Elastic-plastic indentation: Hardness and fracture

Abstract The nature of the stress functions which occur at an elastic-plastic indentation under static load and after unloading are considered. The analysis provides a self-consistent explanation of the fractographic nature of Palmqvist cracks and the potential for the growth of these cracks in the near-surface region adjacent to an indentation. It also provides a good correlation of available data for the variation of indentation hardness with mechanical properties of the test material. The paper falls into two separate parts: that which involves the formal development of the stress analysis, and that which considers its physical implications in terms of indentation and tribological principles.