Effect of multi-pass friction stir process on the microstructure, corrosion resistance, and mechanical properties of AZ31magnisume alloy

Friction stir processing (FSP) using the multi-pass was introduced as an alternative method to process AZ31 magnesium alloy plates that were 5 mm thick, and the effect of microstructural properties on enhancing corrosion performance and mechanical properties was investigated. The findings indicate after two passes, the average grain size of the as received AZ31 base metal decreased from15µm to around 5 µm, due to a sufficient heat input caused by increasing pass number and dynamic recrystallization (DRX). The evaluations of microhardness revealed that increasing the number of FSP passes resulted in a considerable increase of almost 66%, in 2 pass FSP, obviously improved the corrosion performance of the AZ31 alloy.