Microstructure and mechanical properties in laser brazing of A5052/AZ31 dissimilar alloys

Abstract

This investigation into the microstructure and mechanical properties of a joint produced by laser brazing between A5052 and AZ31 with AZ125 filler wire reveals that an increase in laser power from 480 to 620 W reduces the weld toe angle and increases the bead width, resulting in an enhanced wettability. Any further increase in power, however, results in a rapid increase in the thickness of the intermetallic compound (IMC) reaction layer. The IMC layer consists of Mg17Al12 on the AZ125 side and Mg2Al3 on the A5052 side. The tensile shear strength is increased by using a laser power of 480–600 W owing to the increased wettability, but is reduced when using a laser power of 610–620 W owing to the thickness of the reaction layer and the presence of voids, which cause brittle fracture through the brazed filler metal.