Research on the microstructure and properties of a multi-pass friction stir processed 6061Al coating for AZ31 Mg alloy

A 6061 Al coating for AZ31 Mg alloy was prepared by multi-pass friction stir welding (FSW) with different travel speeds. The microstructure, mechanical properties of the interfacial region and the corrosion behavior of the coating were investigated systematically. The results indicate that the interfacial intermetallic compounds formed in the stir zone (SZ) consist of mainly Al12Mg17 and Al3Mg2. The intermetallic compounds in the SZ are significantly increased when the travel speed is increased from 30 mm/min to 60 mm/min. Microhardness measurements and results of shear-tensile tests show that the mechanical properties are influenced by the intermetallic compounds formed in the SZ during FSW. Corrosion tests indicate that the 6061 Al coating can significantly improve the corrosion resistance of AZ31 plate. The 6061 Al coating obtained with a travel speed of 30 mm/min has a maximum corrosion potential Ecorr of -0.503 VVSE. Keywords: AZ31 alloy, 6061Al alloy, FSW, Microstructure, Properties, Corrosion