INFLUENCE OF PLASMA NITRIDING PARAMETERS ON THE MECHANICAL PROPERTIES OF 25Cr2Ni4W STEEL

In this study, plasma nitriding was applied to 25Cr2Ni4W low-alloy steel to improve its mechanical and tribological surface properties. The investigation focused on varying the negative bias voltage while keeping the discharge power, pressure, and holding time constant. The substrate temperature increased due to the self-induced heating mechanism. The compound layer of the treated samples revealed the formation of nitride phases (ε-Fe2-3N and γ'-Fe4N), as observed through XRD analysis and optical microscopy. A phase transition was noted between 2.0 kV and 3.5 kV, accompanied by an increase in the volume fraction of the γ '-Fe4N phase and a decrease in the volume fraction of the ε -Fe2-3N phase. When comparing the nitrogen-implanted samples to their untreated counterparts, an increase in nanohardness was observed, suggesting that the nitride phases contributed to the hardening.