Effect of Si and Mn on Microstructure and Tensile Properties of Austenitic Stainless Steel

Si and Mn are usually added into austenitic stainless steels to improve their corrosion resistance by improving the oxide film forming ability and increasing the stability of austenite matrix. However, the addition of Si and Mn significantly affects the microstructure and mechanical properties of the cold-worked material. In this study, austenitic stainless steels with different Si and Mn contents were designed. The microstructure of the alloys is characterized by SEM, EPMA, and TEM, and the mechanical properties are evaluated by tensile tests at room temperature. As Si content increases from 1.0wt% to 2.0wt%, the volume fraction of deformation twins increases from 4.98% to 8.33%, the yield strength increases from 620 MPa to 682 MPa, and the elongation basically remains constant; as Mn content increases from 1.5 wt% to 2.0wt%, the volume fraction of the deformation twins decreases from 8.33% to 7.22%, the yield strength decreases from 682 MPa to 627 MPa, and the elongation increases from 16.0% to 21.3%. Si addition increases the quantity of deformation twins in the alloy, improves the strength of the alloy and maintains plasticity; Mn addition reduces the number of the deformation twins in the alloy, reduces the strength of the alloy and enhances plasticity.