Papers by Keyword: Nitrogen Austenite

Abstract: The specific features of atmospheric nitrogen surface nitriding of cold-rolled foils (the value of the coherent-scattering region is 10 nm) from stainless maraging steels after hardening in a confined space containing air are considered. Thermodynamic evaluation of the probability of influence caused by the confined space air on the phase transformations and solubility of the atmospheric nitrogen shows that the surface modification takes place in two stages: at the first stage, oxidation dominates; and at the second stage, predominantly the nitrogen absorption by the surface takes place. While changing, the nitrogen solubility reaches the maximum in the range of 10 – 22 % of Cr and has the largest values at the air pressure in the range of 0.001 – 0.04 MPa. Based on the nitrogen solubility diagrams, optimal conditions for the nitrogen austenite formation without the formation of nitrides are established. The developed method for nitriding allows the formation of nitrogen austenite layer of about 20 μm in thickness in the surface of nanostructured maraging steels without deteriorating the surface electrochemical properties.

Abstract: This paper presents investigations of nitrided cases after the glow-discharge nitriding process. The nitrided cases were obtained by using a different chemical composition of gas mixture at the temperature of 450^OC. The glow-discharge nitriding process was carried out on austenitic stainless steel, grade of steel X5CrNi18-10. The chemical composition and phase identification of the nitrided cases were examined by using the glow-discharge optical emission spectrometry (GD-OES) and X-ray diffractometry (XRD)

Abstract: The paper analyzes the magnetic properties and stability of austenite, athermal martensite, and deformation martensite that form in Ni27Ti2AlMoNb steel subjected to glow discharge assisted nitriding, and also of nitrogen austenite (S phase with various lattice constants) which occurs when the nitriding process is conducted below the temperature A_s. The analysis of these structural components and their morphology was performed using a magnetic force microscope (MFM), whereas the phase composition of the nitrided layers produced on this steel was determined by X-ray diffraction.