Dependence of Grain Size on Mechanical Properties and Microstructures of High Manganese Austenitic Steel

AbstractA high manganese austenitic steel Fe-25Mn-3Cr-3Al-0.3C-0.01N (in wt. pct) with grain sizes 2.2∼28.7μm was obtained by annealing the cold rolled sheet at temperature ranging from 700°C to 1000°C. Dependence of grain size on the mechanical properties and microstructures of this high manganese steel were studied by using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and room temperature tensile test. The results show that, with the increase of grain size from 2.2μm to 28.7μm, the yield and ultimate tensile strengths of this steel were decreased from 410.0MPa to 232.5MPa and 725.0MPa to 517.0MPa, respectively. And the elongation of this steel was accordingly increased from 15.4% to 54.2%. Additionally, deformation twins are easy to form during tensile deformation when the initial grain size is increased