Measurement of indentation diameter is a very important factor in Brinell hardness as it can determine the reliability of the result. It is because of the ambiguous boundary line due to the pile up around the indentation. To evaluate the capability of indentation measurement, we prepared Brinell indentation hardness blocks and performed the proficiency test. Participating test laboratories have reported that deviation increases at the nominal diameter of 3 mm or larger. The result of this study indicates that this was because of the generation of up to 0.02 mm deviation or higher uncertainty at the same indentation if the definition of measurement reference is different or unclear when measuring the diameter of indentation with large pile up. We provided Brinell hardness blocks with reference indentations to the participating laboratories which observed the problem in the proficiency test. After retesting, deviation was observed to improve by up to 90 %, thereby proving the importance of applying the reference indentation CRM in Brinell hardness measurement.

The one of difficulties is how to evaluate the origin of depth from force-indenter displacement curve in instrumented indentation test (IIT). One of determination technique it is that using the fitting using some model function. How to evaluate the uncertainty of the fitted coefficients is another problem in this case. We have been developing the uncertainty evaluation software and the uncertainty of fitting of power-law is evaluated by using the final Jacobian matrix of iteration process. In this paper, we explained the uncertainty calculation for the non-linear function. We applied it to the contact point estimation for force-depth curve obtained by the fused silica as a typical example. We also discussed the effect of model function and data length, which is obtained by the developed software.

Currently, about 30,000 high-precision, standardized hardness blocks are supplied to the Japanese market each year, and are available in about 140 different types. The history of hardness blocks in Japan can be traced back more than 70 years to the development of the Shore hardness block (φ64×t 15 mm) by Shoichi Yamamoto. In Japan, the Shore block has the largest share of the market for rebound hardness test blocks. Recently, however, the Leeb hardness block has also been increasingly used for rebound hardness testing, and the R type (φ115×t 33 mm) and P type (φ90×t 56 mm) Leeb hardness blocks are produced exclusively in Japan.
The successful expansion of the Shore hardness test in Japan is due to the use of Vickers hardness values, which are more reliable than Shore values, and the VHS conversion method adopted by the Japan Industrial Standards (JIS).
This paper discusses how differences in geometry between the R-and P-type Leeb hardness blocks influence Leeb hardness values. Based on hardness measurements using the Vickers and Leeb (HLD and HLE) hardness scales with these Leeb blocks, a method for converting Vickers hardness values into Leeb values is also discussed. As a result, no influence from geometric differences on the Leeb (HLD and HLE) hardness measurements is found, and conversion from Vickers to Leeb hardness can be defined by the same formula for both R-and P-type blocks.