inevitably increases the probability of failure.
Finally, another type of steel commonly used in the mining industry corresponds to the low-alloy steels with low to medium carbon content with predominantly martensitic microstructure. These steels are produced by a heat treatment of hardening and annealing, reaching Brinell hardnesses in the range 321-551 BHN, depending on the specific carbon content of the alloy and the conditions employed in heat treatment. At present, these steels are widely used in cavities of crushers, shovel teeth of earth-moving machinery, discharge chutes and antiwear plates, all these components having thicknesses typically of less than 8 inches (20.3 cm). However, since these steels do not possess sufficient hardenability, it is not possible to guarantee constant high hardness through the cross section of the component, from the surface to the center, for components with thicknesses above 6 inches (15.2 cm). To solve the above problem, increasing the content of carbon and of alloying elements has been tried. However, it has been found that this route causes a considerable decrease in toughness. Moreover, low-alloy steels with low to medium carbon content
- 4 -require a greater cooling rate to obtain a martensitic structure, usually employing water, oil or forced air as the quenching medium. This not only gives rise to higher costs of manufacture, but also hampers the production of large components or those with complex geometry with large changes of section.
Thus, although in the prior art there are methods for producing steels for mining applications, the inventors have not detected any disclosure of a method capable of producing a cast steel of the composition and microstructure specified in the present invention and which in addition offers the aforementioned advantages.
As an example, document JP 2000 328180 of Tamura Akira et al. relates to a wear-resistant cast steel of predominantly martensitic microstructure, to be used in components of mills used by the cement industry, ceramic industry, etc. Both the chemical composition and the microstructure of this steel are substantially different from those of the steel obtained by the method of the present invention. The steel described in JP 2000 328180 has a chromium content preferably in the range 3.8-4.3% w/w. Moreover, said document teaches that a chromium content below 3.01 w/w adversely affects the hardenability of the steel. In contrast, the present invention describes steels with predominantly bainite microstructure with chromium concentrations in the range 2.3-3.2% w/w and with adequate hardenability and hardness in large components.
In addition, the steel described in document JP
2000 328180 does not disclose microadditions of titanium and zirconium, as envisaged in the present invention. This document also does not disclose optional additions of niobium, boron and/or rare earths.
Thus, although in the prior art there are methods for producing steels for mining applications, the inventors have not detected any disclosure of a method capable of producing a cast steel of the composition and microstructure specified in the present invention and which in addition offers the aforementioned advantages.
As an example, document JP 2000 328180 of Tamura Akira et al. relates to a wear-resistant cast steel of predominantly martensitic microstructure, to be used in components of mills used by the cement industry, ceramic industry, etc. Both the chemical composition and the microstructure of this steel are substantially different from those of the steel obtained by the method of the present invention. The steel described in JP 2000 328180 has a chromium content preferably in the range 3.8-4.3% w/w. Moreover, said document teaches that a chromium content below 3.01 w/w adversely affects the hardenability of the steel. In contrast, the present invention describes steels with predominantly bainite microstructure with chromium concentrations in the range 2.3-3.2% w/w and with adequate hardenability and hardness in large components.
In addition, the steel described in document JP
2000 328180 does not disclose microadditions of titanium and zirconium, as envisaged in the present invention. This document also does not disclose optional additions of niobium, boron and/or rare earths.
- 5 -Moreover, document JP 09 170017 of IIHARA Katsuyuki et al. relates to a rolled steel of high strength and toughness that has a predominantly bainite microstructure. However, both the chemical composition of this steel and the method for producing it differ from those disclosed for the steel obtained by the method of the present invention. As an example, the steel described in JP 09 170017 has a higher carbon content and a lower content of silicon and manganese than the steel of the invention. Moreover, it has addition of vanadium for controlling grain size.
Although the bainitic steel of high strength and toughness described in JP 09 170017 uses microalloying elements to obtain a fine bainite microstructure, it has a lower content of silicon and manganese to ensure high toughness, and accordingly it does not develop sufficient hardness, hardenability and wear resistance for use in conditions of abrasion and severe impact in mining operations.
US patent 7,662,247 of HU Kaihua discloses wear-resistant cast steels with a predominantly martensitic microstructure that includes films of austenite for improving toughness, and the method for producing same.
For its part, US patent 3,973,951 of SATSUMABAYASHI
Kazuyoshi et al. discloses a cast steel of high wear resistance and toughness for use as nails, tips, blades or other tools for excavation in construction industry machinery.
Although both documents disclose steels with increased toughness, the high silicon concentration in these steels (1.40-2.05% w/w) has an adverse effect on the manufacture of components with large thickness, since it promotes the occurrence of phenomena of hot crackTing during solidification of the components.
Although the bainitic steel of high strength and toughness described in JP 09 170017 uses microalloying elements to obtain a fine bainite microstructure, it has a lower content of silicon and manganese to ensure high toughness, and accordingly it does not develop sufficient hardness, hardenability and wear resistance for use in conditions of abrasion and severe impact in mining operations.
US patent 7,662,247 of HU Kaihua discloses wear-resistant cast steels with a predominantly martensitic microstructure that includes films of austenite for improving toughness, and the method for producing same.
For its part, US patent 3,973,951 of SATSUMABAYASHI
Kazuyoshi et al. discloses a cast steel of high wear resistance and toughness for use as nails, tips, blades or other tools for excavation in construction industry machinery.
Although both documents disclose steels with increased toughness, the high silicon concentration in these steels (1.40-2.05% w/w) has an adverse effect on the manufacture of components with large thickness, since it promotes the occurrence of phenomena of hot crackTing during solidification of the components.
- 6 -Additionally, patents US 5,382,307 of KAGEYAMA Hideaki et al., US 5,676,772 of KOBAYASHI Kazutaka et al. and US 6,254,696 of UEDA Masaharu et al. describe steels used for making railway tracks with high strength and toughness, resistant to contact fatigue, and that are manufactured by a process of melting, hot rolling and normalizing in forced air. These steels differ from the steels of the present invention in that, although they possess high toughness, they do not have a suitable balance of chemical composition that allows them to obtain a high hardness that is practically constant through the cross section in components with large thickness, despite the fact that high contents of manganese, silicon and/or nickel are specified.
Finally, the steel obtained by the method of the invention also differs from other bainitic steels, such as the carbide-free steels described in US 2010/0294401 of Gonzalo Gomez et al. and US 5,879,474 of BHADESHIA
Harshad et al. In contrast to the steel of the invention, the carbide-free bainitic steels of these documents have contents of manganese, silicon and/or aluminum above 1.50% w/w for promoting the presence of bainite and inhibiting the precipitation of cementite, and moreover have a microstructure with high contents of retained austenite. This retained austenite could optionally be transformed to martensite under the action of events with severe impact, causing phenomena of surface fatigue with large losses of material by a mechanism of accelerated wear known as spalling.
The present invention provides a bainitic cast steel that overcomes all the drawbacks mentioned above, since it possesses suitable wear resistance and a suitable balance between toughness and hardness, and is useful in mining applications that require large components with high resistance to wear by abrasion and impact,
Finally, the steel obtained by the method of the invention also differs from other bainitic steels, such as the carbide-free steels described in US 2010/0294401 of Gonzalo Gomez et al. and US 5,879,474 of BHADESHIA
Harshad et al. In contrast to the steel of the invention, the carbide-free bainitic steels of these documents have contents of manganese, silicon and/or aluminum above 1.50% w/w for promoting the presence of bainite and inhibiting the precipitation of cementite, and moreover have a microstructure with high contents of retained austenite. This retained austenite could optionally be transformed to martensite under the action of events with severe impact, causing phenomena of surface fatigue with large losses of material by a mechanism of accelerated wear known as spalling.
The present invention provides a bainitic cast steel that overcomes all the drawbacks mentioned above, since it possesses suitable wear resistance and a suitable balance between toughness and hardness, and is useful in mining applications that require large components with high resistance to wear by abrasion and impact,
- 7 -especially those associated with crushing and grinding.
Brief description of the invention The method and the steel of the present invention provide a solution to the limitations described above displayed by conventional wear-resistant steels that are used at present and do not provide a suitable balance between high hardness, hardenability, toughness and wear resistance in components with large thickness, typically up to 17 inches (43.18 cm).
The present invention overcomes these drawbacks with a method for producing steel that provides a cast steel of predominantly bainite structure with high hardness that is practically constant through the cross section in components with large thickness, which translates into high resistance to wear by abrasion and impact, maintaining a suitable balance between its hardness and toughness.
In one aspect, the present invention provides a method for producing cast steel having high wear resistance, with predominantly bainite microstructure and a suitable balance of toughness and hardness for grinding mining applications, crushing mining applications, or mining applications that require large components with high resistance to wear by abrasion and impact, wherein the chemical composition of steel used, expressed in percentage by weight, comprises at least:
- 0.30-0.40% w/w C;
- 0.50-1.30% w/w Si;
- 0.60-1.40% w/w Mn;
- 2.30-3.20% w/w Cr;
- 0.00-1.00% w/w Ni;
- 0.25-0.70% w/w Mo;
- 0.00-0.50% w/w Cu;
- 7a -- 0.00-0.10% w/w Al;
- 0.00-0.10% w/w Ti;
- 0.00-0.10% w/w Zr;
- less than 0.050% w/w P;
- less than 0.050% w/w S;
- less than 0.030% w/w N;
- the remainder is iron;
where the method comprises:
a) completely melting the steel having the aforementioned composition;
b) normalizing heat treatment at a temperature between 950 and 1050 C, for a time of between 3 and 10 hours; followed by cooling from the normalizing temperature to a temperature between 500 and 80 C, at a rate in the range from 0.05 to 0.5 C./s;
c) annealing heat treatment at a temperature in the range from 450 to 630 C, for a time of between 3 and 10 hours.
In another aspect, the present invention provides cast steel having high wear resistance, with predominantly bainite microstructure and a suitable balance of toughness and hardness for grinding mining applications, crushing mining applications, or mining applications that require large components with high resistance to wear by abrasion and impact, produced by the method as described herein.
One of the aims of the present invention is to provide a cast steel whose hardenability is sufficient to ensure high hardness over the entire cross section of components with large thickness or components of complex geometry with large changes of section, used in mining applications that require large components with high resistance to wear by abrasion and - 7b -impact, such as grinding and crushing, thus increasing the useful life of the components.
In another aspect, the present invention provides cast steel having high wear resistance and a suitable balance of toughness and hardness for grinding mining applications, crushing mining applications, or mining applications that require large components with high resistance to wear by abrasion and impact, comprising at least:
- 0.30-0.40% w/w C;
- 0.50-1.30% w/w Si;
- 0.60-1.40% w/w Mn;
- 2.30-3.20% w/w Cr;
- 0.00-1.00% w/w Ni;
- 0.25-0.70% w/w Mo;
- 0.00-0.50% w/w Cu;
- 0.00-0.10% w/w Al;
- 0.00-0.10% w/w Ti;
- 0.00-0.10% w/w Zr;
- less than 0.050% w/w P;
- less than 0.050% w/w S;
- less than 0.030% w/w N; and - the remainder is iron;
and in that said steel has a predominantly bainite structure.
Brief description of the figures For the purpose of describing the method of the present invention with greater clarity, a detailed description of the invention is provided below, with examples of application, which are illustrated in the accompanying figures, where:
Brief description of the invention The method and the steel of the present invention provide a solution to the limitations described above displayed by conventional wear-resistant steels that are used at present and do not provide a suitable balance between high hardness, hardenability, toughness and wear resistance in components with large thickness, typically up to 17 inches (43.18 cm).
The present invention overcomes these drawbacks with a method for producing steel that provides a cast steel of predominantly bainite structure with high hardness that is practically constant through the cross section in components with large thickness, which translates into high resistance to wear by abrasion and impact, maintaining a suitable balance between its hardness and toughness.
In one aspect, the present invention provides a method for producing cast steel having high wear resistance, with predominantly bainite microstructure and a suitable balance of toughness and hardness for grinding mining applications, crushing mining applications, or mining applications that require large components with high resistance to wear by abrasion and impact, wherein the chemical composition of steel used, expressed in percentage by weight, comprises at least:
- 0.30-0.40% w/w C;
- 0.50-1.30% w/w Si;
- 0.60-1.40% w/w Mn;
- 2.30-3.20% w/w Cr;
- 0.00-1.00% w/w Ni;
- 0.25-0.70% w/w Mo;
- 0.00-0.50% w/w Cu;
- 7a -- 0.00-0.10% w/w Al;
- 0.00-0.10% w/w Ti;
- 0.00-0.10% w/w Zr;
- less than 0.050% w/w P;
- less than 0.050% w/w S;
- less than 0.030% w/w N;
- the remainder is iron;
where the method comprises:
a) completely melting the steel having the aforementioned composition;
b) normalizing heat treatment at a temperature between 950 and 1050 C, for a time of between 3 and 10 hours; followed by cooling from the normalizing temperature to a temperature between 500 and 80 C, at a rate in the range from 0.05 to 0.5 C./s;
c) annealing heat treatment at a temperature in the range from 450 to 630 C, for a time of between 3 and 10 hours.
In another aspect, the present invention provides cast steel having high wear resistance, with predominantly bainite microstructure and a suitable balance of toughness and hardness for grinding mining applications, crushing mining applications, or mining applications that require large components with high resistance to wear by abrasion and impact, produced by the method as described herein.
One of the aims of the present invention is to provide a cast steel whose hardenability is sufficient to ensure high hardness over the entire cross section of components with large thickness or components of complex geometry with large changes of section, used in mining applications that require large components with high resistance to wear by abrasion and - 7b -impact, such as grinding and crushing, thus increasing the useful life of the components.
In another aspect, the present invention provides cast steel having high wear resistance and a suitable balance of toughness and hardness for grinding mining applications, crushing mining applications, or mining applications that require large components with high resistance to wear by abrasion and impact, comprising at least:
- 0.30-0.40% w/w C;
- 0.50-1.30% w/w Si;
- 0.60-1.40% w/w Mn;
- 2.30-3.20% w/w Cr;
- 0.00-1.00% w/w Ni;
- 0.25-0.70% w/w Mo;
- 0.00-0.50% w/w Cu;
- 0.00-0.10% w/w Al;
- 0.00-0.10% w/w Ti;
- 0.00-0.10% w/w Zr;
- less than 0.050% w/w P;
- less than 0.050% w/w S;
- less than 0.030% w/w N; and - the remainder is iron;
and in that said steel has a predominantly bainite structure.
Brief description of the figures For the purpose of describing the method of the present invention with greater clarity, a detailed description of the invention is provided below, with examples of application, which are illustrated in the accompanying figures, where:
- 8 -= Fig. 1 is a block diagram of an embodiment of the present invention, where the solid lines represent the main steps of the present invention.
= Fig. 2 illustrates the typical bainite microstructure of the steel obtained by the method of the present invention. Reagent Nital 5%, at 400X.
= Fig. 3 corresponds to a continuous cooling diagram (CCT, abbreviation for continuous cooling transformation) determined for one of the steels described in the present invention.
= Fig. 4 is a curve describing the kinetics of precipitation of particles of second phase of a GS-35 CrMoV 10 4 steel.
= Fig. 5 is a curve describing the kinetics of precipitation of particles of second phase of one of the steels described by the invention.
= Fig. 6 is the profile of Brinell hardness evaluated from the surface to the center of components made from a conventional pearlitic CrMo steel and a steel described by the invention.
= Fig. 7 is a graph showing the thermal cycle of normalizing and annealing according to a typical application of the present invention.
Detailed description of the invention One of the aims of the present invention is to provide a method for producing bainitic cast steel having high wear resisLance and exhibiting greater hardenability than the steels known in the prior art.
= Fig. 2 illustrates the typical bainite microstructure of the steel obtained by the method of the present invention. Reagent Nital 5%, at 400X.
= Fig. 3 corresponds to a continuous cooling diagram (CCT, abbreviation for continuous cooling transformation) determined for one of the steels described in the present invention.
= Fig. 4 is a curve describing the kinetics of precipitation of particles of second phase of a GS-35 CrMoV 10 4 steel.
= Fig. 5 is a curve describing the kinetics of precipitation of particles of second phase of one of the steels described by the invention.
= Fig. 6 is the profile of Brinell hardness evaluated from the surface to the center of components made from a conventional pearlitic CrMo steel and a steel described by the invention.
= Fig. 7 is a graph showing the thermal cycle of normalizing and annealing according to a typical application of the present invention.
Detailed description of the invention One of the aims of the present invention is to provide a method for producing bainitic cast steel having high wear resisLance and exhibiting greater hardenability than the steels known in the prior art.
- 9 -Another aim of the present invention is to provide a method for producing steel with high hardness over the entire cross section of components made therewith, especially those of large size.
Another aim of the present invention is to provide a bainitic cast steel having high wear resistance, with a suitable balance of toughness and hardness.
Yet another aim of the present invention is to provide a method for producing a cast steel with a suitable balance between chemical composition, toughness and hardenability; and a steel with said characteristics.
Another aim of the present invention is to provide large steel components for mining applications, such as crushing, grinding and all those applications that require large components with high resistance to wear by abrasion and impact, whose useful life is greater than that of components of the prior art; and a method for producing said steel.
The bainitic steel with increased toughness of the present invention has the following chemical composition:
= 0.30-0.40% w/w C
= 0.50-1.30% w/w Si = 0.60-1.40% w/w Mn = 2.30-3.20% w/w Cr, more preferably 2.40-3.0% w/w Cr = 0.0-1.00% w/w Ni = 0.25-0.70% w/w Mo = 0.0-0.50% w/w Cu = 0.0-0.10% w/w Al = 0.0-0.10% w/w Ti = 0.0-0.10% w/w Zr
Another aim of the present invention is to provide a bainitic cast steel having high wear resistance, with a suitable balance of toughness and hardness.
Yet another aim of the present invention is to provide a method for producing a cast steel with a suitable balance between chemical composition, toughness and hardenability; and a steel with said characteristics.
Another aim of the present invention is to provide large steel components for mining applications, such as crushing, grinding and all those applications that require large components with high resistance to wear by abrasion and impact, whose useful life is greater than that of components of the prior art; and a method for producing said steel.
The bainitic steel with increased toughness of the present invention has the following chemical composition:
= 0.30-0.40% w/w C
= 0.50-1.30% w/w Si = 0.60-1.40% w/w Mn = 2.30-3.20% w/w Cr, more preferably 2.40-3.0% w/w Cr = 0.0-1.00% w/w Ni = 0.25-0.70% w/w Mo = 0.0-0.50% w/w Cu = 0.0-0.10% w/w Al = 0.0-0.10% w/w Ti = 0.0-0.10% w/w Zr
- 10 -= Less than 0.050% w/w P
= Less than 0.050% w/w S
= Less than 0.030% w/w N
= Optionally less than 0.050% w/w Nb = Optionally 0.0005-0.005% w/w B
= Optionally 0.015-0.080% w/w rare earths = Residual contents of W, V, Sn, Sb, Pb and Zn less than 0.020% w/w and the balance iron.
Unless stated otherwise, the concept "Rare earths"
preferably refers herein to commercial mixtures of cerium and lanthanum.
Some of the basic criteria considered for limiting the chemical composition In the range described by the present invention were as follows:
= The carbon content is essential for determining the hardness of steel. Carbon contents under 0.30%
w/w are insufficient to obtain hardening by solid solution, high hardenability and hardening by precipitation of complex carbides or carbonitrides that guarantee practically constant hardness in large components and high wear resistance; whereas carbon contents above 0.40% w/w have an adverse effect on impact toughness in bainitic-martensitic steels.
= Silicon increases the strength of steel by solid solution hardening of the ferritic matrix of the bainite structures and delays the precipitation of carbides, so that it prevents abrupt decrease of hardness during annealing. However, silicon contents above 1.30% w/w have an adverse effect on the manufacture of components with large thickness, promoting the occurrence of phenomena of hot cracking.
= Manganese causes a moderate increase in hardenability of steel and refines bainite structures. However, at contents above 1.40% w/w it displays pronounced interdendritic chemical segregation, especially in large components.
= Chromium is an important element that provides strength, hardenability and hardening by precipitation of alloyed carbides of the M7C3 and M23C6 type. The inventors concluded that the range previously defined for chromium will produce a suitable balance of hardness, hardenability and distribution of chromium-rich alloyed carbides that ensure high wear resistance.
= Molybdenum is an important element that provides strength, high hardenability and hardening by precipitation of carbides of the M6C type and carbonitrides of the M(C,N) and M2(C,N) type.
Moreover, it greatly reduces the harmful effect of impurities that may segregate at grain boundaries, causing embrittlement. For this reason a minimum molybdenum content of 0.25% w/w is stipulated.
However, in view of its high cost, it is desirable to limit its content to a maximum of 0.70% w/w.
= Nickel increases the cohesion energy of the grain boundary, promotes the presence of bainite structures to the detriment of pearlite and has a synergistic effect on additions of manganese and molybdenum. However, it also has a high cost and its addition must be limited.
= Apart from having a deoxidizing effect, additions of titanium and zirconium allow nitrogen to be fixed in solid solution, control the grain size and provide hardening by precipitation of carbonitrides of the M(C,N) type. For its part, zirconium modifies the morphology of sulfide inclusions.
= Additions of rare earths, specifically mixtures of cerium and lanthanum, have an important effect on refinement of casting microstructure and on modification of the morphology of sulfide inclusions in steel.
Moreover, they increase resistance to surface fatigue.
= Additions of boron greatly increase hardenability and refine the acicular phases (bainite and martensite).
However, they may have an embrittlement effect when combined with nitrogen and form insoluble precipitates of BN at grain boundaries. Accordingly, the amount to be added and the sequence must be controlled in the ranges defined above.
= It has been found that the appropriate use of multicomponent master alloys that contain boron, titanium, zirconium, rare earths and particular mixtures thereof, together with controlled addition of these elements, ostensibly improves the properties of cast steels having high wear resistance for the mining applications described in this invention.
As illustrated in Figure 1, the method of production of the present invention provides a bainitic steel with the chemical composition detailed above that comprises the following steps:
- 12a -1. Melting: can be carried out by any conventional method.
For example, this operation can be performed in an arc furnace with basic or acidic refractory, or in an induction furnace.
Melting in an arc furnace, as a normal operation comprises complete melting of the charge, followed by blowing oxygen in, to produce oxidation of the liquid metal, transfer of impurities to the slag and decarburization of the metal to remove the nitrogen and hydrogen in solution. Then the operation of blocking of the liquid metal is carried out to stop oxidation, followed by the operation of refining and adjustment of the chemical composition to the specified range. Next, an operation of deoxidation is carried out using aluminum and master alloys of titanium and/or zirconium. Deoxidizing elements will be added in suitable amounts so that the residual contents of aluminum, titanium or zirconium are within the specified range for the alloy. If addition of boron and/or treatment with rare earths is required, this is performed in the ladle.
For its part, melting in an induction furnace as a normal operation comprises complete melting of the metal charge up to a temperature not above 1700 C, followed by adjustment of the chemical composition; followed by addition of master alloy of an element that is a strong nitride former -preferably titanium - to form a slag with a high capacity for nitrogen. Then the slag formed is removed and next the operation of deoxidation and discharge of the metal into a ladle is carried out.
2. Heat treatment: the normal operation of heat treatment applied to noncritical components comprises normalizing and annealing.
Normalizing is performed at a temperature in the range from 950 to 1050 C, for a holding time of between 3 and 10 hours depending on the characteristic thickness and geometry of the CA 02886286 2015-03-26 2014/022944 - 14 - ..
components to be produced. Then the components are submitted to a cooling step from the normalizing temperature to a temperature in the range from 500 to 80 C, more preferably between 500 and 150 C.
Cooling may be carried out either in still air or direct or indirect forced air, or a combination of both types of cooling, whenever the cooling rates of the center and surface of the component are within the range 0.050-0.50 C/s, so as to ensure optimal phase distribution.
Immediately following normalizing, an annealing heat treatment is carried out at a temperature in the range 450-630 C, for a time of between 3 and 10 hours depending on the geometry of the component and the range of hardness that is to be reached. The annealing heat treatment has the aim of achieving maximum possible transformation of the austenite, annealing the acicular phases formed and producing secondary hardening by precipitation of alloyed carbides predominantly rich in molybdenum.
As has been mentioned, the cast steel of predominantly bainite structure (like that shown in Fig. 2) that is obtained by the method of the present invention, and that comprises the chemical composition detailed above, has a number of advantages over other steels of the prior art. One of these advantages is the high hardness of the steel obtained, which is attained, among other factors, owing to the absence of phenomena of enlargement and coalescence of precipitates during a normal annealing cycle, as shown in Fig. 5.
In contrast, it can be seen from Fig. 4 that the steels of the prior art, such as CrMoV, usually exhibit an abrupt decrease in hardness, which could promote the occurrence of phenomena of embritt1ement during annealing. In particular, this figure illustrates the kinetics of precipitation of particles of second phase of a GS-35 CrMoV 10 4 steel, according to standard DIN
17205, which specifies hardened and annealed cast steels for general applications. Although this steel has a chemical composition somewhat similar to that of the present invention, it displays rapid enlargement and coalescence of cementite and carbonitrides of the M2(C,N) type, affecting its hardness.
Another advantage of the present invention is that the increased hardness is constant through the cross section of a component of large thickness, which is not achieved with steels of the prior art, as can be seen in Fig. 6.
In accordance with the foregoing, the cast steel obtained by the method of the present invention exhibits a suitable balance of chemical composition, toughness and hardenability to ensure complete hardening in castings of large size, typically up to 17 inches (43.18 cm) in thickness, with Brinell hardness preferably in the range 385-495 BHN throughout the cross section of the component and excellent resistance to wear by abrasion and impact.
Embodiment examples Various tests of the method of the present invention were carried out, using chemical compositions within the ranges that are disclosed here.
In the following, a conventional Cr-Mo pearlitic steel, widely used in coatings for SAG mills, is compared against five examples of steels obtained by the method of the present invention.
The tests were performed in the operating conditions presented in Tables 1 and 2. Table 3 shows the chemical compositions used in each case, expressed in % w/w.
Finally, Table 4 shows the phase distribution and hardnesses obtained in the heat treatment conditions applied, whose cooling rate corresponds to that typically encountered in components of large thickness.
Fig. 7 shows a diagram of the thermal cycle used in this example, where segment (a) describes the step of heating the components to the normalizing temperature.
Segment (b) shows a holding time at the normalizing temperature for 4 hours. For its part, segment (c) represents the step of cooling in air from normalizing to a temperature of 200 C, at an average cooling rate as indicated in Table 2. Segment (e) shows a holding time at the annealing temperature of 5 hours.
,, g;
r8 Table 1: Operational data of the step of melting and casting Parameter CrMo pearlitic Example 1, Example 2, Example 3, Example 4, Example 5, steel Invention Invention Invention Invention Invention Type of melting induction induction induction arc furnace arc furnace arc furnace furnace furnace furnace furnace Casting temperature Table 2: Operational data of the thermal cycle applied _______________________________________________________________________________ ___________________________________ CrMo pearlitic Example 1, Example 2, Example 3, Example 4, Example 5, Parameter steel Invention Invention Invention Invention Invention Normalizing temperature 950 C 970 C 970 C
_ Holding time 4 h 4 h 4 h 4 h 4 h 4 h Average cooling rate 0.10 C/s 0.10 C/s 0.10 C/s 0.10 C/s 0.10 C/s 0.10 C/s _ Annealing temperature 570 C 570 C 570 C
_ _______________________________________________________________________________ ___________________________________________ Annealing time 5 h 5 h 5 h 5 h 5 h 5 h m m m to m m N, . Table 3: Chemical composition of steels expressed in % w/w N, m CrMo pearlitic Example 1, Example 2, Example 3, Example 4, Example 5, Element steel Invention Invention Invention Invention Invention C 0.60 0.36 0.35 0.38 0.34 0.33 Si 0.70 0.90 1.0 0.80 1.0 1.0 Mn 0.90 1.20 0.85 1.10 1.30 1.20 Cr 2.20 2.70 2.50 2.80 2.60 3.0 Ni 0.0 0.40 0.30 0.30 0.0 0.30 Mo 0.40 0.50 0.45 0.55 0.40 0.45 Cu 0.10 0.0 0.10 0.10 0.0 0.0 Al 0.035 0.02 0.015 0.015 0.020 0.015 __ Ti 0.0 0.030 0.020 0.020 0.030 0.0 Zr 0.02 0.010 0.025 0.020 0.015 0.035 Nb 0.0 0.0 0.0 0.020 0.015 0.020 N 0.011 0.010 0.012 0.013 0.010 0.012 B 0.0 0.0 0.0010 0.0010 0.0010 0.0 to r8 Table 4: Microstructure and Brinell hardness developed by the method of the present invention Resultant microstructure Alloy Brinell hardness % pearlite % bainite % martensite CrMo pearlitic steel 67.6 32.4 Example 1, Invention 3.60 83.20 13.70 476 Example 2, Invention 5.60 86.60 5.70 466 Example 3, Invention 3.10 77.40 19.20 491 Example 4, Invention 3.0 67.60 29.10 468 Example 5, Invention 4.2 84.5
= Less than 0.050% w/w S
= Less than 0.030% w/w N
= Optionally less than 0.050% w/w Nb = Optionally 0.0005-0.005% w/w B
= Optionally 0.015-0.080% w/w rare earths = Residual contents of W, V, Sn, Sb, Pb and Zn less than 0.020% w/w and the balance iron.
Unless stated otherwise, the concept "Rare earths"
preferably refers herein to commercial mixtures of cerium and lanthanum.
Some of the basic criteria considered for limiting the chemical composition In the range described by the present invention were as follows:
= The carbon content is essential for determining the hardness of steel. Carbon contents under 0.30%
w/w are insufficient to obtain hardening by solid solution, high hardenability and hardening by precipitation of complex carbides or carbonitrides that guarantee practically constant hardness in large components and high wear resistance; whereas carbon contents above 0.40% w/w have an adverse effect on impact toughness in bainitic-martensitic steels.
= Silicon increases the strength of steel by solid solution hardening of the ferritic matrix of the bainite structures and delays the precipitation of carbides, so that it prevents abrupt decrease of hardness during annealing. However, silicon contents above 1.30% w/w have an adverse effect on the manufacture of components with large thickness, promoting the occurrence of phenomena of hot cracking.
= Manganese causes a moderate increase in hardenability of steel and refines bainite structures. However, at contents above 1.40% w/w it displays pronounced interdendritic chemical segregation, especially in large components.
= Chromium is an important element that provides strength, hardenability and hardening by precipitation of alloyed carbides of the M7C3 and M23C6 type. The inventors concluded that the range previously defined for chromium will produce a suitable balance of hardness, hardenability and distribution of chromium-rich alloyed carbides that ensure high wear resistance.
= Molybdenum is an important element that provides strength, high hardenability and hardening by precipitation of carbides of the M6C type and carbonitrides of the M(C,N) and M2(C,N) type.
Moreover, it greatly reduces the harmful effect of impurities that may segregate at grain boundaries, causing embrittlement. For this reason a minimum molybdenum content of 0.25% w/w is stipulated.
However, in view of its high cost, it is desirable to limit its content to a maximum of 0.70% w/w.
= Nickel increases the cohesion energy of the grain boundary, promotes the presence of bainite structures to the detriment of pearlite and has a synergistic effect on additions of manganese and molybdenum. However, it also has a high cost and its addition must be limited.
= Apart from having a deoxidizing effect, additions of titanium and zirconium allow nitrogen to be fixed in solid solution, control the grain size and provide hardening by precipitation of carbonitrides of the M(C,N) type. For its part, zirconium modifies the morphology of sulfide inclusions.
= Additions of rare earths, specifically mixtures of cerium and lanthanum, have an important effect on refinement of casting microstructure and on modification of the morphology of sulfide inclusions in steel.
Moreover, they increase resistance to surface fatigue.
= Additions of boron greatly increase hardenability and refine the acicular phases (bainite and martensite).
However, they may have an embrittlement effect when combined with nitrogen and form insoluble precipitates of BN at grain boundaries. Accordingly, the amount to be added and the sequence must be controlled in the ranges defined above.
= It has been found that the appropriate use of multicomponent master alloys that contain boron, titanium, zirconium, rare earths and particular mixtures thereof, together with controlled addition of these elements, ostensibly improves the properties of cast steels having high wear resistance for the mining applications described in this invention.
As illustrated in Figure 1, the method of production of the present invention provides a bainitic steel with the chemical composition detailed above that comprises the following steps:
- 12a -1. Melting: can be carried out by any conventional method.
For example, this operation can be performed in an arc furnace with basic or acidic refractory, or in an induction furnace.
Melting in an arc furnace, as a normal operation comprises complete melting of the charge, followed by blowing oxygen in, to produce oxidation of the liquid metal, transfer of impurities to the slag and decarburization of the metal to remove the nitrogen and hydrogen in solution. Then the operation of blocking of the liquid metal is carried out to stop oxidation, followed by the operation of refining and adjustment of the chemical composition to the specified range. Next, an operation of deoxidation is carried out using aluminum and master alloys of titanium and/or zirconium. Deoxidizing elements will be added in suitable amounts so that the residual contents of aluminum, titanium or zirconium are within the specified range for the alloy. If addition of boron and/or treatment with rare earths is required, this is performed in the ladle.
For its part, melting in an induction furnace as a normal operation comprises complete melting of the metal charge up to a temperature not above 1700 C, followed by adjustment of the chemical composition; followed by addition of master alloy of an element that is a strong nitride former -preferably titanium - to form a slag with a high capacity for nitrogen. Then the slag formed is removed and next the operation of deoxidation and discharge of the metal into a ladle is carried out.
2. Heat treatment: the normal operation of heat treatment applied to noncritical components comprises normalizing and annealing.
Normalizing is performed at a temperature in the range from 950 to 1050 C, for a holding time of between 3 and 10 hours depending on the characteristic thickness and geometry of the CA 02886286 2015-03-26 2014/022944 - 14 - ..
components to be produced. Then the components are submitted to a cooling step from the normalizing temperature to a temperature in the range from 500 to 80 C, more preferably between 500 and 150 C.
Cooling may be carried out either in still air or direct or indirect forced air, or a combination of both types of cooling, whenever the cooling rates of the center and surface of the component are within the range 0.050-0.50 C/s, so as to ensure optimal phase distribution.
Immediately following normalizing, an annealing heat treatment is carried out at a temperature in the range 450-630 C, for a time of between 3 and 10 hours depending on the geometry of the component and the range of hardness that is to be reached. The annealing heat treatment has the aim of achieving maximum possible transformation of the austenite, annealing the acicular phases formed and producing secondary hardening by precipitation of alloyed carbides predominantly rich in molybdenum.
As has been mentioned, the cast steel of predominantly bainite structure (like that shown in Fig. 2) that is obtained by the method of the present invention, and that comprises the chemical composition detailed above, has a number of advantages over other steels of the prior art. One of these advantages is the high hardness of the steel obtained, which is attained, among other factors, owing to the absence of phenomena of enlargement and coalescence of precipitates during a normal annealing cycle, as shown in Fig. 5.
In contrast, it can be seen from Fig. 4 that the steels of the prior art, such as CrMoV, usually exhibit an abrupt decrease in hardness, which could promote the occurrence of phenomena of embritt1ement during annealing. In particular, this figure illustrates the kinetics of precipitation of particles of second phase of a GS-35 CrMoV 10 4 steel, according to standard DIN
17205, which specifies hardened and annealed cast steels for general applications. Although this steel has a chemical composition somewhat similar to that of the present invention, it displays rapid enlargement and coalescence of cementite and carbonitrides of the M2(C,N) type, affecting its hardness.
Another advantage of the present invention is that the increased hardness is constant through the cross section of a component of large thickness, which is not achieved with steels of the prior art, as can be seen in Fig. 6.
In accordance with the foregoing, the cast steel obtained by the method of the present invention exhibits a suitable balance of chemical composition, toughness and hardenability to ensure complete hardening in castings of large size, typically up to 17 inches (43.18 cm) in thickness, with Brinell hardness preferably in the range 385-495 BHN throughout the cross section of the component and excellent resistance to wear by abrasion and impact.
Embodiment examples Various tests of the method of the present invention were carried out, using chemical compositions within the ranges that are disclosed here.
In the following, a conventional Cr-Mo pearlitic steel, widely used in coatings for SAG mills, is compared against five examples of steels obtained by the method of the present invention.
The tests were performed in the operating conditions presented in Tables 1 and 2. Table 3 shows the chemical compositions used in each case, expressed in % w/w.
Finally, Table 4 shows the phase distribution and hardnesses obtained in the heat treatment conditions applied, whose cooling rate corresponds to that typically encountered in components of large thickness.
Fig. 7 shows a diagram of the thermal cycle used in this example, where segment (a) describes the step of heating the components to the normalizing temperature.
Segment (b) shows a holding time at the normalizing temperature for 4 hours. For its part, segment (c) represents the step of cooling in air from normalizing to a temperature of 200 C, at an average cooling rate as indicated in Table 2. Segment (e) shows a holding time at the annealing temperature of 5 hours.
,, g;
r8 Table 1: Operational data of the step of melting and casting Parameter CrMo pearlitic Example 1, Example 2, Example 3, Example 4, Example 5, steel Invention Invention Invention Invention Invention Type of melting induction induction induction arc furnace arc furnace arc furnace furnace furnace furnace furnace Casting temperature Table 2: Operational data of the thermal cycle applied _______________________________________________________________________________ ___________________________________ CrMo pearlitic Example 1, Example 2, Example 3, Example 4, Example 5, Parameter steel Invention Invention Invention Invention Invention Normalizing temperature 950 C 970 C 970 C
_ Holding time 4 h 4 h 4 h 4 h 4 h 4 h Average cooling rate 0.10 C/s 0.10 C/s 0.10 C/s 0.10 C/s 0.10 C/s 0.10 C/s _ Annealing temperature 570 C 570 C 570 C
_ _______________________________________________________________________________ ___________________________________________ Annealing time 5 h 5 h 5 h 5 h 5 h 5 h m m m to m m N, . Table 3: Chemical composition of steels expressed in % w/w N, m CrMo pearlitic Example 1, Example 2, Example 3, Example 4, Example 5, Element steel Invention Invention Invention Invention Invention C 0.60 0.36 0.35 0.38 0.34 0.33 Si 0.70 0.90 1.0 0.80 1.0 1.0 Mn 0.90 1.20 0.85 1.10 1.30 1.20 Cr 2.20 2.70 2.50 2.80 2.60 3.0 Ni 0.0 0.40 0.30 0.30 0.0 0.30 Mo 0.40 0.50 0.45 0.55 0.40 0.45 Cu 0.10 0.0 0.10 0.10 0.0 0.0 Al 0.035 0.02 0.015 0.015 0.020 0.015 __ Ti 0.0 0.030 0.020 0.020 0.030 0.0 Zr 0.02 0.010 0.025 0.020 0.015 0.035 Nb 0.0 0.0 0.0 0.020 0.015 0.020 N 0.011 0.010 0.012 0.013 0.010 0.012 B 0.0 0.0 0.0010 0.0010 0.0010 0.0 to r8 Table 4: Microstructure and Brinell hardness developed by the method of the present invention Resultant microstructure Alloy Brinell hardness % pearlite % bainite % martensite CrMo pearlitic steel 67.6 32.4 Example 1, Invention 3.60 83.20 13.70 476 Example 2, Invention 5.60 86.60 5.70 466 Example 3, Invention 3.10 77.40 19.20 491 Example 4, Invention 3.0 67.60 29.10 468 Example 5, Invention 4.2 84.5
11.2 468 As can be seen, in all cases the method of the present invention provides a cast steel with predominantly bainite structure and with higher Brinell hardness.
As can be seen in Fig. 6, the profile of Brinell hardness evaluated from the surface of the component toward its interior, to a depth of 13 inches (33.0 cm), remains practically constant. In contrast, the Cr-Mo pearlitic steel shows a considerable decrease in hardness through its cross section.
The foregoing description deals with the aims and advantages of the present invention. It must be understood that various embodiments of this invention may be implemented and that all the subject matter disclosed here must be interpreted as being for purposes of illustration and is not limiting in any way.
As can be seen in Fig. 6, the profile of Brinell hardness evaluated from the surface of the component toward its interior, to a depth of 13 inches (33.0 cm), remains practically constant. In contrast, the Cr-Mo pearlitic steel shows a considerable decrease in hardness through its cross section.
The foregoing description deals with the aims and advantages of the present invention. It must be understood that various embodiments of this invention may be implemented and that all the subject matter disclosed here must be interpreted as being for purposes of illustration and is not limiting in any way.
Claims (23)
1. A method for producing cast steel having high wear resistance, with predominantly bainite microstructure and a suitable balance of toughness and hardness for grinding mining applications, crushing mining applications, or mining applications that require large components with high resistance to wear by abrasion and impact, wherein the chemical composition of steel used, expressed in percentage by weight, comprises at least:
- 0.30-0.40% w/w C;
- 0.50-1.30% w/w Si;
- 0.60-1.40% w/w Mn;
- 2.30-3.20% w/w Cr;
- 0.00-1.00% w/w Ni;
- 0.25-0.70% w/w Mo;
- 0.00-0.50% w/w Cu;
- 0.00-0.10% w/w Al;
- 0.00-0.10% w/w Ti;
- 0.00-0.10% w/w Zr;
- less than 0.050% w/w P;
- less than 0.050% w/w S;
- less than 0.030% w/w N;
- the remainder is iron;
where the method comprises:
a) completely melting the steel having the aforementioned composition;
b) normalizing heat treatment at a temperature between 950 and 1050° C, for a time of between 3 and 10 hours; followed by cooling from the normalizing temperature to a temperature between 500 and 80° C, at a rate in the range from 0.05 to 0.5° C./s;
c) annealing heat treatment at a temperature in the range from 450 to 630° C, for a time of between 3 and 10 hours.
- 0.30-0.40% w/w C;
- 0.50-1.30% w/w Si;
- 0.60-1.40% w/w Mn;
- 2.30-3.20% w/w Cr;
- 0.00-1.00% w/w Ni;
- 0.25-0.70% w/w Mo;
- 0.00-0.50% w/w Cu;
- 0.00-0.10% w/w Al;
- 0.00-0.10% w/w Ti;
- 0.00-0.10% w/w Zr;
- less than 0.050% w/w P;
- less than 0.050% w/w S;
- less than 0.030% w/w N;
- the remainder is iron;
where the method comprises:
a) completely melting the steel having the aforementioned composition;
b) normalizing heat treatment at a temperature between 950 and 1050° C, for a time of between 3 and 10 hours; followed by cooling from the normalizing temperature to a temperature between 500 and 80° C, at a rate in the range from 0.05 to 0.5° C./s;
c) annealing heat treatment at a temperature in the range from 450 to 630° C, for a time of between 3 and 10 hours.
2. The method as claimed in claim 1, wherein the percentage by weight of chromium in the chemical composition of the steel is 2.40-3.00% w/w.
3. The method as claimed in claim 1 or 2, wherein the chemical composition of the steel further comprises less than 0.050% w/w of niobium.
4. The method as claimed in any one of claims 1 to 3, wherein the chemical composition of the steel further comprises boron in the range 0.0005-0.005% w/w.
5. The method as claimed in any one of claims 1 to 4, wherein the chemical composition of the steel further comprises rare earths in the range 0.015-0.080% w/w.
6. The method as claimed in claim 5, wherein the rare earths correspond to commercial mixtures of cerium and lanthanum.
7. The method as claimed in any one of claims 1 to 6, wherein the chemical composition of the steel further comprises residual contents of tungsten, vanadium, tin, antimony, lead and zinc of less than 0.020% w/w.
8. The method as claimed in any one of claims 1 to 7, wherein the melting step (a) is carried out in an arc furnace.
9. The method as claimed in claim 8, wherein the arc furnace has a basic refractory or an acid refractory.
10. The method as claimed in any one of claims 1 to 7, wherein the melting step (a) is carried out in an induction furnace.
11. The method as claimed in claim 10, wherein the melting step (a) is carried out at a maximum temperature of 1700°C.
12. The method as claimed in any one of claims 1 to 11, wherein the cooling in the normalizing heat treatment step (b) is carried out until a temperature of between 500 and 150°C is reached.
13. The method as claimed in any one of claims 1 to 12, wherein the cooling in the normalizing heat treatment step (b) is carried out in still air.
14. The method as claimed in any one of claims 1 to 12, wherein the cooling in the normalizing heat treatment step (b) is carried out in direct or indirect forced air.
15. The method as claimed in any one of claims 1 to 12, wherein the cooling in the normalizing heat treatment step (b) is carried out by a sequence of substeps in still air and in indirect forced air.
16. Cast steel having high wear resistance, with predominantly bainite microstructure and a suitable balance of toughness and hardness for grinding mining applications, crushing mining applications, or mining applications that require large components with high resistance to wear by abrasion and impact, produced by the method as claimed in any one of claims 1 to 15.
17. Cast steel having high wear resistance and a suitable balance of toughness and hardness for grinding mining applications, crushing mining applications, or mining applications that require large components with high resistance to wear by abrasion and impact, comprising at least:
- 0.30-0.40% w/w C;
- 0.50-1.30% w/w Si;
- 0.60-1.40% w/w Mn;
- 2.30-3.20% w/w Cr;
- 0.00-1.00% w/w Ni;
- 0.25-0.70% w/w Mo;
- 0.00-0.50% w/w Cu;
- 0.00-0.10% w/w Al;
- 0.00-0.10% w/w Ti;
- 0.00-0.10% w/w Zr;
- less than 0.050% w/w P;
- less than 0.050% w/w S;
- less than 0.030% w/w N; and - the remainder is iron;
and in that said steel has a predominantly bainite structure.
- 0.30-0.40% w/w C;
- 0.50-1.30% w/w Si;
- 0.60-1.40% w/w Mn;
- 2.30-3.20% w/w Cr;
- 0.00-1.00% w/w Ni;
- 0.25-0.70% w/w Mo;
- 0.00-0.50% w/w Cu;
- 0.00-0.10% w/w Al;
- 0.00-0.10% w/w Ti;
- 0.00-0.10% w/w Zr;
- less than 0.050% w/w P;
- less than 0.050% w/w S;
- less than 0.030% w/w N; and - the remainder is iron;
and in that said steel has a predominantly bainite structure.
18. The cast steel as claimed in claim 17, wherein the percentage by weight of chromium in the chemical composition of the steel is 2.40-3.00% w/w.
19. The cast steel as claimed in claim 17 or 18, wherein the chemical composition of the steel further comprises less than 0.050% w/w of niobium.
20. The cast steel as claimed in any one of claims 17 to 19, wherein the chemical composition of the steel further comprises boron in the range 0.0005-0.005% w/w.
21. The cast steel as claimed in any one of claims 17 to 20, wherein the chemical composition of the steel further comprises rare earths in the range 0.015-0.080% w/w.
22. The cast steel as claimed in claim 21, wherein the rare earths correspond to commercial mixtures of cerium and lanthanum.
23. The cast steel as claimed in any one of claims 17 to 22, wherein the chemical composition of the steel further comprises residual contents of tungsten, vanadium, tin, antimony, lead and zinc of less than 0.020% w/w.
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| CL2218-2012 | 2012-08-09 | ||
| CL2012002218A CL2012002218A1 (en) | 2012-08-09 | 2012-08-09 | Production method of high wear resistance cast steel with mostly bainitic microstructure and adequate balance of toughness and hardness for mining applications such as grinding and crushing; and steel with these characteristics. |
| PCT/CL2013/000047 WO2014022944A1 (en) | 2012-08-09 | 2013-07-25 | Method for producing molten steel having high wear resistance and steel having said characteristics |
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| CN105861957A (en) * | 2016-06-02 | 2016-08-17 | 芜湖三刀材料科技有限公司 | High-strength high-wear resistance alloy steel and preparation method thereof |
| JP6607209B2 (en) * | 2017-02-03 | 2019-11-20 | Ｊｆｅスチール株式会社 | Abrasion resistant steel sheet and method for producing the abrasion resistant steel sheet |
| CN108728753A (en) * | 2018-05-30 | 2018-11-02 | 无锡市诚天诺执行器制造有限公司 | A kind of pneumatic actuator output shaft material and preparation method thereof |
| CN110484824A (en) * | 2019-09-23 | 2019-11-22 | 益阳金能新材料有限责任公司 | A kind of wear-resisting alloy steel and preparation method thereof |
| CN112522621A (en) * | 2020-11-30 | 2021-03-19 | 自贡硬质合金有限责任公司 | Composite wear-resistant metal block and preparation method thereof |
| CN113637898B (en) * | 2021-07-16 | 2022-05-20 | 安徽瑞泰新材料科技有限公司 | High-hardness high-toughness wear-resistant ball and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1450355A (en) * | 1920-06-01 | 1923-04-03 | Cohen Myer | Coin-controlled lock |
| IT957295B (en) * | 1972-03-02 | 1973-10-10 | Italsider Spa | PERFECTED PROCESS FOR THE REALIZATION OF STEEL MONOBLOCK WHEELS |
| DE2302865C2 (en) * | 1973-01-20 | 1975-09-11 | Fried. Krupp Huettenwerke Ag, 4630 Bochum | Method for producing an uncoated high-strength rail |
| US5759299A (en) * | 1994-05-10 | 1998-06-02 | Nkk Corporation | Rail having excellent resistance to rolling fatigue damage and rail having excellent toughness and wear resistance and method of manufacturing the same |
| GB2297094B (en) * | 1995-01-20 | 1998-09-23 | British Steel Plc | Improvements in and relating to Carbide-Free Bainitic Steels |
| FR2847274B1 (en) * | 2002-11-19 | 2005-08-19 | Usinor | SOLDERABLE CONSTRUCTION STEEL PIECE AND METHOD OF MANUFACTURE |
| CN1328406C (en) * | 2005-06-22 | 2007-07-25 | 宁波浙东精密铸造有限公司 | Martensite wear resistant cast steel with film austenic toughened and its manufacturing method |
-
2012
- 2012-08-09 CL CL2012002218A patent/CL2012002218A1/en unknown
-
2013
- 2013-07-25 WO PCT/CL2013/000047 patent/WO2014022944A1/en active Application Filing
- 2013-07-25 CA CA2886286A patent/CA2886286C/en active Active
- 2013-07-25 AU AU2013302197A patent/AU2013302197B2/en active Active
- 2013-07-25 PE PE2015000177A patent/PE20150740A1/en active IP Right Grant
- 2013-07-25 CN CN201380051953.4A patent/CN104822847B/en active Active
- 2013-07-25 US US14/420,586 patent/US20150252457A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| US20150252457A1 (en) | 2015-09-10 |
| CN104822847A (en) | 2015-08-05 |
| AU2013302197A1 (en) | 2015-03-26 |
| WO2014022944A1 (en) | 2014-02-13 |
| CN104822847B (en) | 2018-11-09 |
| CL2012002218A1 (en) | 2013-07-26 |
| PE20150740A1 (en) | 2015-05-17 |
| CA2886286A1 (en) | 2014-02-13 |
| AU2013302197B2 (en) | 2018-01-25 |
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| EEER | Examination request |
Effective date: 20180529 |