Optimization of AlSi10MgMn Alloy Heat Treatment Process Based on Orthogonal Test and Grey Relational Analysis

By applying the orthogonal test, the T6 heat treatment test of the casting AlSi10MgMn alloy was carried out. Hardness, tensile strength, and elongation were selected as indicators for evaluating the toughness of alloy. Grey relational analysis was used to comprehensively evaluate the toughness of the alloy. Based on multiple linear regression, prediction models of hardness, tensile strength, elongation, and grey correlation were established. Through planning and solving, the optimal T6 heat treatment process parameters were obtained. According to the results of the metallographic structure analysis and the fracture SEM on the alloy after the T6 heat treatment, aging time, solution time, and solution temperature were identified as the most important factors affecting alloy hardness, tensile strength, and elongation, respectively. Through the application of grey relational analysis, the optimal T6 heat treatment process of an AlSi10MgMn alloy was obtained, namely 530 °C/1 h + 190 °C/6 h. Based on the solving of the prediction models, the optimal T6 heat treatment process and solution temperature of AlSi10MgMn alloy were obtained, namely 530 °C/3 h + 190 °C/8 h. Under these conditions, the hardness of the alloy was 96.9 HV, the tensile strength was 344.6 MPa, and the elongation was 6.1%. In contrast, the toughness of the alloy was better than that obtained by grey relational analysis. The T6 heat treatment refined the microstructure of the alloy, which resulted in a significant increase in fracture dimples.