Optimization of ECAP parameters of ZX30 alloy using feature engineering assisted machine learning and response surface approaches

Abstract

The precise control of equal channel angular pressing (ECAP) deformation parameters is crucial for producing ultrafine grains in structural ZX30-Mg alloy biodegradable components. To address this challenge, this study aims to conduct a comprehensive analysis of the effects of various ECAP parameters on the microstructure, corrosion, and mechanical properties of ZX30 alloy. ZX30 was utilized through a maximum of 4 passes along routes A, Bc, and C, using die angles of 90ᵒ and 120ᵒ, by utilizing machine learning (ML), artificial neural networks (ANNW), response surface methodology (RSM), and simulated annealing (SA) techniques. Experimental investigations revealed the significance of the number of passes in reducing grain size by up to 1.9 µm, consequently enhancing both mechanical and corrosion resistance properties, notably in route Bc. The corrosion rate was enhanced by 97.6 % while the corrosion resistance was increased by 254 % compared to the as-annealed condition. RSM and simulated annealing optimization results closely aligned with experimental findings. The evaluation of each extrusion parameter revealed that the correlation coefficient, as determined by the optimized Gaussian Process Regression model, ranged from 94 % to 97 % for all evaluated responses, and near to unity via ANNW. The overall distribution of mechanical and corrosion measures showed a significant correlation with the number of passes, with route A, Bc, and die angle following closely behind. Interestingly, route Bc had the main impact on the yield strength, followed by the number of passes and die angle. Thus, the combination of statistically and mathematically selected techniques effectively promotes the attainment of optimal properties. Furthermore, the Simulated Annealing (SA) algorithm demonstrated its capability to provide optimal solutions for ECAP deformation parameters. This study presents a promising avenue for improving the accuracy of ECAP-induced structural optimization in ZX30 alloy.