EP2022865A1 - Tôle d'acier de très haute résistance et pièce de renfort pour automobile l'utilisant - Google Patents

Tôle d'acier de très haute résistance et pièce de renfort pour automobile l'utilisant Download PDF

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Publication number
EP2022865A1
EP2022865A1 EP07740860A EP07740860A EP2022865A1 EP 2022865 A1 EP2022865 A1 EP 2022865A1 EP 07740860 A EP07740860 A EP 07740860A EP 07740860 A EP07740860 A EP 07740860A EP 2022865 A1 EP2022865 A1 EP 2022865A1
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EP
European Patent Office
Prior art keywords
steel sheet
mass
strength
ultrahigh
ultrahigh strength
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP07740860A
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German (de)
English (en)
Inventor
Hideyuki Sasaoka
Masamoto Ono
Eizaburou Nakanishi
Yoshio Okada
Tadanobu Inoue
Yuuji Kimura
Kotobu Nagai
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nissan Motor Co Ltd
Original Assignee
Nissan Motor Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nissan Motor Co Ltd filed Critical Nissan Motor Co Ltd
Publication of EP2022865A1 publication Critical patent/EP2022865A1/fr
Withdrawn legal-status Critical Current

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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
    • C22C38/02—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
    • C22C38/18—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
    • C22C38/40—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

Definitions

  • the present invention relates to an ultrahigh strength steel sheet having good moldability and high delayed fracture resistance and an automotive strength part using the ultrahigh strength steel sheet.
  • the material strength of the ultrahigh strength steel sheets can be secured by various strengthening techniques, the workability of the ultrahigh strength steel sheets significantly decreases with increase in strength due to structural heterogeneity, local hard/soft phase coexistence and the like so that it is difficult for the ultrahigh strength steel sheets to combine both of high strength and moldability under the current circumstances. Further, the ultrahigh strength steel sheets face another problem of delayed fracture due to hydrogen embrittlement when the strength of the ultrahigh strength steel sheets becomes 1180 MPa or higher.
  • TRIP Transformation Induced Plasticity
  • Non-Patent Document 1 reports that the delayed fracture of the TRIP steel sheet gets promoted by deformation induced transformation of retained austenite.
  • Patent Document 1 proposes a high strength steel sheet having improved delayed facture resistance by the formation of a deposit of niobium (Nb), but provides no findings about the moldability of the high strength steel sheet. There has been a demand for the ultrahigh strength steel sheets to combine both of moldability and delayed fracture resistance.
  • the present invention has been made to solve the above prior art problems. It is an object of the present invention to provide an ultrahigh strength steel sheet having good moldability and high delayed fracture resistance and an automotive strength part using the ultrahigh strength steel sheet.
  • an ultrahigh strength steel sheet comprising 0.10 to 0.40 mass% of C, 0.01 to 3.5 mass% of Cr, at least one selected from the group consisting of 0.10 to 2.0 mass% of Mo, 0.20 to 1.5 mass% of W, 0.002 to 1.0 mass% of V, 0.002 to 1.0 mass% of Ti and 0.005 to 1.0 mass% of Nb, 0.02 mass% or less of P and 0.01 mass% or less of S as impurities and the balance being Fe and unavoidable impurities based on the total mass of the steel sheet and having a base structure of either lower bainite, tempered lower bainite or tempered martensite, a prior austenite grain size of 30 ⁇ m or smaller and a tensile strength of 980 MPa or higher.
  • an automotive strength part using the ultrahigh strength steel sheet is provided.
  • the ultrahigh strength steel sheet of the present invention contains molybdenum (Mo), tungsten (W), vanadium (V), titanium (Ti), niobium (Nb) or any combination thereof. Further, the ultrahigh strength steel sheet of the present invention has a base structure of lower bainite, tempered lower bainite or tempered martensite and a prior austenite grain size of 30 ⁇ m or smaller.
  • the steel sheet attains a tensile strength of 980 MPa or higher when the base structure of the steel sheet is formed by a hard phase of lower bainite, tempered lower bainite or tempered martensite. It is more preferable that the steel sheet has a tensile strength of 1180 MPa or higher.
  • the tempered lower bainite phase is formed, after heating to 1100°C or higher, under the manufacturing conditions of a finishing temperature of 850°C or higher, a rolling draft of 30% or higher and a holding temperature of 300 to 500°C and under the tempering conditions of a tempering temperature of 400 to 700°C.
  • the tempered martensite phase is generally formed, after heating to 1100°C or higher, under the manufacturing conditions of a finishing temperature of 850°C or higher, a rolling draft of 30% or higher and a holding temperature of 150 to 300°C and under the tempering conditions of a tempering temperature of 550 to 700°C.
  • the prior austenite grain size of the steel sheet is controlled to within a small grain size range of 1 to 30 ⁇ m.
  • the steel sheet cannot expect improvements in deep drawability, stretch formability and shape fixability when the prior austenite grain size exceeds 30 ⁇ m.
  • the prior austenite grain size is less than 1 ⁇ m, the steel sheet is likely to deteriorate in mechanical properties and to be difficult to manufacture. It is particularly desirable to control the prior austenite grain size of the steel sheet to within 3 to 10 ⁇ m in order that the steel sheet obtains further improvements in deep drawability, stretch formability and shape fixability and thereby attains sufficient moldability required for automotive part molding.
  • the ultrahigh strength steel sheet of the present invention comprises 0.10 to 0.40% carbon (C), 0.01 to 3.5% chromium (Cr), at least one selected from the group consisting of 0.10 to 2.0% molybdenum (Mo), 0.20 to 1.5% tungsten (W), 0.002 to 1.0% vanadium (V), 0.002 to 1.0% titanium (Ti) and 0.005 to 1.0% niobium (Nb), 0.02% or less phosphorus (P) and 0.01% or less sulfur (S) as impurities and the balance substantially being iron (Fe) and unavoidable impurities based on the total mass of the steel sheet.
  • C carbon
  • Cr chromium
  • the ultrahigh strength steel sheet contains either one or both of 0.1 to 3.0% copper (Cu) and 0.1 to 3.0% nickel (Ni) as an additive component or components. It is also preferable that the ultrahigh strength steel sheet contains either one or both of 0.01 to 2.5% silicon (Si) and 0.1 to 1.0% manganese (Mn) as an additive component or components. Preferably, the ultrahigh strength steel sheet further contains 0.001 to 0.1% aluminum (Al) as an additive component.
  • the steel sheet is able to not only secure good moldability but also attain high delayed fracture resistance by formation of fine alloy carbide.
  • Carbon (C) is the most effective element for increasing the strength of the steel sheet.
  • the C content of the steel sheet is 0.10% or higher.
  • the C content of the steel sheet exceeds 0.4%, however, the steel sheet is likely to decrease in toughness.
  • the C content of the steel sheet is thus controlled to within 0.10 to 0.40%.
  • Chromium (Cr) is an effective element for improving the hardenability of the steel sheet and increasing the strength of the steel sheet by dissolving in cementite. It is desirable that the Cr content of the steel sheet is at least 0.01 % or higher, more desirably 1% or higher. When an excessive amount of Cr is added to the steel sheet, however, it turns out that the effect of the Cr element becomes saturated and that the steel sheet decreases in toughness. The upper limit of the Cr content of the steel sheet is thus set to 3.5%.
  • Molybdenum (Mo) is one of the most critical elements to the ultrahigh strength steel sheet of the present invention and is effective for not only improving the hardenability of the steel sheet but also decreasing the grain size of the steel sheet by formation of alloy carbide and promoting substitution of hydrogen in the steel sheet.
  • Mo content of the steel sheet is less than 0.10%, the alloy carbide is unlikely to be formed.
  • Mo is an expensive alloying element. The Mo content of the steel sheet is thus controlled to within 0.1 to 2.0%.
  • the steel sheet contains at least one element selected from Mo, W, V, Ti and Nb in order to secure not only good moldability but also high delayed fracture resistance.
  • the W content, V content, Ti content and Nb content of the steel sheet are controlled to within 0.20 to 1.5%, 0.002 to 1.0%, 0.002 to 1.0% and 0.005 to 1.0%, respectively.
  • Phosphorus (P) causes a decrease in the grain boundary strength of the steel sheet. It is thus desirable to minimize the P content of the steel sheet.
  • the upper limit of the P content of the steel sheet is set to 0.02%
  • S Sulfur
  • the upper limit of the S content of the steel sheet is set to 0.01 %.
  • Copper (Cu) is an effective element for strengthening the steel sheet and contributes to prevention of delayed fracture by fine deposit thereof. It is desirable that the Cu content of the steel sheet is 0.1% or more. However, the excessive addition of Cu results in workability deterioration.
  • the upper limit of the Cu content of the steel sheet is thus preferably set to 3.0%.
  • Nickel (Ni) is an effective element for improving the hardenability of the steel sheet for sufficient steel sheet strength and increasing the corrosion resistance of the steel sheet.
  • the Ni content of the steel sheet is less than 1 %, the Ni element does not produce a desired effect.
  • the Ni content of the steel sheet exceeds 3.0%, the steel sheet deteriorates in workability. It is thus desirable to control the Ni content of the steel sheet to within 0.1 to 3.0%.
  • Silicon (Si) is an effective element for deoxidation and strength improvement. It is desirable that the steel sheet contains 0.2% or more Si including some added as a deoxidant and remaining in the steel sheet. However, the excessive addition of Si results in toughness deterioration.
  • the upper limit of the Si content of the steel sheet is thus preferably set to 2.5%.
  • Manganese (Mn) is an effective element for strength improvement. When the Mn content of the steel sheet is less than 0.1, the Mn element is unlikely to produce a desired effect. By contrast, it turns out that the cosegregation of P and S becomes promoted and that the steel sheet decreases in toughness when an excessive amount of Mn is added to the steel sheet.
  • the Mn content of the steel sheet is thus preferably controlled to within 0.1 to 1.0%.
  • Aluminum (Al) is added for deoxidation.
  • Al Aluminum
  • the Al content of the steel sheet is thus preferably controlled to within 0.001 to 0.1%.
  • the ultrahigh strength steel sheet of the present invention can be processed by either hot rolling or cold rolling because of its good moldability.
  • the thickness of the ultrahigh strength steel sheet is generally 0.5 to 2.3 mm.
  • the ultrahigh strength steel sheet may be surface treated by zinc plating or treated by film lamination.
  • the automotive strength part of the present invention is produced from the above-explained ultrahigh strength steel sheet and thus combines good moldability and high delayed fracture resistance. More specifically, the automotive strength part is produced by subjecting the high strength steel sheet to any of press forming process (cold press forming, warm press forming, hot press forming), hydroform process and blow molding process.
  • press forming process cold press forming, warm press forming, hot press forming
  • hydroform process blow molding process
  • a component part has a high risk of delayed fracture due to a large residual stress when processed by cutting e.g. piercing or trimming. Even with such a cut-processed portion, the automotive strength part of the present invention has less delayed fracture and thus can be used effectively.
  • Steel sheets of Examples 1 to 5 and Comparative Examples 1 to 6 were formed from various steel materials.
  • the compositions of the steel materials and the manufacturing conditions of the steel sheets are indicated in TABLES 1 and 2.
  • Each of the steel sheets was tested for mechanical properties such as tensile strength and SD (stress decrease after uniform elongation), structure, moldability and delayed fracture susceptibility by the following procedures.
  • the tensile strength was evaluated by preparing a No.5 test piece according to JIS Z 2201 and carrying out a tensile test on the test piece according to JIS Z 2241.
  • FIG. 1 shows a schematic stress-strain diagram of a plate-shaped test piece, such as a No. 5 test piece or No.13 test piece according to JIS Z 2201, under tensile test.
  • the toughness/ductility was evaluated as "good” when the test piece had a stress decrease (SD) of 180 MPa or greater on the definition of the stress decrease (SD) as a difference between tensile strength (TS) and breaking strength.
  • SD stress decrease
  • TS tensile strength
  • the base structure was evaluated by preparing a test piece, grinding a cross section of the test piece, etching the cross section of the test piece with a nital solution and then observing the cross section of the test piece with a magnification of 100 to 1000 times by optical microscope and with a magnification of 1000 to 5000 times by scanning electron microscope.
  • the prior austenite grain size was evaluated according to JIS G0551.
  • the evaluation of the prior austenite grain size was herein made on the test piece having a base structure of lower bainite.
  • the moldability was rated in three levels: " ⁇ (good)”, “ ⁇ (ordinary)” and “ ⁇ (bad)” based on the deep drawability, stretch formability and shape fixability in view of the application to intricate press-molded automotive parts.
  • the deep drawability, stretch formability and shape fixability were evaluated by the following procedures.
  • FIG. 2 outlines a deep drawing test.
  • the ratio D/d p between the maximum blank diameter to the punch diameter was defined as a limiting drawing ratio LDR where D was the maximum blank diameter at which cylindrical drawing was accomplished with no fracture and d p was the punch diameter.
  • a test tool unit was used including a cylindrical punch 4 of 5 mm in punch shoulder radius and 50 mm in diameter d p , a die 1 of 7 mm in die shoulder radius and a wrinkle suppressor 2 in such a manner as to move the punch 4 at a speed of 3 mm/sec with 50 kN of pressure applied to the wrinkle suppressor 2.
  • the maximum blank diameter D was measured by preparing test pieces 3 from the steel sheet of each example, subjecting the test pieces 3 to deep drawing with increasing blank diameters, and then, determining the blank diameter at which the test piece was completely drawn with no fracture as the maximum blank diameter D.
  • the limiting drawing ratio LDR was calculated as the ratio D/50 between the maximum blank diameter and the punch diameter.
  • the deep drawability was evaluated as "good" for a larger LDR value.
  • FIG. 3 outlines a stretch forming test.
  • the drawing height immediately before the occurrence of fracture during spherical-head stretch forming was defined as a limiting drawing height LDH.
  • a test tool unit including a spherical-headed punch 4 of 50 mm in radius, a beaded die 1 of 5 mm in die shoulder radius and a wrinkle suppressor 2 in such a manner as to move the punch 4 at a speed of 10 mm/sec with high pressure applied to the wrinkle suppressor 2 to avoid material inflow from the surroundings.
  • a test piece 3 of 200mm ⁇ 200mm was prepared from the steel sheet of each example. The moving distance from the point of contact between the test piece 3 and the punch 4 to the point immediately before the fracture was measured as the limiting drawing height LDH.
  • the stretch formability was evaluated as "good" for a larger LDH value.
  • FIG. 4 outlines a hat bending test for evaluating a shape fixability factor.
  • a test tool unit including a punch 4 of 75 mm in width and 5 mm in punch shoulder radius, a die 1 of 5 mm in die shoulder radius and a wrinkle suppressor 2 in such a manner as to move the punch 4 by 80 mm at a speed of 10 mm/sec with 200 kN of pressure applied to the wrinkle suppressor 2.
  • a test piece 3 of 300mm ⁇ 50mm was prepared from the steel sheet of each example. After subjecting the test piece 3 to hat bending, the test piece 3 was taken out of the test unit. The curvature of the test piece 3 was then measured in the manner shown in FIG. 5 . The shape fixability was evaluated as "good" for a larger curvature value.
  • the delayed fracture resistance was evaluated as " ⁇ (not cracked)” or " ⁇ (cracked)" by preparing a strip test piece of 100mm ⁇ 50mm from the steel sheet of each example, bending the test piece by a hat bending test machine, unbending the test piece, subjecting a wall section of the test piece to piercing, immersing the test piece in a 0.1mol/m 3 aqueous hydrochloric acid solution for 100 hours, and then, examining the occurrence or nonoccurrence of a crack in the test piece.
  • the ultrahigh strength steel sheets of Examples 1 to 5 had a tensile strength of 980 MPa or higher and showed sufficient deep drawability, stretch formability and shape fixability to satisfy the requirements for automotive parts. No crack occurred in the ultrahigh strength steel sheets of Examples 1 to 5 in the delayed fracture test. It can be thus concluded that the ultrahigh strength steel sheets of Examples 1 to 5 combined moldability and delayed fracture resistance.
  • the steel sheets of Comparative Examples 1 and 2 had a tensile strength of 980 MPa but did not combine moldability and delayed fracture resistance as the prior austenite grain size of the steel sheet of Comparative Example 1 and the base structure of the steel sheet of Comparative Example 2 were out of the scope of the present invention.
  • the base structures and compositions of the steel sheets of Comparative Examples 3 to 6 (commercial products) were out of the scope of the present invention. Some of the steel sheets of Comparative Examples 3 to 6 had a tensile strength of less than 980 MPa. The steel sheets of Comparative Examples 3 to 6 had no problem in delayed fracture resistance but were inferior in moldability to those of Examples 1 to 5.
  • Steel sheets of Examples 6 to 10 and Comparative Examples 7 and 8 were formed using various steel materials of TABLE 1 under the manufacturing/tempering conditions of TABLE 4. Each of the steel sheets was tested for mechanical properties such as tensile strength and SD (stress decrease after uniform elongation), structure, moldability and delayed fracture resistance in the same manners as above. The evaluation of the prior austenite grain size was herein made on the steel sheet having a base structure of tempered lower bainite.
  • the ultrahigh strength steel sheets of Examples 6 to 10 had a tensile strength of 980 MPa or higher and showed sufficient deep drawability, stretch formability and shape fixability to satisfy the requirements for automotive parts. No crack occurred in the ultrahigh strength steel sheets of Examples 6 to 10 in the delayed fracture test. It can be thus concluded that the ultrahigh strength steel sheets of Examples 6 to 10 combined moldability and delayed fracture resistance.
  • the steel sheets of Comparative Examples 7 and 8 had a tensile strength of 980 MPa but did not combine moldability and delayed fracture resistance as the prior austenite grain size of the steel sheet of Comparative Example 7 and the base structure of the steel sheet of Comparative Example 8 were out of the scope of the present invention.
  • the above-mentioned steel sheets of Comparative Examples 3 to 6 (commercial products) were also inferior in moldability to the steel sheets of Examples 6 to 10.
  • Steel sheets of Examples 11 to 15 and Comparative Example 9 were formed using various steel materials of TABLE 1 under the manufacturing/tempering conditions of TABLE 6. Each of the steel sheets was tested for mechanical properties such as tensile strength and SD (stress decrease after uniform elongation), structure, moldability and delayed fracture resistance in the same manners as above. The evaluation of the prior austenite grain size was herein made on the steel sheet having a base structure of tempered martensite.
  • the ultrahigh strength steel sheets of Examples 11 to 15 had a tensile strength of 980 MPa or higher and showed sufficient deep drawability, stretch formability and shape fixability to satisfy the requirements for automotive parts. No crack occurred in the ultrahigh strength steel sheets of Examples 11 to 15 in the delayed fracture test. It can be thus concluded that the ultrahigh strength steel sheets of Examples 11 to 15 combined moldability and delayed fracture resistance.
  • the steel sheet of Comparative Example 9 had a tensile strength of 980 MPa but did not combine moldability and delayed fracture resistance as the prior austenite grain size of the steel sheet of Comparative Example 9 was out of the scope of the present invention.
  • the above-mentioned steel sheets of Comparative Examples 3 to 6 (commercial products) were also inferior in moldability to the steel sheets of Examples 11 to 15.
  • the steel sheet has the excellent effects of attaining not only sufficient moldability required for automotive parts as compared to conventional high strength steel sheets but also improved delayed fracture resistance, while securing a tensile strength of 980 MPa, by forming the base structure of the steel sheet from either lower bainite, tempered lower bainite or tempered martensite and reducing the prior austenite grain size of the steel sheet. It is therefore possible to provide the industrially useful ultrahigh strength steel sheet having both of moldability and delayed fracture resistance and the automotive strength part using the ultrahigh strength steel sheet.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
EP07740860A 2006-05-17 2007-04-03 Tôle d'acier de très haute résistance et pièce de renfort pour automobile l'utilisant Withdrawn EP2022865A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2006137227 2006-05-17
JP2006137226 2006-05-17
JP2006137225 2006-05-17
PCT/JP2007/057424 WO2007132600A1 (fr) 2006-05-17 2007-04-03 TÔle d'acier de trÈs haute rÉsistance et piÈce de renfort pour automobile L'utilisant

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EP2022865A1 true EP2022865A1 (fr) 2009-02-11

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EP07740860A Withdrawn EP2022865A1 (fr) 2006-05-17 2007-04-03 Tôle d'acier de très haute résistance et pièce de renfort pour automobile l'utilisant

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US (1) US20090236015A1 (fr)
EP (1) EP2022865A1 (fr)
WO (1) WO2007132600A1 (fr)

Cited By (3)

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CN102162068A (zh) * 2010-02-21 2011-08-24 宝山钢铁股份有限公司 一种弹簧钢及其制造和热处理方法
CN107760983A (zh) * 2016-08-18 2018-03-06 江苏鼎泰工程材料有限公司 一种低合金超高强度钢及其铸件的生产方法
CN110358971A (zh) * 2019-06-20 2019-10-22 天津大学 一种屈服强度1300MPa级的低碳超高强钢及其制备方法

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KR20210062726A (ko) 2017-03-01 2021-05-31 에이케이 스틸 프로퍼티즈 인코포레이티드 극도로 높은 강도를 갖는 프레스 경화 강
WO2023246898A1 (fr) * 2022-06-22 2023-12-28 宝山钢铁股份有限公司 Acier à haute plasticité et son procédé de fabrication

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JP2671718B2 (ja) * 1992-06-12 1997-10-29 大洋製鋼 株式会社 高耐久性表面処理金属板およびその製造方法
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JP4412727B2 (ja) * 2004-01-09 2010-02-10 株式会社神戸製鋼所 耐水素脆化特性に優れた超高強度鋼板及びその製造方法

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102162068A (zh) * 2010-02-21 2011-08-24 宝山钢铁股份有限公司 一种弹簧钢及其制造和热处理方法
CN102162068B (zh) * 2010-02-21 2013-07-31 宝山钢铁股份有限公司 一种弹簧钢及其制造和热处理方法
CN107760983A (zh) * 2016-08-18 2018-03-06 江苏鼎泰工程材料有限公司 一种低合金超高强度钢及其铸件的生产方法
CN107760983B (zh) * 2016-08-18 2019-03-01 江苏鼎泰工程材料有限公司 一种低合金超高强度钢及其铸件的生产方法
CN110358971A (zh) * 2019-06-20 2019-10-22 天津大学 一种屈服强度1300MPa级的低碳超高强钢及其制备方法

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WO2007132600A1 (fr) 2007-11-22

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