V对含氮马氏体不锈钢组织和力学性能的影响

Effect of vanadium on microstructure and mechanical properties of nitrogen-containing martensitic stainless steel

为提升含氮马氏体不锈钢在高温下服役性能,设计了两种试验钢(一种添加0.12%V(质量分数),一种不加V),采用冲击、拉伸试验机、洛氏硬度计、Thermo-Calc软件、OM、SEM、TEM研究了添加微量的V对含氮马氏体不锈钢组织和力学性能的影响。结果表明,在较高温度450~550℃下回火,添加0.12%V较不加V的含氮马氏体不锈钢硬度提高了0.6~1.9 HRC,冲击吸收能量提高了1.2~3.8 J。1050℃淬火、-73℃冷处理、530℃回火后,添加0.12%V钢的塑韧性得到较大提升,断裂方式改变为韧-脆混合断裂,原奥氏体晶粒尺寸由16.48μm减小为11.12μm,未溶第二相的种类和分布由沿着原奥氏体晶界呈断链状分布的短棒状M23C6碳化物转变为弥散分布的球状碳化物和碳氮化物。通过细化晶粒和均匀分布的球状碳化物、碳氮化物,使得含氮马氏体不锈钢的强度和塑韧性均得到提升。

In order to improve the service performance of nitrogen-containing martensitic stainless steel at high temperature,two tested steels(one with 0.12%V(mass fraction)and one without V)were designed.The effect of adding a trace amount of vanadium on microstructure and mechanical properties of the nitrogen-containing martensitic stainless steel was studied by impact tester,tensile tester,hardness tester,Thermo-Calc software,OM,SEM and TEM.The results show that the hardness of nitrogen bearing martensitic stainless steel with 0.12%V tempered at 450-550℃is 0.6-1.9 HRC higher and the impact absorbed energy is 1.2-3.8 J higher than that without V.After quenching at 1050℃,cryogenic treatment at-73℃and tempering at 530℃,the plasticity and toughness of the 0.12%V steel are greatly improved,the fracture mode changes to ductile-brittle mixed fracture,and the prior austenite grain size decreases from 16.48μm to 11.12μm,the types and distribution of the secondary phases change from the short rod-like coarse carbides distributed as broken chains along the prior austenite grain boundary into dispersively distributed spherical carbides and carbonitrides.Thus the strength and ductility of the nitrogen bearing martensitic stainless steel are all improved by refining grains and uniformly distributing spherical carbides and carbonitrides.