Properties of surface layer generated by new combined process of burnishing and nitriding

The results of a metal surface layer (MSL) investigation are presented in the present article. The surface layer was created using a new technological process. This process is the result of a combination of mechanical treatment (i.e. burnishing) and thermochemical treatment (i.e. nitriding). As a result of increasing the dislocation density during a burnishing treatment, which is followed by a nitriding treatment, the diffusion process in MSL is intensified. In the present article, specimens made of Armco iron (as a model material) were investigated. Four different stages of the surface layer development were investigated, i.e. initial material (after annealing), material after burnishing, material after nitriding and material treated by the combined technology. The main goal of the investigations carried out was a comparison of the changes in properties of the surface layers as a result of the different technologies. Investigations were performed on the metallography of different MSL structures, nitrogen concentration and hardness together with stress measurements.