Ti+Nb和Ti+V超低碳烘烤硬化钢的组织和性能研究

Research on Microstructure and Mechanical Properties of Ti+Nb and Ti+V Ultra-low Carbon Bake Hardening Steels

采用Gleeble-1500热模拟试验机对Ti+Nb和Ti+V复合处理超低碳BH钢的变形抗力和动态连续冷却转变进行研究,并观察了两种实验钢在不同冷却工艺条件下的金相组织。结果表明:在1100℃、应变速率1s-1时Ti+Nb超低碳BH钢的变形抗力比Ti+V超低碳BH钢高出约13MPa,在相同的变形条件下,两种实验钢的组织形貌及晶粒尺寸差别较大。两种超低碳BH钢在不同冷却条件下的室温金相组织均是多边形的铁素体,Ti+Nb超低碳BH钢铁素体晶粒较为细小,形状不规则,平均晶粒尺寸为16μm,Ti+V超低碳BH钢铁素体晶粒则较为粗大,形状规则,平均晶粒尺寸为26μm。

Deformation resistance and dynamic continuous cooling transformation of Ti＋Nb and Ti＋V bearing ultra-low carbon bake hardening steels were studied using Gleeble-1500 thermal simulator.The microstructures of two experimental steels under different cooling conditions were also analyzed.The results showed that the deformation resistance of Ti＋Nb bearing ultra-low carbon bake hardening steel was 13MPa higher than that of Ti＋V bearing ultra-low carbon bake hardening steel at 1100℃ with the strain rate of 1s-1.The morphology of the microstructures and the grain size have big difference for two experimental steels under the same deformation conditions.The room temperature microstructures of the two experimental steels are polygonal ferrites under various cooling conditions.The ferrites of Ti＋Nb bearing ultra-low carbon bake hardening steel are finer and have irregular shape with the average grain size of 16μm,while for Ti＋V bearing ultra-low carbon bake hardening steel,the ferrites are coarse and have regular shape with the average grain size of 26μm.