Low temperature gaseous nitriding of plastically deformed austenitic stainless steels
Federico Bottoli, Grethe Winther, Thomas L. Christiansen, Marcel A.J. Somers
Low-temperature gaseous surface treatments of stainless steels as nitriding and nitrocarburizing allow improvement of wear and fatigue resistance without impairing the corrosion properties. The improvement is related to the formation of nitrogen and/or carbon supersaturated solid solution known as expanded austenite. The colossal amount of nitrogen and carbon dissolved into the steel matrix is associated with a remarkable increase in hardness as well as development of high surface compressive stresses.
Most stainless steel components contain a certain degree of deformation due to prior machining which influence the properties of the material upon low-temperature thermochemical surface treatment.
In this experimental activity, the influence of plastic deformation on low temperature nitriding and nitrocarburizing is studied on several commercial alloys. The composition and morphology are analysed, and the residual compressive stress profile is determined.