Effects of Aluminium on the Microstructure and Mechanical Properties in 0.2C-5Mn Steels under Different Heat Treatment Conditions

The effects of aluminium on mcrostructure and mechanical properties in medium manganese steels were investigated in this study. It is found that addition of aluminium don't significantly change the microstructure evolution during heat treatment process, aluminium can retard the precipitation of carbides in the following annealing, resulting in higher carbon content in several austenite. Though aluminium addition leads to a certain decline of tensile strength, the yield strength and elongation are neither decreasing significantly, especially the former is improved after heat treatment. Furthermore, the Al-bearing medium manganese steels can achieve optimal product of strength and ductility with austenization at 675 degrees C and short time (5 min) annealing, the excellent mechanical properties are strength similar to 880 MPa, total elongation similar to 39.3% and product of tensile strength to total elongation (Rm*A(T)) similar to 34.6 GPa%.