Strain gradient plasticity modeling to evaluate material plastic deformation behavior during Cold Gas Dynamic Spray process

Severe plastic deformation (SPD) is main feature of Cold Spray process resulting in producing ultra-fine metal grain refinement under extensive hydrostatic pressure and during high strain rate loading conditions. An isotropic strain gradient plasticity model (SGP) is presented to describe material deformation behavior during both low- and high- pressure Cold Spray processes. The enhanced dislocation densities produced throughout particles deformation affect coating material properties and thereby modify its kinetic and thermodynamic characteristics.

This study demonstrates that the SGP model is capable of describing the experimentally observed trends and accounting for a homogenization of the accumulated strains under dynamic recrystallization conditions. The evolution of statistically stored dislocation density through the characteristic material length scale is in a good agreement with experimental results and with data reported by other research groups. The proposed SGP modeling is suggested as an express method to evaluate properties of advanced coating, additively manufactured materials and powder metals used in thermal spray and 3D printing applications.

Keywords: Severe plastic deformation, cold spray, additive manufacturing, strain gradient plasticity, statistically stored dislocation, powder materials.