Competitive role of film-like austenite and transition carbides on hydrogen embrittlement resistance and impact toughness in bainite-containing quenched and partitioned steel
作者机构：Bao Steel-SJTU Joint Research Center of Future SteelsSchool of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China State Key Lab of Metal Matrix CompositesSchool of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China State Key Lab of Development and Application Technology of Automotive Steels(Bao Steel)Research Institute(R&D Center)Baoshan Iron&Steel Co.Ltd.Shanghai 200240China
出 版 物：《Journal of Iron and Steel Research(International)》 (钢铁研究学报（英文版）)
年 卷 期：2023年第30卷第4期
页 面：782-794页
核心收录：
学科分类：08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 0703[理学-化学]
基 金：the National Key R&D Program of China(No.2021YFB3702401) Major Program of the National Natural Science Foundation of China(No.52293394) the National Natural Science Foundation of China(Nos.U1564203,51571141 and 51201105).
主 题：Quenched and partitioned steel Isothermal bainite transformation Transition carbide Hydrogen embrittlement Impact toughness
摘 要：A microstructure composed of martensite matrix,lower bainite,and stable film-like austenite was designed by a quenching and isothermal bainitic holding process in a 0.30C–2.69Mn–1.71Si(wt.%)steel.The yield strength,tensile strength,and ductile-to-brittle transition temperature(DBTT)of the high-strength steel thus obtained were 1263 MPa,1521 MPa,and-33℃,respectively,and at-20℃,it showed superior low-temperature toughness,which reached 77.5 J/cm^(2).Meanwhile,it showed excellent hydrogen embrittlement(HE)resistance,and the total elongation loss is only 3.1%after 15 min of hydrogen charging.The excellent comprehensive performance is attributed to the fact that fine stable austenite with film-like morphology hindered the crack nucleation and propagation,and hindered hydrogen diffusion as a hydrogen trap.However,with a decrease in the isothermal temperature,transition carbide precipitation was accompanied by a further decrease in austenite grain size.For this condition,although transition carbides can act as effective hydrogen traps,excessive precipitation decreased the carbon content of retained austenite and increased the deformation heterogeneity between austenite and martensite matrix,leading to weakened austenite stability and HE resistance,a total elongation loss of approximately 39%(15 min hydrogen charging),a sharp decrease in impact toughness,and an increase in DBTT.The competitive role of film-like austenite and transition carbides on the comprehensive mechanical performance of steel is revealed,especially the suppression of crack nucleation and propagation that will provide a guide for the design of high strength steels with excellent impact toughness and HE resistance.
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