WO2009061073A1 - High tensile steel for deep drawing and manufacturing method thereof - Google Patents
High tensile steel for deep drawing and manufacturing method thereof Download PDFInfo
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- WO2009061073A1 WO2009061073A1 PCT/KR2008/005432 KR2008005432W WO2009061073A1 WO 2009061073 A1 WO2009061073 A1 WO 2009061073A1 KR 2008005432 W KR2008005432 W KR 2008005432W WO 2009061073 A1 WO2009061073 A1 WO 2009061073A1
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- Prior art keywords
- steel
- less
- deep drawing
- heat treatment
- temperature
- Prior art date
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 131
- 239000010959 steel Substances 0.000 title claims abstract description 131
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 27
- 238000010438 heat treatment Methods 0.000 claims abstract description 42
- 238000000034 method Methods 0.000 claims abstract description 30
- 229910001563 bainite Inorganic materials 0.000 claims abstract description 12
- 229910000734 martensite Inorganic materials 0.000 claims abstract description 12
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 10
- 229910052796 boron Inorganic materials 0.000 claims abstract description 8
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 8
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 6
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 6
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 6
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 6
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 6
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 6
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 6
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 5
- 239000012535 impurity Substances 0.000 claims abstract description 5
- 238000005096 rolling process Methods 0.000 claims description 13
- 238000005496 tempering Methods 0.000 claims description 8
- 238000010791 quenching Methods 0.000 claims description 6
- 230000000171 quenching effect Effects 0.000 claims description 6
- 230000008569 process Effects 0.000 abstract description 16
- 230000006866 deterioration Effects 0.000 abstract description 6
- 239000010936 titanium Substances 0.000 description 9
- 239000011651 chromium Substances 0.000 description 8
- 239000011575 calcium Substances 0.000 description 7
- 238000005261 decarburization Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 239000011572 manganese Substances 0.000 description 7
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 7
- 230000000704 physical effect Effects 0.000 description 7
- 230000002411 adverse Effects 0.000 description 4
- 238000005275 alloying Methods 0.000 description 4
- 229910001566 austenite Inorganic materials 0.000 description 4
- 239000006104 solid solution Substances 0.000 description 4
- 238000009628 steelmaking Methods 0.000 description 4
- 239000013078 crystal Substances 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910001562 pearlite Inorganic materials 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 230000009466 transformation Effects 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
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-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
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 230000003389 potentiating effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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- 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
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/32—Soft annealing, e.g. spheroidising
-
- 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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
- C21D8/0426—Hot rolling
-
- 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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
- C21D8/0447—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the heat treatment
-
- 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
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
- C21D9/48—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals deep-drawing sheets
-
- 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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
-
- 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
- C22C38/22—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
- C22C38/28—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
- C22C38/40—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
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel 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
- C22C38/40—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
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
-
- 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
- C21D2211/008—Martensite
Definitions
- the present invention relates to a steel for deep drawing that has a tensile strength of approximately 1200 MPa and is used for a low-temperature, high-pressure container, and a manufacturing method thereof, and more particularly, to a high-tensile strength steel for a low-temperature, high-pressure container, which secures low temperature toughness in the manufacture of the steel for a low-temperature, high-pressure container, a CNG storage container for automobiles and the like, reduces a drop of strength by decarburization by curtailing a required spheroidization heat treatment of steel, and shows its excellent economical efficiency and productivity, and a manufacturing method thereof.
- a method of manufacturing a cylinder for a pressure container has been used in the prior art, which include: subjecting a seamless pipe to a spinning-type process.
- the cylinder prepared by the spinning-type process has problems in that the cylinder has a bad appearance due to the presence of seams in the cylinder, and its physical properties in the seamed portions may be deteriorated.
- V vanadium
- carbide precipitation is often included in the steel after a quenching-tempering process. Therefore, when the steel is subject to a spheroidization heat treatment prior to the deep drawing process, the strength of steel is excessively enhanced by the V precipitation strengthening, which makes it difficult to directly use the steel in the deep drawing process.
- the spheroidization heat treatment may be performed prior to the deep drawing process in order to give suitable workability to the steel.
- the spheroidization heat treatment is carried out for a long time (i.e. at least 90 minutes). Therefore, the spheroidization heat treatment has problems in terms of its low steel productivity and high manufacturing cost, and the strength of steel may also be deteriorated due to the decarburization caused by the long-time spheroidization heat treatment.
- the present invention is designed to solve the problems of the prior art, and therefore it is an object of the present invention to provide a steel having an excellent low- temperature toughness and a tensile strength of approximately 1200 MPa, which is able to save the manufacturing time and cost by curtailing a time for the long-term spheroidization heat treatment, suppress the deterioration in the strength of steel caused by the decarburization, and give high workability to the steel by maintaining the strength of steel to 700 MPa or less after the spheroidization heat treatment.
- a steel for deep drawing including, by weight: C: 0.25 to 0.40%, Si: 0.15 to 0.40%, Mn: 0.4 to 1.0%, Al: 0.001 to 0.05%, Cr: 0.8 to 1.2%, Mo: 0.15 to 0.8%, Ni: 1.0% or less, P: 0.015% or less, S: 0.015% or less, Ca: 0.0005 to 0.002%, Ti: 0.005 to 0.025%, B: 0.0005 to 0.0020% and the balance of Fe and inevitable impurities, wherein a microstructure of the steel for deep drawing has a triphase structure of ferrite, bainite and martensite.
- a method for manufacturing a steel for deep drawing wherein the steel for deep drawing has a tensile strength of approximately 1200 MPa and a low-temperature impact toughness (at -5O 0 C) of 37 Joules or more, and also a method for manufacturing a high-pressure container made of the steel.
- the method includes: heating a steel ingot at 1000 to 125O 0 C, the steel comprising, by weight: C: 0.25 to 0.40%, Si: 0.15 to 0.40%, Mn: 0.4 to 1.0%, Al: 0.001 to 0.05%, Cr: 0.8 to 1.2%, Mo: 0.15 to 0.8%, Ni: 1.0% or less, P: 0.015% or less, S: 0.015% or less, Ca: 0.0005 to 0.002%, Ti: 0.005 to 0.025%, B: 0.0005 to 0.0020% and the balance of Fe and inevitable impurities (re-heating operation); rolling the re-heated steel ingot at a rolling finish temperature of 750 to 1000 0 C (rolling operation); normalizing the rolled steel so that a microstructure of the steel is formed into a triphase structure of ferrite, bainite and martensite (normalizing operation); manufacturing a high-pressure container by subjecting the normalized steel to a spheroidization heat treatment at a temperature of Ac to Ac
- the steel according to one exemplary embodiment of the present invention may be useful to further improve the strength without the deterioration of the toughness by adding a trace of Ti and B, compared to the conventional steels having a strength of approximately 1100 MPa.
- the method for manufacturing a steel according to one exemplary embodiment of the present invention may be useful to save the manufacturing cost and time by significantly curtailing a time for the spheroidization heat treatment during the deep drawing process, and to manufacture a steel for deep drawing that is used for a low-temperature, high-pressure container having a tensile strength of approximately 1200 MPa by reducing a depth of the softening layer to prevent the deterioration in strength of the steel.
- the exemplary embodiment of the present invention may provide a steel having a tensile strength of approximately 1200 MPa, and a suitable heat treatment method by means of an alloy design that is suitable for a deep drawing process. Therefore, there is provided a steel for a low-temperature, high-pressure container that has a smooth appearance, is seamless, and shows its excellent physical properties and productivity.
- Carbon (C) is an element that is added to secure a desired strength of steel.
- the content of added C is too small, the strength of steel may be deteriorated severely, whereas weldability of steel may be deteriorated when the content of added C is too high. Therefore, the added C is used at a limited content of 0.25 to 0.40%.
- Si functions as a deoxidizing agent that is required for a steel-making process, and also as a solid solution hardening element that affects the strength of steel. Therefore, Si is added in a content range of 0.15 to 0.40%.
- Manganese (Mn) is an alloying element that has a significant effect on the strength and toughness of steel.
- Mn is an alloying element that has a significant effect on the strength and toughness of steel.
- Mn is used at a limited content of 0.4 to 1.0%.
- Al is one of potent deoxidizing agents used in a steel-making process.
- content of added Al does not exceed 0.001%, its addition effect is slight.
- content of added Al exceeds 0.05%, its addition effect is not further improved. Therefore, Al is added within a content range of 0.001 to 0.05%.
- Chromium (Cr) is an essential alloying element that is used to give hardenability to steel.
- Cr is added at a content of 0.8 to 1.2%.
- the content of Cr is less than 0.8%, hardenability of steel may be deteriorated, which makes it difficult to secure the strength of steel, whereas the manufacturing cost may be increased when Cr is added at an excessive content of greater than 1.2%. Therefore, Cr is used at a limited content of 0.8 to 1.2%.
- Molybdenum (Mo) is an alloying element that is effective to give hardenability to steel. And it has been also known as an element that prevents sulfide corrosion cracking. Also, Mo is an effective element to secure the strength of steel through the precipitation of fine carbide after the quenching-tempering process. Therefore, Mo is added in a content range of 0.15 to 0.8%.
- Nickel (Ni) is a very effective element to improve low-temperature toughness of steel. However, since Ni is a very expensive element, Ni is added at a content of 1.0% or less according to one exemplary embodiment of the present invention.
- Phosphorus (P) is an element that adversely affects low-temperature toughness of steel.
- P is used at a content of 0.015% or less according to one exemplary embodiment of the present invention.
- S sulfur
- S is an element that adversely affects low-temperature toughness of steel.
- a removal process of S in a steel-making process is very expensive. Therefore, S is used at a content of 0.015% or less.
- Calcium (Ca) functions to reduce anisotropy of materials according to the rolling directions after the spheroidization and rolling of an inclusion, such as MnS, that is extended in a rolling direction.
- an inclusion such as MnS
- Ca is used at a limited content of 0.0005 to 0.002%.
- B Boron (B) is a core element added in the present invention that is able to enhance the hardenability of steel, which leads to the strengthening of steel.
- B is less than 0.0005%, it is difficult to expect significant improvement in the hardenability of steel.
- B is added at an excessive content of greater than 0.0025%, its addition effect is not further improved. Therefore, B is used at a limited content of 0.0005 to 0.0020%.
- Titanium (Ti) functions as an element that maximizes the addition effect of B.
- Ti is added at a content of 0.005% or more.
- the depth of the softening layer formed by the decarburization may be reduced to a depth of 1 mm or less, which leads to the minimized deterioration of steel strength.
- the manufacturing cost may be increased when Ti is added at an excessive content of greater than 0.025%. Therefore, Ti is added at a limited content of 0.005 to 0.025%.
- a steel ingot was re-heated at 1000 to 125O 0 C so as to prepare a steel according to one exemplary embodiment of the present invention.
- a re-heating temperature is below 1000 0 C, it is difficult to form solute components into a solid solution, whereas physical properties of steel may be deteriorated due to a very coarse size distribution of austenite crystal grains when the re-heating temperature exceeds 125O 0 C.
- a rolling finish temperature is defined to a temperature range of 75O 0 C to
- a steel sheet rolled under the above-mentioned conditions is subject to the conventional normalizing heat treatment so that a microstructure of the steel sheet can have a triphase structure of ferrite, bainite and martensite.
- This triphase structure may be regarded as structure that is used to curtail a time for spheroidization heat treatment to a desired time according to one exemplary embodiment of the present invention, as well as to have an effect to increase the strength of martensite and bainite.
- the steel which has the above-mentioned triphase structure so that the microstructure of the steel can be composed of 10 to 40% of ferrite, 10 to 40% of bainite and 20 to 80% of martensite, is prepared according to one exemplary embodiment of the present invention.
- a very high fraction of ferrite and very low fractions of bainite and martensite leads to the deteriorated strength of steel, whereas the very high fraction of ferrite results in the deteriorated deep drawing property of steel.
- the steel prepared under the above-mentioned conditions is subject to the spheroidization heat treatment, such that suitable workability can be given to the steel prior to the deep drawing process.
- the steel having a tensile strength of 700MPa or less is prepared prior to the deep drawing process by maintaining the heat- treated steel at a temperature of Ac to Ac for at least 30 minutes, preferably for 30 to 90 minutes.
- the temperature of Ac to Ac is in a temperature range for spheroidization heat treatment according to one exemplary embodiment of the present invention. When the spheroidization heat treatment is carried out at a temperature below the above temperature range, the spheroidization time is too long.
- the spheroidization heat treatment is carried out at a temperature greater than the above temperature range, a phase transformation into austenite may be caused, which makes it difficult to form spheroidized carbides. Therefore, the spheroidization heat treatment is carried out in the temperature range of Ac to Ac .
- the quenched steel is tempered at 550 to 625 0 C.
- the tempering temperature is below 55O 0 C, it is difficult to secure the toughness of steel, whereas it is difficult to secure the strength of steel when the tempering temperature exceeds 625 0 C.
- the steel for deep drawing used for a high-pressure container has a tensile strength of approximately 1200 MPa, and shows its low-temperature impact toughness at -5O 0 C of 37 Joules or more as well. Therefore, it is revealed that the steel for deep drawing shows its wide utilities and very excellent physical properties. Also, when steel articles are subject to the spheroidization heat treatment, the depth of the softening layer is significantly reduced compared to the conventional steel articles due to the decar- burization in a surface of the steel, which makes it possible to solve the above problem associated with the deteriorated strength of the steel caused by the heat treatment.
- Mode for the Invention is
- Spheroidization time a minimum time (min) for spheroidization heat treatment to obtain a steel having a tensile strength of 650 MPa after the spheroidization heat treatment
- Depth of softening layer depth a depth (mm) of a softening layer, which is subject to the decarburization, from a surface of steel after the deep drawing and heat treatment processes
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- 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)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN2008801146639A CN101849028B (en) | 2007-11-07 | 2008-09-12 | High tensile steel for deep drawing and manufacturing method thereof |
US12/741,703 US8652273B2 (en) | 2007-11-07 | 2008-09-12 | High tensile steel for deep drawing and manufacturing method thereof and high-pressure container produced thereof |
EP08847149.5A EP2215280B1 (en) | 2007-11-07 | 2008-09-12 | High tensile steel for deep drawing and manufacturing method thereof |
JP2010532987A JP5372944B2 (en) | 2007-11-07 | 2008-09-12 | Deep drawing high strength steel and manufacturing method thereof |
Applications Claiming Priority (2)
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KR10-2007-0113290 | 2007-11-07 | ||
KR1020070113290A KR100967030B1 (en) | 2007-11-07 | 2007-11-07 | High Tensile Steel for Deep Drawing and Manufacturing Method Thereof |
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WO2009061073A1 true WO2009061073A1 (en) | 2009-05-14 |
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PCT/KR2008/005432 WO2009061073A1 (en) | 2007-11-07 | 2008-09-12 | High tensile steel for deep drawing and manufacturing method thereof |
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US (1) | US8652273B2 (en) |
EP (1) | EP2215280B1 (en) |
JP (1) | JP5372944B2 (en) |
KR (1) | KR100967030B1 (en) |
CN (1) | CN101849028B (en) |
WO (1) | WO2009061073A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN101862798A (en) * | 2010-03-15 | 2010-10-20 | 晋西工业集团有限责任公司 | Method for composite forming of jar mouth type large-caliber thin-wall pipe |
CN102191438A (en) * | 2010-03-18 | 2011-09-21 | 宝山钢铁股份有限公司 | Steel plate for seamless high pressure gas cylinder, and manufacture method thereof |
Families Citing this family (5)
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KR101253885B1 (en) * | 2010-12-27 | 2013-04-16 | 주식회사 포스코 | Steel sheet fir formed member, formed member having excellent ductility and method for manufacturing the same |
CN104561823B (en) * | 2013-10-09 | 2016-12-07 | 宝钢特钢有限公司 | A kind of deep-draw superhigh intensity steel hot rolled steel plate and manufacture method |
KR101536478B1 (en) * | 2013-12-25 | 2015-07-13 | 주식회사 포스코 | Pressure vessel steel with excellent low temperature toughness and sulfide stress corrosion cracking, manufacturing method thereof and manufacturing method of deep drawing article |
KR101581557B1 (en) * | 2014-05-30 | 2015-12-30 | 현대제철 주식회사 | Part for generating unit and method of manufacturing the same |
TWI711708B (en) * | 2019-11-27 | 2020-12-01 | 中國鋼鐵股份有限公司 | Method for increasing spheroidization rate of chrome molybdenum steel material |
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2007
- 2007-11-07 KR KR1020070113290A patent/KR100967030B1/en active IP Right Grant
-
2008
- 2008-09-12 EP EP08847149.5A patent/EP2215280B1/en not_active Not-in-force
- 2008-09-12 CN CN2008801146639A patent/CN101849028B/en not_active Expired - Fee Related
- 2008-09-12 US US12/741,703 patent/US8652273B2/en not_active Expired - Fee Related
- 2008-09-12 WO PCT/KR2008/005432 patent/WO2009061073A1/en active Application Filing
- 2008-09-12 JP JP2010532987A patent/JP5372944B2/en not_active Expired - Fee Related
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KR19980073737A (en) * | 1997-03-18 | 1998-11-05 | 박운서 | High toughness cr-mo steel |
JP2000273582A (en) * | 1999-03-26 | 2000-10-03 | Japan Casting & Forging Corp | Cast steel for pressure vessel and production of pressure vessel using the same |
JP2004285456A (en) * | 2003-03-25 | 2004-10-14 | Japan Steel Works Ltd:The | Cr-Mo STEEL HAVING EXCELLENT STRENGTH AND LOW-TEMPERATURE TOUGHNESS, AND ITS MANUFACTURING METHOD |
KR100711373B1 (en) * | 2005-12-21 | 2007-04-30 | 주식회사 포스코 | Deep drawable steel for manufacturing pressure vessel used at low temperature having 1200mpa grade tensile strength, producing method of said steel and producing method of said pressure vessel |
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
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CN101862798A (en) * | 2010-03-15 | 2010-10-20 | 晋西工业集团有限责任公司 | Method for composite forming of jar mouth type large-caliber thin-wall pipe |
CN102191438A (en) * | 2010-03-18 | 2011-09-21 | 宝山钢铁股份有限公司 | Steel plate for seamless high pressure gas cylinder, and manufacture method thereof |
Also Published As
Publication number | Publication date |
---|---|
CN101849028A (en) | 2010-09-29 |
US20100236672A1 (en) | 2010-09-23 |
EP2215280A4 (en) | 2014-10-01 |
KR100967030B1 (en) | 2010-06-30 |
EP2215280A1 (en) | 2010-08-11 |
EP2215280B1 (en) | 2017-12-13 |
JP2011504549A (en) | 2011-02-10 |
KR20090047234A (en) | 2009-05-12 |
US8652273B2 (en) | 2014-02-18 |
JP5372944B2 (en) | 2013-12-18 |
CN101849028B (en) | 2012-08-29 |
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