Fiber laser-MAG hybrid welding of DP/AISI 316 and TWIP/AISI 316 dissimilar weld

In this paper, TWinning-Induced Plasticity (TWIP), Dual Phase (DP) and austenitic stainless (AISI 316) steels were joined together by hybrid laser/arc welding with an austenitic steel filler. Microstructural and mechanical characterization of welded joints was carried out by optical microscopy, microhardness, tensile and bend tests. The heat affected zone (HAZ) at the TWIP side was fully austenitic and exhibited a grain coarsening; at the DP side, new martensite formed close to the fusion zone and other phase transformations occurred moving toward the base metal; at the AISI 316 side, stringers of untreated ferrite δ inside the austenitic matrix was observed. All the tensile welded specimens broke within austenitic stainless steel. TWIP/AISI 316 welds exhibited a greater tensile strength than DP/AISI 316 ones. The bending tests confirmed the ductility of both sorts of joints