Analysis of the size effect in the nanoscratching process of single crystalline and polycrystalline materials

In tribology, nanoscratch testing is used to evaluate the mechanical and tribological properties of materials by employing a nanoscale indenter. At this scale, size-dependent plasticity effects, particularly those related to scratch hardness, become significant. Additionally, the anisotropic nature of crystalline materials means that the crystal orientation of the samples plays a crucial role. This study focuses on investigating the effects of indentation, grain size, and crystal orientation by applying the finite element method (FEM) with a lower-order strain gradient crystal plasticity framework. Results for scratch hardness, friction coefficient, and pile-up patterns are analyzed to identify the experimental trends, providing insights into how size and orientation effects influence material behavior in nanoscratch testing.