摘要
采用热膨胀-显微组织-显微硬度相结合的方法,绘制了1.0 GPa级冷轧增强成形性双相钢的静态连续冷却转变曲线(CCT曲线),并研究了退火工艺对实验钢显微组织与力学性能的影响。结果表明:实验钢过冷奥氏体冷却转变过程主要存在铁素体相变区、贝氏体相变区和马氏体相变区的3个相变区;当冷速低于1℃/s时,实验钢主要发生铁素体与贝氏体相变,并存在少量马氏体相变;当冷速在3~20℃/s之间时,发生马氏体与贝氏体相变;当冷速达到30℃/s及以上时,完全发生马氏体转变。随冷却速率的增加实验钢的显微硬度逐渐增大,前期显微硬度提升较快,冷速达到20℃/s后逐渐趋于平稳,与对应冷速下的显微组织一致。实验钢的组织主要为铁素体、马氏体和残留奥氏体,三者匹配有利于变形过程基体强塑性的提升。当均热温度为810℃时,实验钢中残留奥氏体含量最高,为4.9%,变形过程中相变诱导塑性(TRIP)效应显著,力学性能最佳,屈服强度为791.7 MPa、抗拉强度为1041.7 MPa、伸长率为19.37%、强塑积达到20.18 GPa·%。
The static continuous cooling transition curve(CCT curve)of 1.0 GPa cold rolled dual phase steel with high formability was drawn by the combination method of thermal expansion-microstructure-microhardness,and the effect of annealing process on microstructure and mechanical properties of the experimental steel was studied.The results show that the undercooled austenite transformation process of the experimental steel mainly includes three transformation zones:ferrite transformation zone,bainite transformation zone and martensite transformation zone.When the cooling rate is lower than 1℃/s,ferrite and bainite transformation mainly occur in the experimental steel,and there is a small amount of martensite transformation.When the cooling rate is between 3℃/s and 20℃/s,martensite and bainite transformation occurs.When the cooling rate reaches 30℃/s and above,martensitic transformation occurs completely.With the increase of cooling rate,the microhardness of the experimental steel gradually increases,and increases more rapidly in the early stage.After the cooling rate reaches 20℃/s,it gradually tends to be stable,which is consistent with the microstructure at the corresponding cooling rate.The microstructure of the experimental steel is mainly ferrite,martensite and retained austenite.The matching of the three microstructure is beneficial to the improvement of the matrix strength and plasticity during the deformation process.When the soaking temperature is 810℃,the retained austenite content in the experimental steel is the highest,which is 4.9%.During the deformation process,the transformation induced plasticity(TRIP)effect is significant,and the mechanical properties are the best,in which the yield strength is 791.7 MPa,the tensile strength is 1041.7 MPa,the elongation is 19.37%,and the product of strength and plastic is 20.18 GPa·%.
作者
于晓飞
曹晓恩
薛仁杰
赵林林
刘鹏
YU Xiao-fei;CAO Xiao-en;XUE Ren-jie;ZHAO Lin-lin;LIU Peng(Technology Center,HanSteel Company,HBIS Group,Handan 056015,China;School of Materials and Metallurgy,Wuhan University of Science and Technology,Wuhan 430081,China;HBIS Materials Technology Research Institute,HBIS Group,Shijiazhuang 050023,China)
出处
《材料热处理学报》
CAS
CSCD
北大核心
2022年第12期116-124,共9页
Transactions of Materials and Heat Treatment
