Microstructure and texture evolution in 21Mn-2.5Si-1.6Al-Ti steel subjected to dynamic impact loading

The microstructure and texture evolutions in a microalloyed high Mn austenitic steel during dynamic impact loading was investigated. Microstructural investigations confirmed heterogeneous deformation leading to formation of adiabatic shear band which align parallel to the impact direction. Electron backscatter diffraction analysis indicated the formation of athermal epsilon martensite and ά-martensite within the shear bands. The thermally induced epsilon martensite follows Shoji-Nishiyama crystallographic orientation relationship with parent austenite phase, while ά-martensite shows Burgers relationship with epsilon martensite. The plastic deformation within the austenite phase is characterized by slip and mechanical twinning alongside with martensite formation in regions away from shear bands. The austenite texture outside shear band regions showed characteristic near ID∥〈110〉 orientation (ID: impact direction), whereas the regions inside shear band exhibit both near ID∥〈100〉 and ID∥〈110〉 orientations.