Investigation of Crystallographic Orientation and Mechanical Behaviour in Laser-Welded Stainless Steel 316L Additive Components

The main factor limiting the adoption of selective laser melting (SLM)-based additive manufacturing is the smaller build size where mechanical joining methods are inevitable. Besides, there are no standard techniques to rework the defective SLM parts. There are limited test data to delineate the rework ability of defective SLM parts by laser welding route. Based on these facts, weldability studies were performed in the SLM-built stainless steel 316L samples, and the soundness of the weld was evaluated. Results of microstructural characterization revealed that the weld fusion zone was primarily characterized with a mixture of coarser cellular dendrite, columnar dendrite and equiaxed morphologies. Furthermore, crystallographic orientation analysis showed the evolution of random texture across the fusion zone, while the heat-affected zone (HAZ) towards the base metal was observed with a dominant < 001 > texture. Tensile testing revealed that the onset of fracture across the HAZ could be ascribed to the evolution of low Taylor factor grains and a high fraction of low-angle grain boundaries. However, the laser-welded SLM sample exhibited superior tensile strength and hardness of 596 MPa and 271 HV. The findings of this study could open up novel avenues for reworking a wide range of defective SLM components.