冷却速率对20MnSi钢相变过程及组织的影响  

Effects of Cooling Rate on Phase Transformation Process and Microstructure of 20MnSi Steel

作　　者：毕彦 冯光勇 宁保群[2] BI Yan;FENG Guangyong;NING Baoqun(School of Mechanical Engineering,Tianjin Sino-German University of Applied Sciences,Tianjin 300350,China;School of Materials Science and Engineering,Tianjin University of Technology,Tianjin 300191,China)

机构地区：[1]天津中德应用技术大学机械工程学院,天津300350 [2]天津理工大学材料科学与工程学院,天津300191

出　　处：《热加工工艺》2021年第24期123-126,共4页Hot Working Technology

基　　金：天津市教委科研计划项目(2018KJ262);天津市企业科技特派员项目(19JCTPJC44600)。

摘　　要：利用高精度差分膨胀仪测量了20MnSi螺纹钢过冷奥氏体在不同冷却速率(10~3000℃/min)下的相变行为。根据线膨胀曲线特征,系统研究了20MnSi钢在连续冷却过程中冷却速率对过冷奥氏体转变及最终组织的影响,并进一步确定了在各冷速下的相变温度区间及转变产物。结果表明,在冷速为10~200℃/min时,20MnSi钢冷却过程中只有铁素体和珠光体两个转变区,并随冷速的增加珠光体含量相对增多;冷速为500℃/min时出现了贝氏体转变区;在1000℃/min的冷速下出现了马氏体转变区;在冷速为2000℃/min时铁素体转变被抑制,室温组织为贝氏体、马氏体及极少量的珠光体组织;3000℃/min的冷速时冷却过程中只有贝氏体和马氏体两个不连续转变区,最终组织为贝氏体和马氏体。The phase transformation behavior of undercooled austenite of 20MnSi thread steel bars under different cooling rates(10-3000℃/min)was measured by using a high-precision differential dilatometer.According to the characteristics of the linear expansion curve,the influence of the cooling rate of 20MnSi steel during the continuous cooling process on the transformation of undercooled austenite and the final structure were systematically studied,which determined the phase transition temperature of the sample and the volume fraction of the conversion product at each cooling rate deeply.The results show that there are only two transformation zones of ferrite and pearlite in the cooling process of 20MnSi steel when the cooling rate is 10-200℃/min,and the content of pearlite increases with the increase of cooling rate.The bainite transformation zones appear as the cooling rate reaches at 500℃/min and the martensite transformation zones appear as the cooling rate reaches at 1000℃/min.The ferrite transformation is inhibited at the cooling rate of 2000℃/min.The bainite,martensite and a very small amount of pearlite are obtained at room temperature.And at the cooling rate of 3000℃/min,there are only two discontinuous transformation zones of bainite and martensite,and the final microstructure is bainite and martensite.

关 键 词：20MNSI钢 冷却速率 相变过程 显微组织 

分 类 号：TG161[金属学及工艺—热处理] TG172[金属学及工艺—金属学]