Quenching Sensitivity and Transformation Kinetics of High Vacuum Die Casting Alsi10mgmn Alloys

Abstract

AlSi10MgMn alloy high vacuum die castings (HVDC) are being widely used in automotives. T6 heat treatment can increase the casting mechanical properties. In this work, the time-temperature-transformation (TTT) and time-temperature-property (TTP) curves of HVDC AlSi10MgMn alloys were measured by interrupted quenching method, and the quenching sensitivity range of the alloys was obtained. Based on the results, the quenching factor analysis (QFA) method was used to predict the mechanical properties of alloys at different cooling rates. The microstructure transformation of the alloys during isothermal process was analyzed by phase transformation kinetics. The results showed that the quenching sensitivity range was 295~445°C. According to the QFA, the critical cooling rate of the alloy was 7.7 °C/s. The phase transformation rate of the alloy at 460°C was higher than that at 280°C based on the results of phase transformation kinetics. The rod-shaped β-Mg2Si phases precipitated during the isothermal process and grew up with the extension of holding time, which reduced the density of the fine age-induced precipitates β '' and increased the range of precipitation free zone (PFZ) after the followed aging treatment.

Keywords: AlSi10MgMn alloy, high vacuum die castings, Quenching sensitivity, quench factor analysis, microstructure