The P-h~2 relationship on load-displacement curve considering pile-up deformation mode in instrumented indentation

摘要

A microhardness tester equipped with a Vickers indenter allows the determination of mechanical properties of a large variety of materials by analyzing load-displacement curves. In present work, a new model to compute the coefficient of proportionality K (named K-factor) between P and h relating to the pile-up have been developed. It was proved that indenter tip defect must be absolutely considered for an accurate determination of the contact area reducing an overestimation of mechanical properties and better fitting the loading curve. The proposed model is validated on a large variety of materials, i.e. carbides, nitrides and oxides showing sink-in phenomenon and steel, stainless steel, brass, bronze and copper having pile-up deformation mode. The model is compared with previous developed ones for sink-in and pile-up that can be easily applied but ignoring deformation mode and discarding the indenter defects will lead to not quite right no phenomenologically representative mechanical properties.