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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。
Pitting corrosion resistance of 15-5PH martensitic precipitation hardened stainless steel was studied by means of chemical immersion, polarization curve, cyclic polarization curve and electrochemical impedance spectroscopy (TEM) X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis of the microstructure and precipitation phase. The results show that as the solution temperature increases, the self-corrosion potential of 15-5PH stainless steel decreases, the corrosion current and corrosion rate increase, and the pitting corrosion resistance decreases. The matrix microstructures aged at different temperatures after solution treatment were lath martensite and a small amount of austenite, and all had NbC phase precipitation. After aging at 1000 ℃, the microstructure of the microstructure is more uniform, with less precipitation and excellent pitting corrosion resistance. After the solution at 1070 ℃, Cu precipitates in the aged microstructure, which leads to the decrease of pitting corrosion resistance.