Analysis of the Applicability of Heat Treatment of EN AC-46000 Alloy Castings Made with Vacuum-Assisted HPDC Technology

The aim of the study was optimization of the technological parameters of the thermal treatment of EN AC-46000 alloy products made in the vacuum aided HPDC technology in the function of simultaneous maximization of the alloy’s mechanical properties with no deformation of the cast’s surface. The produced casts were subjected to thermal treatment T6 according to the elaborated experiment plan. The samples were examined in respect of selected mechanical properties as well as the presence of deformation on the castings surfaces. Also performed was an analysis of the castings microstructure as well as optimization of the technological parameters of the supersaturation and ageing process by means of statistical methods, i.e. the Box-Wilson optimization method (Stage I) and stepwise multiple regression in the Statgraphics software (Stage II). Also, a simulation was carried out, predicting the mechanical properties for the specific supersaturation and ageing parameters, from which optimized values of the setpoints of both processes were obtained. The study presents the results of validation tests of pressure casts subjected to thermal treatment performed according to the previously determined optimal parameters of supersaturation and ageing. These results confirmed the effectiveness of the conducted precipitation hardening treatment.