On Indentation Hardness (2nd Report)

Abstract

In this paper, the author intends to describe the results of experiments regarding indentation hardness. These tests were carried out under load smaller than that in the case of the previous report. The depth of indentation was measured by using the method of Newton's ring. The range of load is as follows ; i.e. P/D2=0.006-0.202 kg/mm2 where P is the load applied and D the diameter of the ball used as the indenting tool. The author recognized in the present experiments that the hardness number based on the depth of indentation, as the measure of which the permanent displacement was adopted, took, on the contrarya, tendency of increasing with the decreasing of load in the range of considerably light load. The relation between the hardness and the depth of indentation in these cases is expressed as the results of the theoretical consideration by H=q0+q1h2+q2h-1. where H stands for the hardness number, h the depth of the permanent indentation and q0, q1 and q2 are all constant depending on the nature of materials. Experimental data showed a fairly good coincidence with this expression.