回火时间对BS960E钢快速加热淬火后组织与性能的影响  

Effect of tempering time on microstructure and properties of BS960E steel after rapid heating and quenching

作　　者：马瑞杰[1] 许立雄 周云根[1] 金东浩 MA Rui-jie;XU Li-xiong;ZHOU Yun-gen;JIN Dong-hao(South China Metallurgical Engineering Technology,Wuhan 430200,China;Collaborative Innovation Center of Steel Technology,University of Science&Technology Beijing,Beijing 100089,China)

机构地区：[1]中冶南方工程技术有限公司,湖北武汉430200 [2]北京科技大学钢铁共性技术协同创新中心,北京100089

出　　处：《材料热处理学报》2024年第4期130-139,共10页Transactions of Materials and Heat Treatment

摘　　要：采用光学显微镜、扫描电镜、电子背散射衍射、能谱仪和X射线衍射等研究了回火时间对BS960E钢快速加热淬火后组织与性能的影响。结果表明:BS960E钢淬火后组织为板条状马氏体,其原始奥氏体平均晶粒尺寸为5.69μm,位错密度为4.02281×10^(15)cm^(-2)。随着回火时间的延长,马氏体板条结构逐渐分解;回火2 min时仍存在部分板条组织,有效晶粒尺寸(马氏体板条块)为2.47μm,位错密度急剧下降至9.48079×10^(14)cm^(-2);回火15和30 min时马氏体板条开始粗化,小角度晶界密度占比降低,此时有效晶粒尺寸分别为2.57和2.59μm,位错密度分别为7.80957×10^(14)和6.75406×10^(14)cm^(-2);回火60 min时,马氏体板条块合并明显,大角度晶界密度及占比下降,有效晶粒尺寸粗化达到2.99μm,位错密度降低至5.19655×10^(14)cm^(-2)。碳化物的析出位置可分为原始奥氏体晶界析出、马氏体板条块界析出和晶内析出3类。随着回火时间的延长,BS960E钢的抗拉强度和屈服强度逐渐减小,伸长率增加。回火时间达到60 min时由于析出的碳化物粗大导致伸长率降低。综合考虑BS960E钢经过快速加热淬火后,回火时间在2 min时综合力学性能最佳。Effect of tempering time on microstructure and properties of BS960E steel after rapid heating and quenching was studied by means of optical microscope,scanning electron microscopy,electron backscatter diffraction technique,energy dispersive spectroscopy analysis and X-ray diffraction.The results show that the microstructure of the BS960E steel after quenching is lath martensite,the average grain size of prior austenite is 5.69μm,and the dislocation density is 4.02281×10^(15) cm^(-2).With the increase of tempering time,the martensitic lath structure gradually decomposes,some lath structures still exist after tempering for 2 min,the effective grain size(martensite lath block)is 2.47μm,and the dislocation density sharply decreases to 9.48079×10^(14) cm^(-2).When tempering for 15 and 30 min,the martensite lath begins to coarsen,and the proportion of small angle grain boundary density decreases.At this time,the effective grain sizes are 2.57 and 2.59μm,respectively,and the dislocation densities are 7.80957×10^(14) and 6.75406×10^(14) cm^(-2),respectively.When tempering for 60 min,martensite lath and block merge obviously,the density and proportion of large angle grain boundaries decrease,the effective grain size increases to 2.99μm,and the dislocation density decreases to 5.19655×10^(14) cm^(-2).The precipitation of carbides can be divided into three types:prior austenite grain boundary precipitation,martensite lath block boundary precipitation and intragranular precipitation.With the increase of tempering time,the tensile strength and yield strength of the BS960E steel gradually decrease,while the elongation increases.When the tempering time reaches 60 min,the coarse precipitated carbides lead to a decrease in the elongation.Taking into account the comprehensive mechanical properties of the BS960E steel after rapid heating and quenching,the optimal tempering time is 2 min.

关 键 词：BS960E钢 回火时间 有效晶粒尺寸 位错密度 力学性能 

分 类 号：TG142.3[一般工业技术—材料科学与工程]