回火工艺对铌钛低碳贝氏体钢组织与性能的影响  

Effects of tempering process on microstructure and mechanical properties of Nb-Ti microalloying low-carbon bainite steel

作　　者：李德发[1,2] 王世森[2] 熊玉彰[2] 邢淑清[1] 熊涛[2] 余宏伟[2] 

机构地区：[1]内蒙古科技大学材料与冶金学院,内蒙古包头014010 [2]武汉钢铁(集团)公司研究院,湖北武汉430080

出　　处：《金属热处理》2013年第7期32-36,共5页Heat Treatment of Metals

基　　金：内蒙古自然科学基金(2009MS0811)

摘　　要：通过光学显微镜、透射电镜和力学性能检验,研究了回火温度对TMCP型铌钛微合金化低碳贝氏体钢微观组织结构、第二相析出及力学性能的影响。结果表明,回火后力学性能非单调变化,归因于铌钛微合金化钢在回火过程中,贝氏体内位错亚结构回复软化与第二相析出强化及碳的脱溶机制综合作用。400～500℃回火,Nb、Ti第二相持续析出强化,随回火温度的升高,板条贝氏体回复作用逐渐加强并逐渐达到回复稳定状态。回火温度≥500℃时,M/A岛组织发生分解,贝氏体板条合并、组织粗化,析出相聚集长大,固溶元素脱溶,组织演变为贝氏体和铁素体,强度持续降低,但韧塑性得到改善。550℃回火后钢板具有最佳综合力学性能:抗拉强度为790 MPa,屈服强度为740 MPa,伸长率为16.5%,-20℃冲击吸收能量为250 J。Effects of tempering temperature on microstructure, precipitation and mechanical properties of Nb-Ti microalloyed low-carbon bainite steel produced by TMCP, were researched by optical microscope, TEM and mechanical properties test. The results show that mechanical properties change in non-monotonic, which is ascribed to the comprehensive effect of recovery of dislocation, precipitation strengthening of second phase and dissolution of carbon. Strengthening of precipitation continually takes place when tempering temperature is from 400 ℃to 500 ℃. Recovery effect in bainite is strengthened gradually, and then getting balance. When the tempering temperature is more than 500 ℃, the decomposition of M/A island, merging of lath bainite, roughing of microstructnre, aggregation of the precipitation, dissolution of solid solution elements, microstructure transforming into ferrite and hainite and gradually decreasing of strength, improving of ductility and plasticity are taken place. When the tempering temperature reaches 550 ℃, the best comprehensive mechanical properties of the tested steel are achieved, tensile strength reaches 790 MPa, yield strength 740 MPa, elongation 16.5% and impact energy at -20 ℃ reaches 250 J.

关 键 词：铌钛微合金化钢 回火工艺 贝氏体钢 析出强化 M A岛 

分 类 号：TG335.5[金属学及工艺—金属压力加工]