IMPROVING ABRASION WEAR BY SURFACE-TREATMENT

An increase in the abrasive wear resistance of hardened and tempered hot-work die steel can be achieved by the use of surface treating processes, such as nitrocarburizing, plasma nitriding and spark discharge cladding, which produces a hard surface layer of WC-Co alloy. The dry abrasive wear test used in this investigation takes place in a dry air atmosphere and uses ferric oxides as the abrasive to form a range of surface topographies. In this test, the smooth surface of each specimen is subjected to rolling, and this results initially in groove and scar formation; subsequently the surface roughens and substantial amounts of debris are produced. The test results show that there is a linear relationship between the wear weight loss and the wear time. Metallography and X-ray diffraction, respectively, were used to examine the wear surface and the debris. It is clear that the abrasive wear resistance of a hot-work die steel can be improved by means of these types of surface treatments, most notably plasma nitriding. The phenomenon of abrasive wear is explained in terms of the wear test and metallographic results and the wear mechanism for these conditions is postulated.