Research on gas nitriding process and performance of 25Cr2MoV steel

This paper investigates the feasibility of improving the surface hardness, wear resistance, fatigue strength, and corrosion resistance of 25Cr2MoV steel through gas nitriding. The experiment tested various nitriding potentials (3, 1, 0.5, 0.2) at 520°C for 5 hours on quenched and tempered 25Cr2MoV steel. The microstructure, phase composition, brittleness, and wear performance of the nitrided layer were systematically analyzed using microstructure observation, XRD analysis, Vickers hardness testing, and wear tests. Results show that as nitriding potential decreases, the thickness of the compound layer significantly reduces, while the depth of the nitrided layer remains unchanged. At lower nitriding potentials (K_N=0.2, 0.5), the γ′ single-phase compound layer on the surface exhibits higher plasticity and wear resistance. Conversely, higher nitriding potentials (K_N=1, 3) increase the ε phase content, leading to greater surface brittleness and reduced wear resistance. This study demonstrates that optimizing gas nitriding process parameters can significantly enhance the overall performance of 25Cr2MoV steel, offering an effective surface strengthening method for practical engineering applications.