An Investigation on Mechanical Properties of Ultrafine Grained 316 Stainless Steel by Thermomechanical Treatment

In this paper, an advanced thermomechanical treatment was conducted on AISI 316 austenitic stainless steel. At first, three samples were rolled at the ambient temperature, the temperature of 20 ºC (dry ice and ethanol) and 196 ºC (liquid nitrogen). Then, the samples were annealed at 800 ºC in the time range of 1 to 15 minutes. In each step, the microhardness values of the samples were measured. Microstructural investigations were conducted using optical and SEM microscopes and Clemex software. Results showed that microhardness of the samples increased due to the formation and precipitation of carbides. The formation of martensitic microstructure after the rolling process was revealed by Xray diffraction analysis; and by decreasing the rolling temperature, the peak intensity increased. Also, by increasing the annealing time in each step, the volume fraction of the reverted austenite and the intensity of the austenite peaks increased.