Abrasion resistance as a function of substructural changes in steel

It is known that there are three different stages of wear rate as a function of the abrasive grit diameter. The first shows only a modest increase in wear rate when the grit diameter increases. Then, in the second stage as the grit diameter further increases, the wear rate rises rapidly. In the third stage, the wear rate becomes independent of the grit diameter or increases only slightly. The main objective of this work is to explain these dramatic changes in wear rate. For this purpose, two-body abrasive wear tests were performed in order to study the structural changes in different steels, depending on the abrasive grit diameter. Special attention was paid to the correlation between the size of the fragments (subgrains) formed in the surface layers and the variations in the wear rate. The former determines work hardening of the metal, and therefore, its wear resistance. X-ray investigation showed that the size of the fragments formed in the surface layers of steels during the wear process is dependent on the abrasive grit and corresponding wear rate. In the first stage, the size of the fragments is relatively small. Then, it becomes larger, and therefore, work hardening of the surface layers decreases by comparison to those under wear with a smaller grit diameter. The dimensions of fragments are maximal and change only slightly in the third stage when we used abrasive paper of a greater grit size. Therefore, in these cases, work hardening of surface layers is minimal and it is expected that wear resistance will also be minimal.