Effect of Tool Rotation on Microstructure and Hardness of AZ31 Mg Alloy Processed by FSP

Abstract

The use of magnesium in the automobile and biomedical applications is increasing nowadays due to its lightweight and high specific strength but magnesium alloys have some drawbacks like low ductility, low absolute strength at higher temperature, low hardness, etc. In this research, Friction stir processing (FSP) has been used for improving the hardness and microstructural properties of magnesium AZ31 alloy. The changes in the properties have been observed at different tool rotations (580, 850 and 1160 rpm). It has been found that the size of the grains is maximum for the as-received sample, and its average size lies in between 47 and 69 µm and size of grains is minimum for the FS processed samples at 850 rpm and its average grain size lies in between 0.75 and 1.1 µm. The FS processed samples at 850 rpm showed an approximate 33–37% increase in the hardness.