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对15-5PH不锈钢经不同温度时效后的结构及耐蚀性进行研究。利用金相显微镜、XRD、SEM及TEM观察其组织并对相结构进行分析;采用化学浸泡、极化曲线和电化学阻抗谱等方法研究其耐蚀性能。结果表明:随时效温度的增加马氏体组织逐渐细化,马氏体板条间析出NbC颗粒;当时效温度达到550℃时有球状富Cu相析出。580℃开始有较弱的奥氏体衍射峰出现,即在时效中发生了马氏体向奥氏体的逆转变,620℃时,富Cu相由共格相转变为非共格相并聚集长大呈短棒状;随着时效温度的升高,腐蚀失重率逐渐增大,自腐蚀电位依次降低,电化学阻抗值不断减小,耐蚀性降低。
The structure and corrosion resistance of 15-5PH stainless steel after aging at different temperatures were studied. The microstructure was observed by optical microscope, XRD, SEM and TEM, and the phase structure was analyzed. The chemical corrosion resistance was studied by chemical immersion, polarization curve and electrochemical impedance spectroscopy. The results show that the microstructure of martensite is refined with the increase of aging temperature and the NbC particles are precipitated in the martensite laths. When the aging temperature reaches 550 ℃, the spheroidal Cu-rich phase precipitates. The weak austenite diffraction peak appeared at 580 ℃, that is, the martensitic transformation to austenite took place in aging. At 620 ℃, the Cu-rich phase transformed from coherent phase to non-coherent phase and aggregated As the aging temperature increases, the rate of corrosion weight loss gradually increases, the corrosion potential decreases in turn, the electrochemical impedance decreases, and the corrosion resistance decreases.