The paper deals with the change in mechanical properties and wear of 90MnCrV8 universal tool steel after plasma nitriding, which is widely used to produce cutting tools with good durability and low operating costs. Plasma nitriding was performed at a temperature of 500 °C for 10 hour period in a standard N2 /H2 atmosphere with 1:3 gases ratio. Microstructure, phase structure, thickness of a nitriding layer and surface roughness of samples were measured with optical microscopes and a profilemeter. Verification of a chemical composition was carried out on the BAS TASMAN Q4 device. Wear resistance was measured on a universal TRIBOLAB UTM 3 tribometer, through a "pin on disc" method. The results of experiments have shown that plasma nitriding process, significantly improves the mechanical and tribological properties of selected materials.

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The 42CrMo4 steel is a material popularly used in weapon manufacture. This article that deals with improving wear resistance of gun components will study tribological behaviour of above steel, treated by plasma nitriding technologies under different condition of duration and gas ratio. The friction coefficient and wear rate were investigated using the wear test based on principle “ball on disc”. The results were supplemented with mechanical properties and metallographic documentations. The results show that plasma nitriding improved dramatically the mechanical properties and wear resistance of materials, and the level of wear resistance was related to the nitriding process parameters.

The impact of plasma nitriding process on corrosion resistance of ferrettic stainless steel (FSS) was evaluated in this study. The FSS X12Cr13 (AISI 410) was subjected to low-temperature plasma nitriding (LTPN) treatment at a temperature of 400°C in 3H2:1N2 (l/h) and in 1H2:3N2 (l/h) reverse working atmosphere (LTPN-R) and to high-temperature plasma nitriding (HTPN) treatment at 550 °C for 15 h. The microstructure and microhardness of the untreated and nitrided stainless steel were evaluated. The corrosion properties of the untreated and plasma nitrided steel samples were evaluated using the anodic potentiodynamic polarization tests in neutral 2.5% NaCl deaerated solution. The phase analysis showed that LTPN and LTPN-R treatment on the AISI 410 steel led to the formation of aN layer (nitrogen expanded ferrite) accompanied by Fe3C and Fe4N iron nitrides and CrN. The HTPN technique led additionally to the formation of an increased volume of Cr4N4 chromium nitrides and Cr15Fe7C6 chromium iron carbide. The plasma nitriding process significantly increased the microhardness of the ferritic stainless steel. The pitting was evaluated, and the pitting coefficient was calculated. The electrochemical corrosion tests showed the best corrosion resistance of the untreated X12Cr13 stainless steel, only slightly increased corrosion rates of LTPN and LTPN-R techniques, and extreme corrosion rates after application of the HTPN technique, causing Cr depletion and thereby suppressing the ability to passivation.

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