Effect of solution heat-treated conditions on structure and mechanical properties of high-manganese steel

The high-Mn austenitic steel containing 0.054% C, 24.4% Mn, 3.5% Si, 1.6% Al, 0.0039% N, 0.029% niobium and 0.075% titanium was investigated in the work. The steel was solution heat-treated at different temperatures in a range from 900°C to 1200°C. The microstructure was characterized by light microscopy and scanning electron microscope. The average diameter of austenite grains increased from approx. 14 μm at the solution annealing temperature of 900°C to about 230 μm – for the solution annealing temperature equal 1200°C. The mechanical properties are a compromise between intensity of mechanical twinning and the grain size. It was shown that the solution annealing temperature affects significantly the grain size and strain hardening behavior of the investigated high-Mn steel with Nb and Ti microadditions.