Nanoindentation tests were performed on copper, tungsten, SUS316 and martensitic steel under the applied forces of 0.49, 0.98, and 9.8 mN; the measuring points were 100 for each condition. A good correlation between Wp / We (We: energy for elastic work, Wp: energy for plastic work), and elastic strain resistance (H / Er) was found for nearly all test conditions of applied force. The deviation of H / Er and Wp / We from the regression curve Wp / We - H / Er obtained from previous work was calculated by using the multiplying value of geometric mean of normalized root-mean-square error (GMNRMSE) for Wp / We and that for H / Er. The result showed that GMNRMSE was increased at the test force of 0.49 mN, compared with these of 9.8 mN and 98 mN for all materials. The present work shows that the nanoindentation test is effective for evaluating the mechanical property in terms of work energies, and that it is possible to evaluate the validity of nanoindentation tests by using the GMNRMSE.

A small ball rebound hardness tester is useful for testing hardness of various objects on site. However, it is difficult to establish direct relation between obtained coefficient of restitution (e) and material mechanical properties. In this study, a modified Tabor model and a maximum plastic model are compared with experimental results for coefficient of restitution, indentation diameter, and force. The maximum plastic model is better than modified Tabor model for e at least from 0.108 to 0.868.

Hard films prepared by deposition, nitriding and etc. to apply products of tribology are useful to extend the product lifetime. For the development, the mechanical properties of hardness and toughness of the films are very important parameters. The hard materials almost are brittle. The property relates to the lifetime. First, the hardness of the films is measured by Vickers hardness test. Next,the toughness must be measured. The fracture toughness of bulk is measured by JIS R1607. The hardness of the bulks of TiC and VC and the films of CrC and VC was measured by instrumented indentation tester on the condition of the high load. The hardness and the fracture toughness of the bulks and the films were investigated from the morphology of the indentions and the changes of the values of the hardness.