A comparison between laser and TIG welding of selective laser melted AlSi10Mg

Abstract

A comparison between laser and TIG welding of selective laser melted (SLMed) and cast AlSi10Mg was performed in this paper. The weld morphology, defects, microstructure, and mechanical properties were studied in detail. It is found that compared with the cast AlSi10Mg, SLMed AlSi10Mg has very high pore susceptibility. Pores are the main defect in welding SLMed AlSi10Mg. The large pores distribute at the boundary of the weld for TIG welding, while the large pores distribute at the upper part of the weld for laser welding. The grain size of the weld centre of laser welding is much smaller than that of TIG. At the weld boundary, the TIG welded sample has a larger heat affected zone (HAZ), and the Si in the HAZ is completely transformed into particles and uniformly dispersed in the matrix. However, the HAZ of laser welding is narrow, and the transformation of dendritic Si is incomplete. At the weld centre, the TIG weld presents as coarse equiaxed grains, while the laser weld is all dendrites. For SLMed to SLMed sample welded by TIG, the lowest microhardness appears at weld boundary, where the tensile sample fractures. For SLMed to SLMed sample welded by laser, the lowest microhardness appears at weld centre, where also the tensile sample fractures. For cast to cast sample welded by laser, the microhardness of the weld is higher than that of base metal, and the tensile sample fracture at base metal. However, the elongation of all samples is very poor.