Development of Compound Layer of Iron (Carbo)Nitrides during Nitriding of Steel

Abstract

The composition and phase constitution of a compound layer developing during gaseous nitriding was investigated at 853 K for three commercial steels (AISI 120, 4340 and 1090) and Armco iron. The compound layers were characterised by light optical microscopy, X-ray diffraction and electron probe microanalysis. The formation of the compound layer occurs along two distinct sequences: adc9de and/or a(h)de 2 dc9de 1 . The preferred sequence depends mainly on the chemical composition of steel and on the nitriding potential. SE/491Professor Ratajski

Nitrogen Availability Of Nitriding Atmosphere In Controlled Gas Nitriding Processes

“…It should be emphasized that in the case of the nitriding atmosphere obtained from the single component ingoing atmosphere of ammonia only, then the maximum nitrogen availability for a given nitriding potential is attained when the flow rate is slowest. The flow rates of ingoing atmospheres in the described processes are bound by the expression (8).…”

“…1). [8] Knowing the value of the dissociation rate to obtain the required value of the nitriding potential in the aNH 3 -cNH 3diss -type atmosphere, as well as the flow rate of that atmosphere, it is possible to use formula (9) to calculate what flow rate of a single component atmosphere is needed to obtain the same value of the nitriding potential: Expression (9) can be utilized to optimize ingoing atmospheres from the point of view of reduction of ammonia consumption in the designed nitriding process.…”

“…2a) [11]. • C [8] If the ingoing atmosphere is of the two -component type, with a composition of aNH 3 -bN 2 , then the function describing the dependence of the nitriding potential on the rate of dissociation can be written as:…”

Effect of nature of nitride phases on sliding wear of plasma nitrided sintered iron

“…According to the ternary Fe-N-C phase diagram [47,48], the ε phase can contain a considerably larger amount of carbon than γ 0 phase. Thus, in practice, the availability of carbon source (with CH 4 gas) will lead to a stabilisation of ε phase at the expenses of γ 0 phase [49][50][51]. When the solubility limit of nitrogen in the ferritic matrix is exceeded, γ 0 iron nitride nuclei can occur on the surface.…”

Discrimination between γ′‐Fe4N and ε‐Fe2–3N iron nitride compounds using PCA of Auger electron spectra

“…5,6 An accurate procedure was established for the quantification of nitrogen and iron, using well-defined pure compound references. This part of the Ł Correspondence to: I. Vandendael, Vrije Universiteit Brussel -Department of Metallurgy, Electrochemistry and Materials Science, Pleinlaan 2, B-1050 Brussels, Belgium.…”