Precipitation Kinetics of Cr2N in High Nitrogen Austenitic Stainless Steel

The precipitation behavior of Cr2N during isothermal aging in the temperature range from 700 °C to 950 °C in Fe-18Cr-12Mn-0.48N (in mass percent) high nitrogen austenitic stainless steel, including morphology and content of precipitate, was investigated using optical microscopy, scanning electron microscopy, and transmission electron microscopy. The isothermal precipitation kinetics curve of Cr2N and the corresponding precipitation activation energy were obtained. The results show that Cr2N phase precipitates in a cellular way and its morphology is transformed from initial granular precipitates to lamellar ones in the cell with increasing aging time. The nose temperature of Cr2N precipitation is about 800 °C, with a corresponding incubation period of 30 min, and the ceiling temperature of Cr2N precipitation is 950 °C. The diffusion activation energy of Cr2N precipitation is 296 kJ/mol.