Influence of the material composition on the nitriding result of steels by plasma immersion ion implantation

The influence of different alloying elements and their concentration on the nitriding behaviour of steel by plasma immersion ion implantation (PI3) was examined. Treatments were performed at 300°C using different high voltage (HV) repetition rates of 100, 200 and 300 Hz. The steels were alloyed either with 0.09, 0.45 and 0.9 wt.% C, 0.11, 0.3 and 0.93 wt.% Al or 0.93, 3.6 and 13.2 wt.% Cr. The nitride formation for the various alloys and parameters was studied using X-ray diffraction (XRD) and metallographic cross-sections in scanning electron microscopy (SEM), showed a nitride formation that is strongly influenced by the material composition. Additional information is obtained by glow discharge optical emission spectroscopy (GDOS) depth profiles and instrumented microhardness measurements. The effect of the HV repetition rate is not very clear, as on the one hand the implanted dose is increased, but on the other nitride formation seemed to be disturbed by higher repetition rates. The results will be discussed under the aspect of improving the nitriding efficiency of PI3.