Title Modeling of nitrogen and hydrogen stress assisted diffusion in plasma nitrided austenitic stainless steel /
Authors Galdikas, Arvaidas ; Moskalioviene, Teresa
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Is Part of E-MRS Spring Meeting 2018, June 18-22, 2018, Strasbourg, France.. Strasbourg : European Materials Research Society. 2018, L.12.7, p. 1
Keywords [eng] plasma nitriding ; stainless steel ; expanded austenite ; hydrogen ; stress assisted diffusion ; kinetic modeling.
Abstract [eng] The present work studies the internal stress assisted hydrogen and nitrogen diffusion in austenitic stainless steel (ASS) taking place during plasma nitriding using various mixtures of nitrogen and hydrogen. A systematic model for nitrogen transport in ASS that takes into account the hydrogen actions at steel surface and bulk, hydrogen and nitrogen adosbtion and diffusion with concentration dependent diffusion coefficient and stress interaction is proposed. It is shown, that the stress effect on the nitrogen flux should be considered in nitrided ASS because they are subjected to the large internal stress induced by the lattice expansion when hydrogen and nitrogen atoms intrude in the steel matrix. The variation of stress changes the diffusion force, which is the gradient of chemical potential, and affects the interstitials distribution and, consequently, have effects on the nitriding kinetics. Moreover, although these results are obtained from the ASS-nitrogen-hydrogen system, our conclusions can be extended to the diffusion problem of other interstitials in metal alloys. Finally, it was shown, that the addition of hydrogen in H2-N2 mixture flux with concentrations in the range ~ (30 - 40) % enhances nitrogen penetration into steel due to the hydrogen actions at steel surface. The obtained theoretical results are qualitatively consistent with the available experimental data.
Published Strasbourg : European Materials Research Society
Type Conference paper
Language English
Publication date 2018