Abstract:
Plasma nitriding is a thermochemical process of technological importance to reduce damage on the steel surface, improving die life. However, the properties of this layer may change, due to the conditions of use of the die. The industrial environment submitted the nitrided surface to temperatures up to 600°C and, in the literature, there is not a clear understanding of the microstructural stability of nitrided surface properties. Therefore, the aim of this study is to evaluate the effect of temperature on the nitrided layer of AISI H13 steel. Samples were hardened and tempered to 45 HRC and then nitrided aiming for a layer with a depth up to 100 μm, without white layer. After nitriding, some samples were annelead in a furnace at 600°C for 30min, 2h, 5h, 10h and 100h. Some samples were tested for microstructure, x-ray diffraction and residual stress. The nitrated layer, after being subjected to high temperature, presents a reduction of level in the residual tensions of compression, bringing about a process of tensions relief. The same effect is not so strongly verified in the material hardness profile