Experimental study on improving the additively manufactured GMAW and TIG beads using FSP

The beneficial effect of the friction stir processing (FSP) technique for improving the properties of fabricated additive parts through microstructural refinement and repairing of metallurgical defects has shown its ability to be integrated into a hybrid additive manufacturing system. In the present work, conventional GMAW and TIG-based additive manufacturing processes were further post-processed with friction stir process (FSP). In the case of GMAW + friction stir processed (FSP) additive beads, the improvement in mechanical properties in terms of hardness and flexural strength was observed. The enhanced properties were due to refined microstructures obtained through FSP, consisting of polygonal ferrite, islands of martensite-austenite constituents, and lath martensite. While in the TIG + FSP specimen of 6061-T6 AA at 5100 W, backscattered electron and electron probe micro-analyzer images obtained from the stir zone show the presence of fragmented and homogeneously distributed precipitate and intermetallic particles. Also, typical fusion welds defects such as porosities and solidification cracks were repaired. The microstructural refinement helps to improve the fracture strain of the bending specimens.