热处理工艺对800MPa低碳贝氏体钢组织性能的影响  

Effect of Heat Treatment on Microstructure and Mechanical Properties of 800 MPa Grade Low Carbon Bainitic Steel

作　　者：左龙飞[1] 魏战雷[1] 倪睿[1] 王自东[1] 陈晓华[2] 

机构地区：[1]北京科技大学材料科学与工程学院,北京100083 [2]北京科技大学大学新金属材料国家重点实验室,北京100083

出　　处：《钢铁研究学报》2012年第12期37-41,共5页Journal of Iron and Steel Research

基　　金：教育部博士点基金(20100006110026)

摘　　要：研究了在不同热处理工艺条件下,一种800MPa级低碳贝氏体钢组织性能的变化规律。通过对控轧控冷(TMCP)、TMCP+水淬(WQ)、TMCP+WQ+回火(T)工艺的比较,发现试验钢在450℃时回火2h后,可以获得具有良好强韧性的组织,屈服强度为816MPa,伸长率大于16%。通过SEM和TEM观察可知,这种钢的室温组织主要是细小的板条状贝氏体、(准)多边形铁素体和少量过冷奥氏体转变相的复相组织,随着回火温度的升高,板条逐渐合并变宽,最终发生多边形化;基体内存在大量的位错以及细小、弥散分布的纳米级第二相粒子,其尺寸约为10～20nm,选区衍射花样标定确定是Nb、Ti的碳氮化物,纳米级第二相粒子与位错的相互作用对材料增强增韧起重要作用,450℃回火时因析出强化造成的强度增量约为233MPa。The effects of thermal treatment on microstructure and mechanical properties of 800 MPa grade low carbon bainitic steels were investigated.After applying thermomechanical control process,water quenching and tempering at different temperatures,optimal comprehensive mechanical properties were obtained when tempered at 450 ℃.The yield strength achieves 816 MPa,simultaneously the elongation exceeds 16%.The morphology by SEM shows that the microstructure consists of fine lath-shape bainite,polygonal ferrite,quasi-polygonal ferrite and a small fraction of residual austenite or martensite-austenite constituents.A TEM study shows that plenty of Nb/Ti carbonitride precipitates with the size about 10-20 nm interacted with the existent dislocations,which is very significant for the improvement of strength and ductility.The strength increment caused by precipitation strenghthening can reach about 233 MPa,when the specimen tempered at 450 ℃.

关 键 词：热处理工艺 低碳贝氏体钢 纳米析出 

分 类 号：TG161[金属学及工艺—热处理]