The Present and Future of Hardness Standard Blocks

摘要

Looking at the current status of hardness standards, we occasionally come across the view that it is sufficient that hardness measurements can be matched somewhat forcibly to the hardness values of standard blocks. However, if the direct accuracy of a hardness tester and indenter and loading conditions are well managed and appropriate testing procedures are taken, the measurement of hardness should naturally agree with the value indicated on a standard block, and "hardness" should be an industrial quantity obtained in that way. Therefore, we should recognize anew the original purpose of a hardness standard block as a standard tool, such as the daily inspection (indirect verification) of a tester and/or whether testing practices are under proper management, as well as to make a comparison between testers and/or between indenters. From this standpoint, we, in the capacity of a dedicated test-block manufacturer, discuss the principles of hardness test methods, the uniformity, durability and trends of hardness standard blocks, and future hardness standards relative to the ISO standards, based on our past results from testing and experiments with a number of standard blocks.