Corrosion resistance of friction stir processed AZ91D magnesium alloy under a salt fog environment

摘要

Magnesium alloys are widely used in applications where weight reduction is of primary importance. MgAZ91D is an Mg-Al-Zn alloy and its application in the automotive sector is limited by its poor corrosion resistance. Recent advances in solid state processing techniques have made it easier to modify the mechanical and corrosion characteristics of various alloys. Friction stir processing (FSP) is such a solid-state process for surface and sub-surface modification, which increases the microstructural densification, thereby producing fine and equiaxed grains. Through this work, an attempt was made to analyse the effect of friction stir processing on the corrosion resistance of the alloy in an enclosed salt spray chamber. Micro-analysis tools like FESEM and EDS are used to supplement our results. It is seen that, FSP significantly contributes to the increase in the corrosion resistance by homogenising the distribution of α and β phases and hence making the use of the alloy more practical in moisture rich environments.