IMPROVEMENT OF WEAR RESISTANCE OF BEARING STEEL SHKH15 BY PLASMA HARDENING UNDER DIFFERENT PROCESSING CONDITIONS

This study investigates the effect of plasma hardening under different processing conditions on the microstructure and tribological properties of bearing steel ShKh15. It is shown that plasma treatment, based on localized high-speed heating followed by self-quenching, enables the formation of a hardened surface layer without the use of liquid cooling media. Experimental studies were carried out by varying the plasma arc current (120-140 A) and the flow rate of the plasma-forming gas (0.2-0.25 L/min).The results demonstrate that plasma hardening leads to the formation of a gradient microstructure consisting of martensite, retained austenite, and pearlite, with a smooth transition to the initial pearlitic structure. The maximum microhardness of the hardened layer reaches up to 700 HV with a depth of up to 250 μm. Tribological tests using a ball-on-disk configuration showed that after plasma treatment, the coefficient of friction increases, while the wear rate decreases by 3-3.5 times compared to the initial state. The obtained results indicate a significant improvement in the wear resistance of ShKh15 steel and confirm the effectiveness of plasma hardening as a surface strengthening method.

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