Modeling the precipitation kinetics and tensile properties in Al-7Si-Mg cast aluminum alloys

The extensive application of Al-7Si-Mg cast aluminum alloys in the automotive and aerospace industries raises the need to better understand the relationship between microstructures and properties. In present work, an integrated precipitation/strengthening/strain-hardening numerical model is developed in order to model the precipitation kinetics and tensile properties in Al-7Si-Mg alloys. The influence of solidification and solution treatment conditions on yield strength is reflected by a term ∆σ0. The strain hardening model takes into account the effect of Orowan loops on the dislocation storage and recovery as well as kinematic contributions. Application of this integrated model to various aging treatments of Al-7Si-Mg alloys is conducted and the predictions both for precipitate microstructure and yield strength are compared well with experimental results. The influence of aging temperature, solution treatment temperature as well as Mg concentration on yield strength is investigated. Using the strain hardening model, the stress-strain curves are predicted and the influence of aging treatment on k1 and k20 parameters as well as the strain hardening behavior is analyzed. Through combining with the empirical expression (σUTS−σYS)=m·σYS+n+f(Tss), the ultimate tensile strength and elongation for the samples in Al-7Si-Mg alloys aged at 160 °C and 180 °C are predicted. Finally, the limitations of present model and the factors influencing the prediction precision of tensile properties are discussed.