Effects of Shot Peening Angle and Time on Microstructure and Wear Behavior of AZ31 Alloy

This study evaluated the effects of peening angle and time on the microstructure and wear behavior of AZ31 alloy subjected to the shot peening process. The samples were shot peened at 30° and 45° for 20 and 80 min with steel pellets. The microstructures and grain sizes of the shot peened samples were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD). In addition, the samples were characterized through hardness and wear measurements. The results showed that shot peening time had a greater effect on grain refining than shot peening angle. In addition, the hardness was increased to 206% for the sample shot peened at 45° for 80 min. This can be ascribed to reduced grain sizes on the surface (crystallite size of 169 Å) and increased micro-strains. The wear test revealed that the wear resistance of the sample was increased with increasing the peening angle and time. Furthermore, the mechanisms of adhesive and abrasive wear were observed for untreated and shot-peened specimens.