Ti微合金淬火钢等温回火过程中组织及硬度变化  

Changes in microstructure and hardness of Ti-microalloyed quenched steel during isothermal tempering process

作　　者：吴林[1] 刘文胜 张可 彭怡楚 曹燕光 张熹 WU Lin;LIU Wen-sheng;ZHANG Ke;PENG Yi-chu;CAO Yan-guang;ZHANG Xi(Central Iron and Steel Research Institute Co Ltd,Beijing 100081,China;School of Metallurgical Engineering,Anhui University of Technology,Ma’anshan 243032,China;Tianjin Bridge Welding Materials Group Co Ltd,Tianjin 300400,China)

机构地区：[1]钢铁研究总院有限公司,北京100081 [2]安徽工业大学冶金工程学院,安徽马鞍山243032 [3]天津大桥焊材集团有限公司,天津300400

出　　处：《材料热处理学报》2023年第11期184-191,共8页Transactions of Materials and Heat Treatment

基　　金：常州市“龙城英才计划”-领军型创新人才引进培育项目(CQ20220003);国家自然科学基金(51704008)。

摘　　要：利用光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)和Vickers硬度计等研究了Ti微合金淬火钢在600℃回火不同时间后的组织、析出相及硬度变化,分析了微观组织和析出相对硬度的影响机理。结果表明:Ti微合金钢经600℃回火0~20 h后,显微组织为回火索氏体。随回火时间的增加,试验钢的硬度总体呈现出先下降后上升再下降的趋势,在回火180 s时达到峰值,为309 HV5,且马氏体板条不断溶解、合并,导致其宽度增加。回火10~180 s时,硬度增加是由于纳米级TiC析出相增多,此时TiC粒子产生的析出强化效果最佳。回火180 s~10 h后,硬度下降的主要原因是马氏体的回复程度加深,且碳化物的沉淀强化效果减弱。回火后期(10~20 h),TiC的析出基本停滞,形貌由球状转变为椭球状,TiC粗化是试验钢硬度加速降低的重要原因。Microstructure,precipitated phases and hardness changes of Ti-microalloyed quenched steel after tempering at 600℃for different time were studied by means of optical microscope(OM),scanning electron microscopy(SEM),transmission electron microscopy(TEM)and Vickers hardness tester.The influence mechanism of microstructure and precipitated phases on hardness was analyzed.The results show that after tempering at 600℃for 0-20 h,the microstructure of the Ti-microalloyed steel is tempered sorbite.The hardness of the experimental steel generally shows a trend of first decreasing,then increasing and then decreasing with the increase of tempering time,reaching a peak value of 309 HV5 after tempering for 180 s,and the martensite laths are continuously dissolved and coarsen,resulting in an increase in their width.When tempering for 10-180 s,the increase in hardness is due to the increase of nanoscale TiC precipitates,and the precipitation strengthening effect generated by TiC particles is the best at this time.After tempering for 180 s-10 h,the main reason for the decrease of hardness is that the recovery degree of martensite is enhanced,and the precipitation strengthening effect of carbide is weakened.In the later stage of tempering(10-20 h),the precipitation of TiC basically stops,and its morphology changes from spherical to ellipsoidal.The coarsening of TiC is an important reason for the accelerated decrease in the hardness of the experimental steel.

关 键 词：钛微合金钢 回火时间 硬度 显微组织 回火索氏体 

分 类 号：TG142.1[一般工业技术—材料科学与工程]