Microstructure thermostability of high nitrogen austenitic stainless steel

Abstract： High nitrogen austenitic stainless steel, Fe24Mn18Cr3Ni0.62N, was isothermal annealed from 750℃ to 900 ℃ for different time to investigate the thermostability of its microstructures. Results show that precipitations were Cr2N and firstly formed along the grain boundary. The time-temperature-precipitation diagram was established, according to which the critical cooling rate of this material with less than 0.1~0.5 vol. % of precipitated Cr2N was specified as 30℃/min. The microhardness of the matrix in samples annealed at different temperatures decreased with the diffusion of nitrogen from the matrix to grain boundaries.