Effect of strain rate on damage evolution in a cast Al-Si-Mg base alloy

An important aspect of damage evolution in cast Al-Si-Mg base alloys is fracture/cracking of Si particles. This microstructural damage is quantitatively characterized as a function of strain rate in the range 10(-4) to 3.7 x 10(+3), at an approximately constant uniaxial compressive strain level (20 to 25 pet). It is shown that the fraction of damaged silicon particles, their average size, and size distribution do not vary significantly with the strain rate, and at all strain rates studied, larger Si particles are more likely to crack than the smaller ones. However the stress-strain curves are sensitive to the strain rate. These observations have implications for modeling of deformation and fracture of cast components under high strain rate crash conditions.