固溶温度对15-5PH不锈钢耐点蚀性能的影响

用化学浸泡、极化曲线、循环极化曲线和电化学阻抗谱等方法研究了不同温度固溶后直接时效状态的15-5PH马氏体沉淀硬化不锈钢的耐点蚀性能,并用金相显微镜、x射线衍射仪(XRD)和扫描电子显微镜(SEM)分析其显微组织和析出相。结果表明,15-5PH不锈钢随着固溶温度的升高,自腐蚀电位减小,自腐蚀电流和腐蚀速率增大,耐点蚀性能下降。不同温度固溶后时效的基体组织均为板条马氏体和少量奥氏体,且均有NbC相析出。在1000℃下固溶后时效组织较均匀,析出相少,耐点蚀性能优异。在1070℃下固溶后时效组织中有Cu析出,进而导致其耐点蚀性能下降。

EFFECTS OF SOLID SOLUTION TEMPERATURE ON PITTING CORROSION BEHAVIOR OF 15-5PH PRECIPITATION HARDENED STAINLESS STEEL

The pitting corrosion resistance property of 15-5PH martensite precipitation hardened stainless steel with direct aging treatment after different solution temperature was investigated by immersion test,polarization curves,cyclic polarization curves and electrochemical spectroscopy.The microstructure and phases precipitated was studied by optical metallography,X-ray diffract ion(XRD) and scanning electron microscopy(SEM).The results show that with the solution temperature ascending,the self-corrosion potential became negative,the self-corrosion current and the corrosion rate increased but the pitting corrosion resistance property was decreased. The microstructure of aging treatment after different solution temperature was lath martensite and a few austenite.The NbC carbide were observed in the specimen quenched and aged at 550℃for 4 h.The homogeneity of the microstructure and less precipitates solution treatment at 1000℃had the best pitting corrosion resistance.When solution treatment at 1070℃the Cu-rich precipitates distributed,but Cu precipitation led to the declination of pitting corrosion resistance.