JOINING VACUUM HIGH PRESSURE DIE CAST A356 UNDER T4 TREATMENT TO WROUGHT ALLOY 6061

摘要

Vacuum high pressure die cast A356 alloy with T4 solution treatment was fusion-joined with wrought alloy 6061 by the Gas Metal Arc Welding (GMAW) process. In the present work, the microstructures of Base metal (T4 A356 and 6061), Heat Affected Zone (HAZ) and Fusion Zone (filler metal ER4043) was analyzed by Scanning Electron Microscopy (SEM) and optical microscopy. The results of tensile testing indicate that the ultimate tensile strength (UTS), yield strength (YS) and elongation (Ef) of T4 A356 are relatively low, compared to both wrought alloy 6061 and the filler metal (ER 4043). The microstructure analysis shows that the reduction in the tensile properties of T4 A356 should be mainly attributed to the lack of strengthening intermetallic phases (Mg_2Si) and coarse grain structure, which resulted from T4 solution treatment.