Influence of strain hardening
Hardness of common metals - Rigid limit case – plastic

Let's consider the indentation of a material collapsing according to Hollomon's law (cf. , equations (11). The stresses developed are proportional to the consistency σ ₁ , which acts as a simple scaling factor. The only effective parameter is therefore the strain-hardening index n which, depending on the nature of the material and its condition, can vary between 0 (the previous case of the perfectly plastic body) and 0.5 for hyper-hardened austenitic stainless steels, for example; n = 0.2 is a common value for a metal alloy (figure 5 ).