How does Stainhard works?
Depending on the application, there are various process options, with the aim of achieving the desired properties.
During the Stainihard® process the surface will be enriched with nitrogen and carbon in a special way. With austenitic stainless steel this is not simply possible. Nitrogen and carbon diffuse at a low temperature (<450 ° C) in the product surface. The result is a very high surface hardness (1200-1400HV0.05) without negatively affecting the corrosion resistance!
Composition and structure
The Stainihard® layer is an expanded austenite zone (also called S-phase). This zone consists of the relevant stainless steel material with a supersaturation of nitrogen and carbon. Because of this supersaturation, compressive stresses arise. This increases the hardness considerably, without negatively affecting the corrosion resistance. The reason is, with Stainihard NC the formation of chromium nitride (CrN) and / or chromium carbide (CrC) is suppressed (expanded austenite). This in contrast to the classical nitriding processes such as salt bath and plasma nitride, where the corrosion resistance will decrease considerably as a result of the formation of this chromium nitride and carbides!
The depth of this expanded austenite layer formed by Stainhard is partly dependent on the chosen stainless steel material, the deformation degree and the surface condition.