Optimization of the shot peening process parameters to improve the flexural strength of heated 2024 aluminium alloy

The flexural strength of AA2024 aluminium alloy is investigated in this paper when it is heated and shot peened using steel shots. The flexural strength of the materials can be increased by sealing the micro cracks present in the surface of the material. The micro cracks are sealed by shot peening (SP) the material using spherical shots. The residual compressive stress (RCS) imparted by SP on the material surface helps to enhance the fatigue as well as flexural strength. SP is carried out by bombarding the base metal using spherical shaped shots blown using compressed air. In this research, the pressure range is set in the range of 4–8 MPa and the peening distance from the sample and to the nozzle is set in the range of 40–80 mm based on the previous literature. The experiments are designed using response surface method (RSM).Initially, the flexural strength of AA2024 is measured before SP without heating the base metal. SP experiments are conducted based on different combinations of pressure and distance, after heating the specimen to 300 °C for a period of 30 min. The flexural strength of the combinations is determined and the optimum combination of pressure and temperature is identified. Confirmation experiments are conducted and the results are compared with the unpeened and non-heated specimen. It is confirmed that the flexural strength of heated and shot peened AA2024 specimen improved by 12.83% than the unpeened specimen.