Analysis of the Mechanical Properties of Secondary AlZnMg(Cu) Die-Cast Alloys

Abstract

In this work, the development of AlZnMg(Cu) alloys was performed by thermodynamic simulations and experimental tests. With calculations, the solidification processes and phase compositions could be predicted. As secondary casting alloys, the selected compositions of AlZn4Mg3-Cu(Fe) and AlZn5Mg4Cu have higher contents of alloying elements, such as iron and silicon, and were successfully processed with a cold-chamber die casting machine. In addition, an energy-and time-saving optimization of the material properties was performed by a modified heat treatment (T6*) with a total time of only 12 h. The alloys were evaluated based on the characterization of their mechanical properties and the analysis of their microstructures. In particular, the elimination of cost-intensive alloying elements and the application of a modified heat treatment method clearly show the potential of AlZnMg(Cu) die-cast alloys for future industrial use.

Influence of Die Casting Speed on Properties of Casting Based on Al-Si Alloys

“…Selection of the right speed of the mould cavity filling depends on the alloy type, the casting complexity, the wall thickness, and the ratio of the gate area and the area of casting. The dependence of optimal speed in the ingate on the wall thickness and on the length of casting is shown in Figure 1 [ Majernik 2016, Silmbroth 2020]. The character of the melt flow in the mould cavity depends on input melt speed into the mould cavity, mutual relation of the ingate thickness and the casting or their areas, viscosity and surface tension of the melt, and thermal conditions which are formed due to reciprocal influence between the melt and the mould.…”

“…During crystallization, hydrogen is released in the form of pores and bubbles. Water vapour also leads to the formation of hydrogen bubbles and therefore porosity of the casting was examined as it is directly influenced by the change in the melt temperature [Gaspar 2019, Silmbroth 2020]. To detect porosity, the parts of the casting were used which were identified as the spots of the possible occurrence of increased porosity with regards to changing pressing speed considered to be the technological parameter of die casting.…”