Microstructure of laser-TIG hybrid welding joint of dissimilar metals of Al and Mg

TIG and laser-TIG hybrid welding techniques have been used to study the weldability of dissimilar alloys of Al-6061 to Mg-AZ31B. The welded samples were analyzed by metallographic techniques using both optical and scanning microscopy in combination with a X-ray diffraction instrument. It was found that the TIG welding could not make the joint of the dissimilar alloys due to the continuous Mg and Al intermetallic compounds. But the laser-TIG hybrid welding improved the weldability because of its high welding speed and fast stir by laser and arc which make the continuous intermetallic compounds on the interface of Mg and changed into dispersive form. The weld appearance of laser-TIG hybrid welding is uniform.