Indentation size effects: A study via finite similitude scaling theory

• Establishing a multiscaled approach for indentation experiments. • Capturing indentation size effects and addressing high-temperature analysis. • Correlating low to high-temperature responses while accommodating the indentation size effect. • Bridging nano- and macro-indentation measurements without any fitting parameters. Indentation is a widely applied measurement technique that can be reasonably categorized as nondestructive for evaluating mechanical properties. It is practically attractive and favored because it is easy to use and quick to apply at relatively low cost. Despite these advantages, indentation can be afflicted by indentation-size effects, and barriers to its application at elevated temperatures, which include indenter wear and failure. This paper examines these concerns in light of the new finite-similitude scaling theory that can potentially relate material responses of different-indenter sizes and at different temperatures. The methodology presented in this work introduces a multiscaled approach with data recovered at one, two, and three sizes per the rules of similitude theory. It is demonstrated in the paper, through indentation experiments, that hardness values at any specified depth can be accurately reproduced by combining hardness data from two distinct scales. Additionally, with data recovered at three scales, it is shown possible to relate low to high-temperature responses, circumventing practical difficulties with high-temperature measurement. Through simulation and comparisons with experimental data, the potential for similitude correction is demonstrated, achieving high accuracy in hardness recovery for crystalline materials, with errors primarily below 9%, and temperature-dependent hardness recovery with errors under 4%.