含偏析贝氏体弹簧钢的等温转变特性  

Isothermal transition characteristics of bainitic spring steels with segregation

作　　者：于金瑞 吴康俊 于鑫泓 冯以盛 赵而团[1,2] Yu Jinrui;Wu Kangjun;Yu Xinhong;Feng Yisheng;Zhao Ertuan(School of Mechanical Engineering,Shandong University of Technology,Zibo Shandong 255049,China;Starspring Technology Co.,Ltd.,Zibo Shandong 255049,China)

机构地区：[1]山东理工大学机械工程学院,山东淄博255049 [2]山东星泉科技有限公司,山东淄博255049

出　　处：《金属热处理》2024年第1期53-60,共8页Heat Treatment of Metals

基　　金：山东省自然科学基金(ZR2022ME210);山东省精密制造与特种加工重点实验室基金(9001/5322009)。

摘　　要：利用超高温激光共聚焦显微镜、OM、SEM与XRD研究了含偏析贝氏体钢等温过程中的组织演变特征。结果表明,偏析造成了混晶,晶粒尺寸从合金元素贫瘠区到富集区逐渐减小。合金元素含量越高,贝氏体孕育期越长,转变速度越慢,因此贝氏体在合金元素贫瘠区快速形核并长大,并随着等温时间的延长逐层向未转变区生长。等温过程中,残留奥氏体含量受到贝氏体转变速度与碳化物析出速度的控制而呈先增加后降低趋势。在贝氏体转变的不同阶段,偏析造成的影响不同,当贝氏体转变未完成时,贝氏体与马氏体组织有较大硬度差异并形成条带组织;贝氏体转变完成后,条带组织消除,此时偏析的影响表现为不同偏析部位合金元素、晶粒尺寸与贝氏体形貌存在差异。Microstructure evolution of bainitic steels with segregation during isothermal process was studied by means of ultra high temperature laser confocal microscope,OM,SEM and XRD.The results show that the segregation results in mixed crystals,and the grain size gradually decreases from the diluted zone to the enriched region of alloying elements.The higher the alloying element content,the longer the incubation period of bainite and the slower the transformation rate is.Therefore,the bainite structure nucleates and grows rapidly in the alloying element diluted zone,and expands to the untransformed zone layer by layer with the extension of isothermal time.During the isothermal process,the content of retained austenite increases first and then decreases under the control of bainite transformation rate and carbide precipitation rate.At different stages of bainite transformation,the effects of segregation are different.When bainite transformation is not completed,the hardness difference between bainite and martensite microstructure is large and the banded structures are formed.When the bainite transformation is completed,the banded structures are eliminated,and the segregation results in differences in alloying elements,grain size and bainite morphology at different segregation sites.

关 键 词：成分偏析 贝氏体相变 原位观察 残留奥氏体 组织演变 

分 类 号：TG124.12[金属学及工艺—金属学]