The fine grained structures of nickel-free high nitrogen austenitic stainless steels had been obtained by means of cold rolling and subsequent annealing.The relationship between microstructure and mechanical properties and gain size of nickel-free high nitrogen austenitic stainless steels was examined.High strength and good ductility of the steel were found.In the grain size range,the Hall-Petch dependency for yield stress,tensile strength,and hard- ness was valid for grain size ranges for the nickel-free high nitrogen austenitic stainless steel.In the present study, the ductility of cold rolled nickel-free high nitrogen austenitic stainless steel decreased with annealing time when the grain size was refined.The fracture surfaces of the tensile specimens in the grain size range were covered with dim- ples as usually seen in a ductile fracture mode. The fine grained structures of nickel-free high nitrogen austenitic stainless steels had been obtained by means of cold rolling and subsequent annealing. The relationship between microstructure and mechanical properties and gain size of nickel-free high nitrogen austenitic stainless steels was examined. High strength and good ductility of the steel were found. In the grain size range, the Hall-Petch dependency for yield stress, tensile strength, and hard-ness was valid for grain size ranges for the nickel-free high nitrogen austenitic stainless steel.In the present study, the ductility of cold rolled nickel-free high nitrogen austenitic stainless steel decreased with annealing time when the grain size was refined. fracture of the tensile specimens in the grain size range were covered with dim- ples as usually seen in a ductile fracture mode.