Enhancing the fatigue strength of stir-casted Al7075-SiC composites through heat treatment and shot peening

Abstract An attempt has been made in the present study to analyze the impact of shot peening on the fatigue strength of Al-SiC (8 wt%) composites. Composite samples prepared using stir casting method is machined to meet ASTM E466 standards, and a portion of them are subjected to T6 heat treatments. Shot peening is performed on various combinations of specimens, and fatigue tests are conducted and compared. The fatigue strength of Al7075 is 156.5 MPa and it increases to 165.8 MPa for heat-treated shot-peened Al-SiC composites. Design expert software is used for designing experiments in order to optimize process parameters and enhance the fatigue strength of the specimens. The fatigue strength of the specimens increased to 174 MPa when the test was repeated using optimized experimental parameters. The fatigue test results revealed that the heat-treated, cum shot-peened Al-SiC composite exhibited the highest performance compared to the other samples. Surface residual stress of the specimens is measured, and it is found that shot peening increases the compressive residual stress on the surface of the specimen. The surface roughness of the specimen increases with shot peening. Microstructural analysis is conducted on the specimens to determine the effect of shot peening on the surface of the composite specimens. The strengthening mechanisms of the composite samples are discussed using microstructural images.