The effect of cold work on structure and properties of AISI 304 stainless steel

This article investigates the effect of various degrees of plastic deformation introduced by cold rolling at ambient temperature on the tensile properties of AISI 304 stainless steel. Microstructural, ferromagnetic and hardness studies were also conducted. The material was evaluated up to 50% reduction in thickness. The results indicate that the formation of strain-induced martensite evidently led to a significant strengthening of the steel. The tensile strength, yield strength and hardness were found to increase with the increase of cold rolling percentage (%CR) up to 45%. It was found that the ratio of tensile strength in MPa to Vickers hardness is constant and is approximately three for all percentages of cold rolling studied. Moreover, the percentage increase of tensile strength from 0% CR to 50% CR was found to be as that of hardness.Plastic deformation between 45% CR and 50% CR was found to have a negligible effect on tensile and yield strengths of the investigated steel. A slight effect on the hardness was noticed after 45% CR. From such results it may be concluded that 304SS has undergone a state of full-hard at this degree of plastic deformation.