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：Kai Yang Yi Luo Wei Li Li Wang Zhong-qu Sun Jun-liang Liu Xue-jun Jin 

机构地区：[1]Bao Steel-SJTU Joint Research Center of Future Steels,School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China [2]State Key Lab of Metal Matrix Composites,School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China [3]State Key Lab of Development and Application Technology of Automotive Steels(Bao Steel),Research Institute(R&D Center),Baoshan Iron&Steel Co.,Ltd.,Shanghai 200240,China

出　　处：《Journal of Iron and Steel Research International》2023年第4期782-794,共13页

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).

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.

关 键 词：Quenched and partitioned steel Isothermal bainite transformation Transition carbide Hydrogen embrittlement Impact toughness 

分 类 号：TG142[一般工业技术—材料科学与工程]