等温转变对中碳贝氏体钢组织及性能的影响  

Influence of isothermal transformation on microstructure and properties of medium-carbon bainite steels

作　　者：陈康彦 张志建 胡锋[2] 李化龙 CHEN Kang-yan;ZHANG Zhi-jian;HU Feng;LI Hua-long(Institute of Research of Iron and Steel,Shagang,Jiangsu Province,Suzhou 215625,China;Collaborative Innovation Center for Advanced Steels,International Research Institute for Steel Technology,Wuhan University of Science and Technology,Wuhan 430081,China)

机构地区：[1]江苏省(沙钢)钢铁研究院,江苏苏州215625 [2]武汉科技大学高性能钢铁材料及其应用省部共建协同创新中心(国际钢铁研究院),湖北武汉430081

出　　处：《塑性工程学报》2022年第11期209-215,共7页Journal of Plasticity Engineering

基　　金：国家自然科学基金资助项目(52130408)。

摘　　要：通过试验研究了不同等温转变温度下低温贝氏体钢的显微组织,探索了残余奥氏体的形态和稳定性对试验钢力学性能和断裂行为的影响。利用扫描电镜、透射电镜和X射线衍射对低温贝氏体钢的微观组织、拉伸及冲击断口形貌进行了表征。结果表明,随着等温转变温度的升高,试验钢的抗拉强度保持在1500 MPa以上,屈服强度由945 MPa下降至806 MPa,断后伸长率由14.0%下降至9.0%。等温转变温度对试验钢残余奥氏体的形态和稳定性有明显影响,随着等温转变温度的上升,残余奥氏体从富碳细条状和薄膜状变成贫碳块状,在塑性变形初期,这种形态的残余奥氏体大量、快速地发生应变诱发马氏体相变,为裂纹扩展提供了路径,从而降低了钢的韧性和塑性,使试验钢的拉伸和冲击断口的延性穿晶断裂特征更明显。Microstructure of low-temperature bainite steel at different isothermal transformation(IT)temperatures was studied by tests,and the influence of morphology and stability of retained austenite(RA)on mechanical properties and fracture behavior of test steel was studied.The scanning electron microscope(SEM),transmission electron microscope(TEM)and X-Ray diffraction(XRD)were used to characterize the microstructure,tensile and impact fracture morphology of low-temperature bainite steel.The results show that with the increase of IT temperature,the tensile strength of test steel remains above 1500 MPa,the yield strength decreases from 945 MPa to 806 MPa,and the elongation decreases from 14.0%to 9.0%.IT temperature has obvious influence on the morphology and stability of RA of test steel,with the increase of IT temperature,the carbon-rich thin strip RA and film RA turn into carbon-poor blocky RA.In the early stage of plastic deformation,strain induced martensitic transformation of RA with this morphology occurs in quantity and rapidly,which provides a path for crack propagation.Thus the toughness and plasticity of steel are reduced,which makes the ductile transgranular fracture characteristics of the tensile and impact fracture of test steels more obvious.

关 键 词：低温贝氏体 贝氏体转变 TRIP 拉伸断口 冲击断口 

分 类 号：TG142[一般工业技术—材料科学与工程]