过时效温度对780 MPa级复相钢组织演变及力学性能的影响  

Effects of Overaging Temperature on Microstructure Evolution and Mechanical Properties of 780 MPa Complex-phase Steel

作　　者：徐兵 富聿晶 闵铜 李佳彧 王源 刘宏亮 许云波[1] XU Bing;FU Yujing;MIN Tong;LI Jiayu;WANG Yuan;LIU Hongliang;XU Yunbo(State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang 110819,China)

机构地区：[1]东北大学轧制技术及连轧自动化国家重点实验室,辽宁沈阳110819

出　　处：《热加工工艺》2023年第2期156-160,共5页Hot Working Technology

基　　金：国家重点研发计划项目(2017YFB0304105,2017YFB0304400);国家自然科学基金资助项目(51674080,51974085);山东省重点研发计划项目(2019TSLH0103)。

摘　　要：研究了等温淬火工艺下不同过时效温度对低C含Al微合金钢组织演变及力学性能的影响。结果表明,实验钢在各工艺条件下的显微组织均由临界区铁素体、马氏体、贝氏体和残余奥氏体组成。随着过时效温度的提高,组织中的马氏体含量降低,马奥岛尺寸减小,抗拉强度降低,但伸长率明显提高。XRD分析结果表明,在380℃过时效时,残余奥氏体含量达到8.2%。此外,瞬时加工硬化指数曲线表明,选取较高的过时效温度时,组织中的残余奥氏体能发生持续的TRIP效应,有利于获得良好的强塑性匹配。在380℃过时效时,实验钢获得了优异的综合力学性能,其抗拉强度为787 MPa、伸长率为38.9%、强塑积>30 GPa·%。Based on the austempering process, the effects of overaging temperature on the microstructure evolution and mechanical properties of low carbon micro-alloyed steel with aluminum addition were studied. The results show that the microstructure of test steel with different processes condition consists of intercritical ferrite, martensite, bainite and retained austenite. With the increase of overaging temperature, the fraction of martensite decreases and the grain size of M/A island is refined, resulting in the decrease of strength and significant improvement of total elongation. Based on the result of XRD, the amount of retained austenite is up to 8.2%, when overaging temperature is 380 ℃. Morever, it can be found that the instantaneous work hardening exponent curves of specimen with relatively higher overaging temperature show continuous TRIP effect, which is beneficial to obtain a good combination of strength and ductility. The excellent mechanical properties with tensile strength of 787 MPa, total elongation up to 38.9%, and product of strength and elongation(PSE)above 30 GPa·%is obtained after overaging at 380 ℃.

关 键 词：过时效温度 微观组织 力学性能 残余奥氏体 加工硬化行为 

分 类 号：TG161[金属学及工艺—热处理]