Abstract: Mechanical properties and the precipitation evolution of second phase of high manganese high aluminum lightweight steels as-cast and solution treated with different aluminum contents (10%, 12%, 14%, mass fraction) were investigated by using methods such as phase analysis, microstructural characterization and room temperature tensile and hardness tests. The results show that under as-cast state, with the increase of Al content, the content of ferrite in the tested steels increases and precipitating discontinuously between austenite grains, the size of κ-carbides continuously increases and mainly precipitating within austenite grains. After solution treatment at 1100 ℃, the tested steels exhibit improved strength and plasticity. The tested steel with 12% aluminum obtains excellent comprehensive properties, of which the density is 6.41 g·cm^-3, the specific strength is 157 MPa·cm³·g^-1, the elongation after fracture is 26.2%.

Key words: high manganese high aluminum lightweight steel, Al content, solution treatment, κ-carbide, mechanical properties