Effect of heat treatment on precipitation behavior of second phase and property evolution of martensitic stainless steel

The microstructural optimization for 15-5PH stainless steel by heat treatment to enhance toughness and corrosion resistance were investigated. The results indicate that Cu-rich nanoparticles with a size of less than 30 nm are homogeneously dispersed within the matrix, exhibiting a K-S orientation relationship with the martensite matrix during the aging treatment. Additionally, reversed austenite is found to be distributed at the martensite lath boundaries, with the maximum content of 1.62% being observed at 550 °C. With increasing aging temperature, the dispersion strengthening effect caused by the precipitation of Cu-rich phases gradually weakens. After immersion in a 6% FeCl3 solution for 12 hours, the greatest weight loss is observed in the 600 °C treated samples, followed by those treated at 450 °C, 550 °C, and 1050 °C.