Nitrogen ion bombardment of steel samples has been studied by utilizing the Delft variable energy positron beam facility. The energy of the beam was varied between 250 eV and 25 keV and a line-shape parameter S describing the annihilation radiation has been measured. By use of the VEPFIT fitting programme, up to five different layers, each having different densities, could be identified and characterized. The results show that carbon layers deposited during nitrogen implantation can be observed. A relation between the measured depth profiles of nitrogen, carbon and oxygen by Elastic Recoil Detection Analysis (ERDA) and the results of positron annihilation is given and discussed. The wear and friction properties of the steel surfaces before and after nitrogen implantation are presented.