Structures of some 17% Cr(Mn, N) stainless steels

A study of the structures of 17 wt.% Cr(Mn, N) stainless steels has been made with the help of X-ray diffraction, optical and electron microscopic techniques. It reveals that these steels become entirely austenitic when 10% manganese or more is present in a steel that contains about 0.4% nitrogen and 0.1% carbon. No precipitation other than the grain boundary carbides is observed on prolonged exposure to high temperatures.
Below 10% manganese, an unstable austenite is formed which undergoes a series of transformations at different temperatures. The mode of these transformations has been studied in detail from 1400 to 700‡C. A possible mechanism of transformation is discussed.