Housing parts for components which operate close to a combustion engine could, if utilized in future electric vehicles, be produced from more heat sensitive alloys. High-strength Al-Mg-Zn alloys represent an interesting material for this purpose. An extensive literature research in the theoretical part of this thesis was applied to the alloy system Al-Mg-Zn-(Cu). A study of possible heat treatments and their effects on the alloy properties, its microstructure and a subsequent comparisons to other aluminum-based alloys was accomplished. Various heat treatments were applied to the alloys AlMg4.5Zn3 and AlMg4.5Zn3Cu0.5. Different artificial aging strategies were carried out at constant temperatures additionally to heat treatments using two-step methods. The goal of the research was to find heat treatment parameter combinations resulting in maximized mechanical properties. Yield strength values exceeding 350 MPa were achieved using a two-step heat treatment consisting of three hours of artificial aging at 100 °C followed by approximately one and a half hour at 175 °C. The maximum yield strength value of 400 MPa was reached after two weeks of prior natural aging followed by two days of artificial aging at 125 °C. The two alloys behave comparable in all experiments, with slightly higher values for the copper free alloy. Only low values were obtained for both alloys for the elongation to fracture. Following the analysis of the phases in the microstructure, the recommendation can be derived that in the future both the manganese content and the silicon content should be optimized. Through implementing these alloy changes the elongation values should increase significantly.
|Translated title of the contribution
|Optimization of aging treatments in the Al-Mg-Zn-Cu alloy system
|14 Dec 2018
|Published - 2018
Bibliographical noteembargoed until null
- artificial aging
- multistep aging