Effects of Heat Treatment and Nitrogen on Microstructure and Mechanical Properties of 1Cr12NiMo Martensitic Stainless Steel

A series of heat treatments using the orthogonal experiment method were performed to study the microstructure and mechanical properties of 1Cr12NiMo martensitic stainless steel containing various nitrogen content addition. The results indicate that the optimal heat treatment is annealing at 830 °C for 1 h, austenitizing at 985 °C for 1 h followed by oil quenching, and tempering at 630 °C for 4 h followed by air cooling. Nitrogen addition to 1Cr12NiMo steel can effectively hinder the austenite grain growth, refine the martensite lath, and increase the strength and hardness. The impact toughness of this steel only shows a minor decrease as the nitrogen content increases.