Estimating the slip resistance from spherical nanoindentation and orientation measurements in polycrystalline samples of cubic metals

Abstract

In this paper, we demonstrate the first application of a recently formulated two-step approach to the estimation of the average slip resistance in a cubic polycrystalline metal sample from a collection of spherical nanoindentation and lattice orientation measurements. In the first step, a crystal plasticity finite element model of the spherical nanoindentation experiment is developed, validated, and employed to capture the functional dependence of the indentation yield strength on the crystal lattice orientation at the indentation site. This functional dependence is captured in a compact representation using surface spherical harmonics (SSH) functions. In the second step, measured values of the indentation yield strength and the crystal lattice orientations at the indentation site from a polycrystalline sample are fit to the function established in the first step to provide a robust estimate for the value of the average slip resistance in the sample. The validity of this approach is demonstrated for cast and annealed Fe-3% Si using measurements published in prior literature.