The present work is focused on studying the effect of multiple forging at room temperature and subsequent annealing on the microstructure and mechanical properties of a promising austenitic stainless steel with increased nitrogen content. An austenitic stainless steel, Fe-0.03C-22Cr-10Ni-0.36N-6.2Mn-0.34Si-1.9Mo (all in wt%), with an average grain size of about 11 μm was used as the initial material in the present study. The multiple forging was carried out by means of multi-pass compressions at room temperature to a total true strain of 2. The multiple forging was accompanied by deformation twinning and resulted in significant strengthening. Upon reaching the total strain of 2, the yield strength increased by 690 MPa, and the hardness increased by 210 HV. The steel samples subjected to multiple forging to a total strain of 2 were annealed for 30 minutes at temperatures of 773, 873 and 973 K. Annealing at temperatures of 773 and 873 K resulted in further strengthening, i.e., the yield strength increased to 1990 MPa and 1940 MPa, the hardness increased to 614 HV and 588 HV, respectively. Annealing at a temperature of 973 K led to the formation of an equiaxial ultrafine-grained microstructure and a decrease in the yield strength and hardness to 1300 MPa and 407 HV, respectively. The microstructural evolution during multiple forging and subsequent annealing and the structure-property relationship are discussed in some detail.Keywords: Forging, stainless steel, properties, microstructure
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