DEVELOPMENT OF HIGH-ACCURACY HARDNESS STANDARD BLOCKS IN JAPAN AND FUTURE OUTLOOK

Abstract The sources of problems with a hardness testing machine that are detectable via day-to-day inspection using hardness standard blocks, or indirect verification, can be roughly divided into three: the indenter, the test force, and the indentation measuring apparatus. If any problems are detected, repair or recalibration of the testing machine, focusing on the aforementioned three factors, is carried out based on the results of verifying the direct accuracies of that machine. These efforts have been accumulated to acquire the high level of hardness testing technology as is available now. This article describes the development of a hardness standard block as a tool for indirect verification of hardness testing machines, discusses possible factors that have effects on hardness measurements, and provides insights into the future hardness tests from a perspective of a hardness block manufacturer