薄板のロックウェルかたさ測定について

アンビル表面あらさおよび試料裏面あらさの影響

抄録

The Rockwell superficial hardness tester is generally used to measure the hardness of thin metal sheets. The measurement of such metal sheets as those which have comparatively low hardness (H_V<200) is practiced with ball indenter and spot anvil as a rule. In this case, as the plastically deformed region would often reach the reverse surface of the specimen, the peculiar phenomenon well known as anvil effect lowers the reliability of hardness values. It is expected, moreover, that the difference of roughness of either the anvil surface or the reverse surface of the specimen will affect the hardness values.
In our study, we investigated experimentally how the roughnesses of either the anvil surface or the reverse surface of the specimen would affect the Rockwell superficial hardness readings of thin metal sheets. From these results, we have found an empirical formula which defines the interrelationships of variations in hardness, in the roughness of the surface, in the thickness of the specimen and in the depth of indentation, in order to obtain reliable hardness value. By using this formula, we shall be enabled to devise rational methods for preparing specimens and measuring their hardness.