From Micro to Nano Scales -Recent Progress in the Characterization of Nitrided Austenitic Stainless Steels

Abstract

In the frontier of materials science, understanding of materials has been in multiple scales from macro, micro, to atomic levels. This is attributed to the advanced instrumentations such as SEM, TEM, XPS, XRD, as well as several other spectroscopic and metallographic analyses. Fe-CrNi based austenitic stainless steels have a diverse range of modern applications ranging from biomedical prostheses in human bodies, food processing, to chemical engineering and nuclear power generation. The outstanding properties of the nitrided steels have attracted extensive research activities attempting to obtain a clear image on the structural characteristics of the structure, including nano-scale heterogeneity of the expanded austenite phase resulted from atomic-level chemical or electronic interactions in the alloying system. This paper provides a review on the structural characterization of nitrided austenitic stainless steels, with an emphasis on the latest experimental findings through the use of these sophisticated analytical tools. In the final section, several possible aspects of future studies are discussed.

From Austenitic Stainless Steel to Expanded Austenite-S Phase: Formation, Characteristics and Properties of an Elusive Metastable Phase

“…The low temperature surface treatment of austenitic stainless steel has been recognized as an important topic of surface engineering, and both briefs overviews, on general or on specific topics [17,31,[41][42][43][44][45][46], and more extended reviews [40,47,48] also have covered it recently. From the critical review of Dong [47], dating a decade ago, research has proceeded, new techniques have been employed to study the modified surface layers and the S phase, and new and interesting results have been reported, suggesting even the possibility that the S phase cannot be considered only a supersaturated solid solution of interstitial atoms in austenite.…”