Abstract
The results of wear test on some kinds of carbon steels and cast iron in combination with carbon steels and cast iron prove that the wear loss is proportional to the hardness variation of the rubbing surface. The hardness of rubbed surface is measured by the microscopic Vickers hardmeter on 100 gram load. The surface hardness of steel increases on the low carbon side and decreases on the high carbon side. This phenomenon resembles the oxide film hardness reported in the 2 nd report. The oxide film generally protects abrasion but free oxide flakes or grains accelerate wear and soft material that produces hard oxides can easily wear out harder steel. As a consequence of the inordinate hardness increase on the rubbing surface of carbon steel In certain conditions, it is supposed that there are not only simple plastic deformation and oxidation but also quenching by radical heating and cooling.
