Microstructure, Composition, and Hardness of Rockwell C Hardness Blocks

摘要

The microstructure, composition, and hardness of hardness blocks (Rockwell Cscale) that are commonly available in the country were examined. Blocks near HRC levels of 25, 45, and 65 were obtained from each of six sources to represent the HRC measurement range. It was found that the steels used in the blocks had surprisingly high levels of impurity elements, which are one source of scatter in the hardness values. Other than the concern for the steel purity, it is concluded that most of these hardness block producers possess the technology necessary to manufacture a reference hardness block, or series of blocks, if it is found desirable for NIST to distribute a national hardness standard.