Investigating the Effect of Deformation Temperature on the Structure and Mechanical Properties of AISI 304 Stainless Steel

Introduction and targets: AISI 304 austenitic stainless steel is widely recognized for its excellent corrosion resistance and mechanical properties, making it suitable for various industrial applications. However, the presence of non-equilibrium δ-ferrite phase can significantly compromise these properties. This study aims to optimize the hot deformation process to dissolve the residual δ-ferrite in AISI 304 stainless steel by adjusting the deformation temperature and the degree of reduction.Materials and methods: The sheet was hot rolled at temperatures ranging from 1050 °C to 1150 °C. Hot rolling was performed with reductions in cross-sectional area of 30% and 60%. Phase percentage and grain size were analyzed using image analysis software, and the hardness and tensile properties of the hot-rolled samples were examined.Results: Results of image analysis showed that the amount of ferrite in the rolled sample heated at 1150 °C and with a percentage reduction area of 60% reached its lowest level, namely 0.39%. Additionally, with decreasing rolling temperature and increasing the reduction of area, the average grain size became smaller and, as a result, the hardness of the samples increased. As a result, performing hot rolling at a temperature of 1150 °C with a 60% reduction of area led to decrease the grain size to the lowest value of 54.73 µm. The tensile test results also revealed that this sample had the highest yield stress of 345 MPa and the ultimate tensile strength of 653 MPa.Conclusion: The results declared that the best conditions for ferrite removal were rolling at a temperature of 1150 °C with a percentage of cross-sectional area reduction of 60%.