首页|1 300 MPa级中厚板的奥氏体连续冷却行为及淬透性分析

1 300 MPa级中厚板的奥氏体连续冷却行为及淬透性分析

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超高强中厚板因其超高的强度、良好的塑韧性以及焊接性能被广泛应用于工程机械以及工业防护领域.为研究1 300 MPa级中厚板的奥氏体连续冷却行为及淬透性高低,通过热模拟试验研究了试验钢在奥氏体连续冷却过程中的组织演变、硬度以及几何必须位错密度变化规律并绘制了 CCT(Continuous Cooling Transformation)曲线,通过端淬试验测定了试验钢的淬透性,并依据上述试验结果进行了中试试验.研究结果表明,随着冷速增加,试验钢组织由铁素体+粒状贝氏体逐步转变为贝氏体+马氏体,硬度和几何必须位错密度不断增加;当冷速大于5 ℃/s后可得到全马氏体组织,此时硬度和几何必须位错密度趋于稳定,进行调质处理时的淬火冷速宜控制在5~10 ℃/s.试验钢的淬硬层深度约为30 mm,淬透性优异、可满足30 mm及以下中厚板的淬透性要求.30 mm厚中试试验钢经850 ℃淬火+180 ℃回火的调质处理后形成回火马氏体组织,其屈服强度为1 328 MPa、抗拉强度为1 684 MPa、伸长率为13.4%、-40 ℃冲击功为24.3 J,达到1 300 MPa级超高强钢水平,更高的位错密度和大角度晶界密度是其拥有高强度和良好塑韧性的主要原因,为试验钢的后续热处理工艺制定提供了依据.
Analysis on austenite continuous cooling behavior and hardenability of 1 300 MPa medium-thick plates
Ultra-high-strength medium-thick plates are widely used in the field of construction machinery and indus-trial protection due to its ultra-high strength,good plastic toughness and weldability.To study the austenitic contin-uous cooling behavior and hardenability of 1 300 MPa medium-thick plate,the microstructure evolution,hardness and geometrically necessary dislocation density of the experimental steel during continuous cooling of austenite were studied by thermal simulation experiments,and the CCT curve was drawn.The hardenability of the experimental steel was determined by end hardening test.And the trial production of experimental steel was carried out according to the above test results.The results show that with the increase of cooling rate,the microstructure of experimental steel gradually changes from ferrite+granular bainite to bainite+martensitie,and the hardness and geometric neces-sary dislocation density are increasing.When the cooling rate is greater than 5 ℃/s,the whole martensitic micro-structure can be obtained,the hardness and geometrically necessary dislocation density tend to be stable,and the cooling speed should be controlled at 5-10 ℃/s during quenching.The depth of the hardened layer of experimental steel is about 30 mm,and the hardenability is excellent,which can meet the hardenability requirements for medium-thick plates of 30 mm and below.After quenching and tempering treatment at 850 ℃+180 ℃,tempered martensitic microstructure is formed in the experimental steel of 30 mm,its yield strength is 1 328 MPa,tensile strength is 1 684 MPa,elongation is 13.4%,and-40 ℃ impact energy is 24.3 J,which has reached the level of 1 300 MPa grade high-strength steel,the higher density of dislocation and large angular grain boundaries are the main reasons for its high strength and good plastic toughness,which provides a basis for the formulation of the subsequent heat treatment process of experimental steel.

1 300 MPa medium-thick plateCCT curvemicrostructure evolutiongeometrically necessary disloca-tion densityhardenabilitymechanical property

朱海宾、赵燕青、石帅、黄新贵、王学敏

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北京科技大学钢铁共性技术协同创新中心,北京 100083

河钢材料技术研究院能源材料研发中心,河北石家庄 050023

1300 MPa级中厚板 CCT曲线 组织演变 几何必须位错密度 淬透性 力学性能

中央高校基本科研项目

FRF-BD-22-02

2024

中国冶金
中国金属学会

中国冶金

CSTPCD北大核心
影响因子:0.907
ISSN:1006-9356
年,卷(期):2024.34(9)
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