Nitrogen-alloyed Austenitic Stainless Steel Research Articles

Wear resistance of a high-nitrogen austenitic stainless steel coated with nitrogenated amorphous carbon films

In this paper, the dependence of wear resistance on grain size of nitrogen-alloyed austenitic stainless steel is investigated and compared to measurements for the same samples coated with nitrogenated amorphous carbon [a-C:H(N)] film, deposited by means of plasma-enhanced chemical vapour deposition. To this aim, ball-on-disk (BoD) tests were performed to investigate the wear stability of coated and uncoated substrates. Long-time test results on the uncoated material show that no improvement in the low-friction performance (LFP) duration was found with decreasing grain size of the substrate. On the other hand, an improvement in the low-friction performance duration with substrate microstructure refinement was found in the case of nitrogen-doped overcoats. An effect of the film structure on the LFP duration was also detected in the case of the finest-grained samples, indicating a synergic effect between the ultrafine grain structure and the nitrogen-doped carbon coating.

Localization of Nitrogen Atoms in Nitrogen Alloyed Austenitic and Ferritic Stainless Steels by EXAFS Studies

Extended X-ray absorption fine structure spectroscopy (EXAFS) was performed for localizing nitrogen atoms in two austenitic steels, such as X5CrNi 1810 (AISI 304) and X5CrNiMo 18 8 3 (AISI 316), as well as in the ferritic steel X20CrMo 9 1 in the as-received condition and after salt bath nitriding. The evaluation of the EXAFS data revealed structural distortions in the neighbourhood of the alloying elements caused by interstitially dissolved nitrogen atoms, The strongest lattice distortions were detected around Cr and Mo atoms. This indicates that the stable nitride forming elements Cr and Mo are favourable hosts for nitrogen atoms

Work-hardening behaviour of nitrogen-alloyed austenitic stainless steels

This study analyses the plastic flow behaviour of types 316L and 316LN austenitic stainless steels. The following features are shown. 1. (i) The yield stresses vary quasi-linearly with the nitrogen content. This is attributed to the linear variation in the thermal component with the interstitial concentration, according to the Friedel model. 2. (ii) The monotonic work hardening of these steels can be modelled by the modified Ludwik model proposed by Ludwigson: σ = ϰ 1 ε n 1 + Δ, which takes into account the positive deviation from the Ludwik relation, which appears below a transient strain ε L. This transition corresponds to a change in the dislocation slip mode, essentially planar below ε L and multiple above ε L. 3. (iii) The influence of nitrogen on Ludwigson's modelling parameters is adequately explained by the fact that the nitrogen favours planar dislocation slip in the austenitic stainless steels.

Room-temperature elastic constants and low-temperature sound velocities for six nitrogen-alloyed austenitic stainless steels

Room-temperature elastic constants and low-temperature sound velocities for six nitrogen-alloyed austenitic stainless steels