Micromechanics of pyramidal indentation in fcc metals: Single crystal plasticity finite element analysis

This work concerns analysis of Vickers and Berkovich indentation experiments through extensive crystal plasticity finite element simulations. The simulations are performed by recourse to the Bassani and Wu hardening model for pure fcc crystals undergoing both easy-glide stage I and stage II deformations, as well as with the model proposed by Pierce, Asaro and Needleman for precipitation hardened fcc crystals, deforming initially under stage II which also undergo strong hardening saturation in stage III. Simulations are also conducted with a model based on the hardening description by Bassani and Wu, whose physical basis and predictive capability have been enhanced for pure copper crystals. Based upon the activity of the slip systems and the strength of dislocation interactions, this work provides a fundamental insight into the influence of prior work hardening in single crystal indentation. Discussions are given on the role of the latent hardening description upon the development of material pileup and sinking-in at the contact boundary as well as on the correlation between the single crystal and polycrystalline contact responses. The present investigation further illustrates on the influence of the orientation of the slip systems with respect to the pyramidal tip upon the formation of irregular imprint morphologies. Extraction of the single crystal hardening parameters from instrumented indentation P  –hshs curves is also briefly addressed. Finally, the contact deformation regimes ruling the response of isotropic strain hardening media are examined in light of the simulations for single crystal indentation.