Investigation on Induced Compressive Residual Stress Using the Depth-Sensing Indention Method of SSMT-Processed ETP Copper

This research aims to investigate approximate process parameters in severe surface mechanical treatments, which play a main role in producing good surface quality, inducing residual stress, and less damage to material during surface treatment of materials. The Taguchi orthogonal array and ANOVA are utilized to find the impact of process parameters and their significant contribution. It is observed that shot diameter and speed of revolution of the shaft have a significant effect on surface hardness. The optimum condition, i.e., an 8 mm shot diameter, a 750 rpm speed of revolution, and a 45 min treatment duration, contribute a higher surface hardness of 124 HV confirmed with the predicted value, and the obtained surface hardness is 35% higher than the untreated specimen. Compressive residual stress is calculated using the depth-sensing indention method, which is about 126 MPa for the optimum condition of hardness. The depth of the deformed layer is around 350 μm from the top surface towards the metal core. The nanohardness is improved from 1.311 to 1.464 GPa for the optimum condition which is 10% higher than the unpeened specimen.