Precipitated phases of superaustenitic stainless steel 654SMO

The phase diagram of superaustenitic stainless steel 654SMO was calculated by thermodynamic software and the precipitated phases in the specimens aged at 800 – 1100 °C for 1 h were studied by methods of physicochemical phase analysis, scanning electron microscopy and transmission electron microscopy. The results showed that the size of precipitated particles increased with increasing the temperature. The amount of second phases reached the maximum value at 900 °C, but decreased above 900 °C. There were about eight kinds of precipitated phases in 654SMO including σ phase, Cr₂N, μ phase, χ phase, Laves phase, M₂₃C₆, M₆C and M₃C, in which the σ phase and Cr₂ N were the dominant precipitated phases.