PLASMA IMMERSION ION-IMPLANTATION OF 100CR6 BALL-BEARING STEEL

Most low alloy steels are tempered al relatively low temperatures, lim iting the opportunities for improving their wear resistance and surfac e hardness by traditional heat treatment processes. In this work, we u se plasma immersion ion implantation (PI3) to apply a hybrid ion impla ntation/thermochemical diffusion treatment to ball bearing steel 100Cr 6 (1% C, 1.5% Cr). By a judicious choice of implantation voltage, temp erature and time, it is possible to combine the PI3 treatment with the tempering stage of heat treatment, without compromising the hardness of the alloy. Up to 200 degrees C, the bulk hardness (750 HV tempered) of the material is maintained, and nitrogen implantation increases th e surface hardness due to the precipitation of fine Fe2N. At 300 degre es C, where enhanced nitrogen and carbon diffusion can occur, the bulk hardness decreases, although in many applications this can be compens ated by the increase in surface hardness to around 900 HV0.1 due to Fe 3N and Fe4N formation. Wear and corrosion tests reveal significant imp rovements in comparison with untreated steel.