Effects of Silicon on the Microstructure and Mechanical Properties of 15–15Ti Stainless Steel

Abstract

Effects of silicon on the microstructure and mechanical properties of 20% cold-worked 15–15Ti austenitic stainless steels are systemically investigated by uniaxial tensile tests, scanning and transmission electron microscope observations, and strength calculations. The results reveal that a large number of deformation twins are formed in the 20% cold-worked steels with various silicon additions. The volume fraction of deformation twins and the density of dislocations increase with silicon content, while the twin thickness slightly decreases. A better strength–ductility combination is achieved by silicon addition, since the yield strength of the steel with 2% silicon is 61 MPa higher than that of the steel with 1% silicon, while their uniform elongations are almost both equal to 16%. The yield strength of the 15–15Ti stainless steels is predominantly contributed by the solid solution, dislocation and deformation twin strengthening effects, which can be enhanced by silicon addition.