Influence of microstructure of alloy 718 on high strain rate deformation
Conference contribution, 2014
There are a number of situations where alloys for aero engines undergo deformation with high
strain rates, e.g. during metal cutting. To understand, model and predict the behaviour we need
knowledge of high strain rate behaviour, but also understand the influence of the microstructures.
The material investigated is Alloy 718, a precipitate heat treatable nickel base alloy, heat treated
to generate four microstructures; small and large grain size, aged and solution treated condition.
Split Hopkinson was used for high strain rate compression testing; the strain rates tested in
tensile and compression ranges 0.001-3000 s-1. To describe the deformation, the Johnson Cook
material model was optimized for each microstructure. Present microstructure is influencing the
stress response more than the strain rate and the different microstructures deform in slightly
different manner where small grains tend to deform in primary glide and large grains deform in
both primary and secondary glide systems.
high strain rate deformation