Influence of ECAP Parameters on Hardness and Grain Refinement in Copper Alloy: Experimental Validation and RSM-Based Optimization

Equal Channel Angular Pressing (ECAP) is a prominent Severe Plastic Deformation (SPD) technique employed to enhance the mechanical and microstructural properties of FCC alloys. In this study, a statistical model was developed to investigate the influence of key processing parameters-die channel angle, number of ECAP passes, and processing temperature on material responses such as Vickers hardness (indicative of mechanical strength) and average grain size (reflective of microstructural evolution). Vickers hardness measurements were conducted pre- and post-deformation using a standardized hardness tester, while optical microscopy was employed to assess the grain structure before and after ECAP processing. The observed correlation between increased hardness and grain refinement supported the Hall-Petch relationship, thereby validating the theoretical basis for strength enhancement through grain boundary strengthening. A response surface methodology (RSM)-based ANOVA model was established using Design Expert software to identify optimal processing conditions for achieving the desired mechanical and microstructural properties. A confirmatory experiment was performed to evaluate the predictive accuracy of the developed model. The optimized copper alloy produced via this process demonstrates potential for applications in the marine and automotive sector.