Min Yong-an

Effect of the compound layer of plasma nitriding on thermal fatigue behavior of 4Cr5MoSiV1 die steel

With the Uddeholm self-restricted method, the effect of compound layer of plasma nitriding on thermal fatigue behavior of 4Cr5MoSiVl steel was studied by the way of adding Ar during plasma nitriding to remove the compound layer. The results show that the compound layer of plasma nitriding can delay the nucleation of heat cracks and hold back the propagation of heat cracks from surface to substrate because of its high hardness and strength. On the other land, the heat checking expands faster with the compound layer on the surface than that without it. After 3000 cycles of thermal fatigue test, both heat cracks with the compound layer are wider than the another without compound layer and the number of heat cracks of the former is more from the view of cross section.