A Yield Stress and Work Hardening Model of Al-Mg-Si Alloy Considering the Strengthening Effect of β and β' Precipitates

Precipitates are the primary source of strength for the Al-Mg-Si alloy. Aluminum alloy in the peak-aged state mainly contains beta and beta' precipitates. Most of the literature has only considered the strengthening effect of beta. Here, we develop a single-crystal intensity model including both precipitate enhancement effects for the first time. This model was subsequently implemented into a crystal plastic finite-element method to model the uniaxial tensile process of a polycrystalline aggregate model of Al-Mg-Si alloy. The simulation results for uniaxial stretching are in good agreement with the experimental results, confirming that the constitutive parameters used for the single-crystal strength model with two precipitates are based on realistic physical implications. Furthermore, by comparing the uniaxial tensile simulation results of a peak-aged alloy considering the actual precipitated phase composition of the alloy with those assuming that the precipitated phase is only the beta phase, the predicted tensile strength of the former is around 5.65% lower than that of the latter, suggesting that the two kinds of precipitation should be separately considered when simulating the mechanical response of Al-Mg-Si alloy. It is highly expected that the present simulation strategy is not limited to Al-Mg-Si alloys, and it can be equally applied to the other age-enhanced alloys.

Automated summary

This study develops a single-crystal strength model including precipitate enhancement effects and applies it to the mechanical simulation of Al-Mg-Si alloy. The simulation results agree well with experimental results, indicating the realistic physical implications of the model. The study also suggests that different precipitate phases should be separately considered when simulating the mechanical response of Al-Mg-Si alloy.