The influence of microstructure on the Bauschinger effect in an Al-Si-Mg casting alloy

The Bauschinger effect has been studied in an Al-7% Si-0.4% Mg casting alloy for a range of dendrite cell sizes and aspect ratios of the Si particles. The internal stresses increase linearly with the imposed pre-strain for strains up to 0.007, gradually saturating thereafter. For a given value of the cell size the internal stresses reach a higher saturation value when the Si particles have a larger aspect ratio. At constant aspect ratio of the Si particles, smaller cell sizes result in higher internal stresses at large strains. Current models for dispersion hardening can be used to calculate the stresses in the particles. The calculations are in very good agreement with the experimental results.