Precipitation during aging in N-containing austenitic stainless steels

Two different N-containing austenitic stainless steels were aged at temperatures from 600 to 800 °C for 10 to 1000 min in order to study the precipitation kinetics. In general, the fastest precipitation occurred in the aged steel with higher content of interstitial solutes, named 24Cr–15Ni–4Mn–0.32N–0.04C steel. Time-temperature-precipitation, TTP, diagrams showed that the intergranular precipitation of M 23C 6 and M 2N preceded to the intragranular precipitation of M 2N and M 2N and η phase in the aged 24Cr–15Ni–4Mn–0.32N–0.04C and 12Cr–12Ni–10Mn–5Mo–0.24N–0.02C steels, respectively. Besides, the presence of cellular precipitation of austenite and M 2N was observed to occur in the aged 24Cr–15Ni–4Mn–0.32N–0.04C steel.