Enhancement of surface properties of 45# carbon steel using plasma immersion ion implantation

Abstract 45 # carbon steel is commonly used in the industry but vulnerable to wear and corrosion in the field. Replacing it with stainless or alloy steel increases the cost significantly, and a better alternative is to improve its surface properties and lifetime using plasma immersion ion implantation (PIII). We have evaluated a variety of treatment processes including nitrogen PIII, radio-frequency (RF) plasma nitriding together with nitrogen PIII, Ti (Cr) deposition in conjunction with nitrogen PIII (IBED), as well as nitrogen PIII on samples electroplated with a layer of hard Cr. To assess the efficacy of each process, the microhardness, mass loss due to wear, coefficient of friction, and anode polarization curve were measured on both the untreated and treated 45 # samples. Our experimental results show that the surface properties of 45 # steel are enhanced by all of these methods, but to a different extent. The IBED technique produces the best enhancement data. For instance, the microhardness increases by almost a factor of 2, mass loss due to wear is reduced by 31/2 times, and the coefficient of friction diminishes by 21/2 times. The RF plasma nitriding/nitrogen PIII technique produces less dramatic enhancement results but is more desirable for complex-shaped industrial components. The hard Cr-electroplating/nitrogen PIII technique is excellent but appears to be least desirable because of environmental impact.