Influence of annealing conditions on microstructure and phase occurrence in high-alloy CrMnN steels

The influence of annealing at 750, 800, 850, 900 and 950 °C for 4 h on the microstructure and the phase occurrence in two high-alloy CrMnN austenitic stainless steels was investigated using light microscopy, transmission electron microscopy, and thermodynamic calculations. Austenite, σ, and Cr2N were identified in both steels experimentally. The experimental results were found to be in good agreement with the thermodynamic predictions. In one of the steels, M23C6 as a non-equilibrium probably residual phase was found. Cr2N appeared in the steels either in the form of discrete particles or as a part of cells consisting of alternate lamellae of Cr2N and austenite.