Effect of Displacement Rate on Sharp Millimeter Indentation

摘要

Indentation is widely used to investigate the elastic and plastic properties of materials, which include strain rate dependence. However, the results of the general micro-indentation test were affected by the microscopic scale of materials (e.g., surface roughness, and crystal grain size distribution), since the displacement was small. In the present study, we develop the sharp millimeter indention expanded displacement without the microscopic scale of materials. Furthermore, the effect of displacement rate on the sharp millimeter indentation was evaluated using the quasi-static and impact indentation test. In this study, high purity aluminum, with 99.99 mass%, was selected as the material with strain rate dependence of strength. The quasi-static indentation test was performed using the universal testing machine at the displacement rate of 8.3 ×10~(-7) m/s, 8.3×10~(-6) m/s, and 8.3×10~(-5) m/s. The impact indention was carried out at the displacement rate of approximately 3×10° m/s. The loading curvature decreased with increasing displacement immediately after indentation, and then this value was convergent, regardless of the displacement rate. It was clear that this convergent value was affected by the displacement rate.