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在实验室模拟了含铌与无铌TRIP钢的连续退火工艺过程,通过金相显微技术(OM)、扫描电镜(SEM)、透射电镜(TEM)、背散射电子衍射技术(EBSD)、X射线衍射(XRD)和拉伸实验等检测手段研究了TRIP钢的组织性能,分析了TRIP钢中残余奥氏体稳定性的影响因素及强化机理.结果表明:在连续退火工艺条件下,Nb的存在细化了TRIP钢的微观组织,与未添加Nb的钢相比,添加Nb可以提高TRIP钢中残余奥氏体含量和残余奥氏体碳含量.含铌TRIP钢中残余奥氏体主要以团块状或薄膜状分布于铁素体与贝氏体晶界,极少部分以细小球状分布于铁素体晶内.含铌TRIP钢热轧后的主要析出物为Fe3C和(Nb,Ti)(C,N),退火后的主要析出物为(Nb,Ti)(C,N).细小含铌析出物的析出强化导致了随着退火温度的升高,屈服强度和抗拉强度升高.
The continuous annealing process of niobium-containing and niobium-free TRIP steels was simulated in the laboratory. The microstructures of niobium-free and niobium-free TRIP steels were characterized by OM, SEM, TEM, EBSD, (XRD) and tensile test were used to study the microstructure and mechanical properties of TRIP steel.The influence factors and strengthening mechanism of retained austenite in TRIP steel were analyzed.The results show that the existence of Nb is fine under continuous annealing process The microstructure of TRIP steel is compared with that of Nb-free steel, Nb addition can increase the residual austenite content and residual austenite carbon content in TRIP steel.The residual austenite in the TRIP steel containing niobium mainly consists of clumps Like or thin film distributed in the ferrite and bainite grain boundaries, a small part of the small spherical distribution in the ferrite crystal.Niobium-containing TRIP steel after hot-rolled main precipitates Fe3C and (Nb, Ti) ( (Nb, Ti) (C, N) .The precipitation strengthening of the niobium-containing precipitates resulted in the increase of the yield strength and the tensile strength with the increase of the annealing temperature.