Influences of heat treatment and surface on thermal fatigue

Among the several damages that are subject to hot work tools, thermal fatigue figure as one of the most common failure mechanisms for the initiation of cracks. To improve the properties of these tool steels to this kind of failure, different types of materials combined with different parameters of thermal and surface treatments have been investigated using thermal fatigue tests. Several studies have reported the damage caused by thermal fatigue, usually by comparing the performance of different classes of material. However, few studies assess, under the same conditions, the thermal fatigue behavior under different conditions of surface to the same substrate. In this context, in order to better understand the influence of various types of heat treatments and surface on thermal fatigue resistance, the study aimed to evaluate and compare, in the laboratory, thermal fatigue resistance of specimens of the hot work tool steel AISI H11 modified with different surface treatments. For each group of specimens, the following treatments were performed: deep cryogenic, post-oxidation, nitriding/post-oxidation, nitriding/ PDV coatings (TiN), nitriding/ PDV coatings (CrN) and nitriding/ PDV coatings (TiBN). The results of the tests showed a greater resistance to thermal fatigue of nitreted surfaces with PVD coating.