Hybrid Welding Process(FSW+TIG)을 이용한 이종재료(AZ31B/SS400)의 Tool Plunge Point에 따른 용접부의 열적 특성 해석

Abstract

In this study, it is intended to investigate the weldability and mechanical characteristics of hybrid welding process(TIG+FSW) for dissimilar materials Mg alloy(AZ31B) and Mild Steel(SS400). From the results, the tensile strength of FSW dissimilar joint is found to be lower than that of hybrid welding process(TIG+FSW) at optimum welding conditions. Due to increase in plastic flow and formation of finer recrystallized grains at the TMAZ and SZ by TIG preheating in hybrid welding process(TIG+FSW), the hardness values are more in hybrid welding process(TIG+FSW) compared to FSW. From the microstructure analysis, smaller grain size is observed and parent metal elongated grains are deformed in same direction around the nugget zone in TMAZ of AZ31B by hybrid welding process(TIG+FSW) compared to FSW. At nugget zone, coarse grain size is appeared in hybrid welding process(TIG+FSW) when compared to FSW because of more plastic flow due to laser preheating effect. Refined ferrite-bainite microstructure is formed at weld nugget of SS400. But more brittle fracture is found in FSW welded specimens. In hybrid welding process(TIG+FSW) dissimilar joint ductile mode of fracture is found to occur at AZ31B side with fewer brittle particles. Mixed mode of cleavage area and ductile fracture was observed at SS400 side.