AISI H13 tool steel presents a good combination of mechanical strength and toughness, with this, they are used, as examples, in the manufacture of aluminum extrusion dies, hot forging dies and injection molds of non-ferrous materials and polymers. These tools, in practice, are subjected to tensile and compression stresses during the heating and cooling process, which lead to thermal fatigue and also to wear. To extend the life span of these tools, new surface treatments are being researched. In the present work, the influence of quenching treatment on the surface properties of nitrided AISI H13 steel was studied. First, gas nitriding was carried out at a temperature of 540ºC with time durations of 84 hours. Then, nitrided steels were subjected to salt bath quenching at a temperature of 1030ºC with time durations of 50 minutes. The salt bath quenching treatment on the nitrided AISI H13 steel generated an increase in the depth of the nitrided layer of 57%, caused by the additional diffusion of nitrogen towards the core of the specimen, a reduction in the microhardness of approximately 30% in the region of the new nitrided layer and 9% to 20% increase in core microhardness. In this new nitrided layer, formed after quenching, it was possible to identify, by X-ray diffraction, a reduction in the intensity of the peaks of the ε nitride phase, disappearance of the γ' phase, the appearance of new peaks, such as α' phase (martensite ), γ-phase (retained austenite), CrC carbides and V(C , N) carbonitrides.
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