Effect of process parameters on the weld quality in laser welding of AZ31B magnesium alloy in lap joint configuration

Abstract

Magnesium is the lightest structural metal; therefore it has been used in a variety of industries such as automotive, aerospace, electronics and defense. Among different joining processes, laser welding is advantageous due to its low heat input, high depth-to-width weld ratio and good mechanical properties. In this study, a fiber laser is used to weld AZ31B magnesium alloy in a lap joint configuration. Pores were formed in the weld bead that are caused by a thick oxide layer existing on the surface of as-received AZ31B samples. Process parameters including laser power and welding speed are studied to determine their effects on pore formation and maximum lap-shear load of the weld bead. Hardness and tensile tests are carried out to reveal the mechanical properties of the weld bead. A regression analysis is performed that establishes a mathematical relation between the process parameters and the weld maximum lap-shear load. Three regression models are compared in order to determine their accuracy in prediction of the maximum lap-shear load and results revealed that the linear model could best predict the maximum lap-shear load by process parameters.