Mechanical and Corrosion Study of Dissimilar Friction Stir Welding of AZ31Mg Alloy and Cu-8Zn Alloy

Fusion welding techniques are not very viable for joining dissimilar metals like copper (Cu) and Magnesium (Mg) alloys, which finds applications in electronics and mobility industries. Basically, numerous researchers have explored Mg alloy and pure Cu joints. But very limited literature is available regarding joining of Mg alloy and Cu alloys. Further, corrosion behaviour of these joints needs to be explored. The present work focuses on friction stir welding (solid state welding) of Cu-8Zn alloy and AZ31 Mg alloy. The main process parameters taken for the work are tool rpm of 1200 and 20 mm/min as travel speed. The resultant weld specimens were examined for microstructural characterization, and for mechanical and corrosion behaviour. The optical microscopy and SEM-EDS analysis revealed that stir zone is made up of complex microstructure. The XRD analysis confirms that the stir zone consists of inter-metallic compounds (IMCs) like Mg2Cu and MgCu2. The potentiodynamic polarization test were conducted and it was found that welded samples have less corrosion resistance than the two parent metals. The micro-hardness of the stir zone reached a maximum value of 429.95 HV because of the existence of IMCs and fine grains. The maximum tensile strength achieved was 68 MPa, with fracture occurred in brittle manner.