Microstructure and mechanical properties of laser welded austenitic high manganese steels

The microstructure of laser welded austenitic twinning induced plasticity steel sheets joints was investigated by means of optical microscopy, SEM and electron backscattering diffraction in order to differentiate the fusion zone, heat affected zone and base material, as well as to establish present phases, grain size distribution and grain misorientation distribution caused by the welding process. Measurements of EDX were taken into account to evaluate the effect of Mn segregations. Microhardness measurements and tensile tests were performed to evaluate the mechanical properties of the joints. In addition, the twinning phenomena progress was assessed by investigating the texture evolution in the base material and fusion zone of samples plastically deformed by 5, 10 and 15%. Grain refinement was found in the fusion zone affecting substantially the mechanical properties of the welding, being the most resistant and harder region.