An Influence of Nitrogen Corrosion on Microstructural and Mechanical Features of the X5CrNi18-10 Steel

Corrosion-resistant steels form an important group of structural materials who’s mechanical and corrosion-resistant properties are an irreplaceable part of the engineering industry. Despite their designation as "stainless steel", it is necessary to consider that even these steels can be subject to various types of corrosion attack under certain conditions. The article presents the effect of a controlled protective nitrogen atmosphere on X5CrNi18-10 steel, which is used to produce auxiliary components in the automotive industry. Steel X5CrNi18-10 is not only subject to corrosion after a short time (2hr) in a nitrogen atmosphere, at a temperature of 570 to 630°C, but at the same time the mechanical properties also change. Nitrogen atmosphere is used in heat treatment in automotive and X5CrNi18-10 steel is often used in these conditions as an auxiliary material, e.g. base grid. One test for X5CrNi18-10 steel was that the samples were exposed to a nitrogen atmosphere at various temperatures and then the agreed yield stress Rp0.2, hardness and microstructure were evaluated. The second test was the evaluation of the frame made of the given steel at 630 °C. The testing took place in a continuous furnace. Temperatures above 500 °C significantly changes the material's features.