超纯铁素体不锈钢425组织性能研究与评价

Research and evaluation on microstructure and properties of ultra-purified ferritic stainless steel 425

425不锈钢是一种针对汽车排气系统冷端开发的资源节约型超纯铁素体不锈钢,其中铬元素的质量分数为15%,采用铌钛双元素进行碳、氮的稳定化控制。通过光学显微镜、扫描电子显微镜、万能电子试验机以及电化学工作站等,研究880~1000℃退火后425不锈钢显微组织和拉伸性能的演变规律,并与409和439不锈钢进行成形性及耐腐蚀性能的对比研究。结果表明,退火温度为960℃时,425不锈钢具有最佳的显微组织和拉伸性能组合,其成形性能与439、409相当,点腐蚀速率略大于439、明显低于409,点蚀电位介于409和439之间。总体来说,超纯铁素体不锈钢425具有良好的塑性、成形性和耐腐蚀性能,是汽车排气系统冷端应用的理想材料。

425steel is a resource-saving,ultra-purified ferritic stainless steel developed for the cold end of automobile exhaust system.Its chromium mass fraction is 15%,carbon and nitrogen are stabilized using Ti and Nb elements.The microstructure evolution and tensile properties of 425steel after annealing at 880~1000℃were investigated by optical microscope,scanning electron microscope,electro-mechanical universal testing machines and electrochemical workstation,and the formability and corrosion resistance were compared with 409and 439steel.The results show that 425steel has the best combination of microstructure and tensile properties after annealing at 960℃.The formability of 425steel is equivalent to that of 439and 409steel,the pitting corrosion rate is slightly greater than that of 439and significantly lower than that of 409steel,and the pitting potential is between that of 409and 439 steel.In general,425ultra-purified ferritic stainless steel has good plasticity,formability and corrosion resistance.It is an ideal material for cold end application of automobile exhaust system.