Stress induced and concentration dependent diffusion of nitrogen in plasma nitrided austenitic stainless steel

Moskaliovienė, Teresa; Galdikas, Arvaidas

doi:10.1016/j.vacuum.2012.03.026

Cited by 35 publications

(21 citation statements)

References 44 publications

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“…Considering further surface hardness after the DPN process compared with the UPN may be told as nitrided layer in the DPN type has more hardness than that of the UPN. The similar behavior is seen in the previous works [18,25,27], where conducting mechanical surface treatments such as shot peening or mechanical attrition before nitriding creates a thicker nitrided layer with further surface hardness in austenitic stainless steels.…”

Section: Resultssupporting

confidence: 87%

“…4, the thickness of expanded austenitic layer in the UPN is about 12 lm, while in the DPN is about 20 lm. Increase in the thickness of nitrided layer can be attributed to the increase of crystalline defect density such as grain boundaries, mechanical twins, martensitic interfaces, and high-strained crystalline lattice, which are suitable paths for the rapid diffusion of nitrogen [8,26,27]. Therefore, conducting the deep rolling process prior to the nitriding can enhance the thickness of nitrided layer, due to the increase of nitrogen diffusion in surface layers.…”

Section: Resultsmentioning

confidence: 99%

“…Three models have been suggested to illustrate the nitrogen diffusion in austenitic stainless steels [27]: (1) the trapping-detrapping model, (2) the concentration-dependent diffusion model based on Fick's laws and (3) the model combined of those two models. In the trappingdetrapping model, chromium atoms play a crucial role via a chemical bonding effect where Cr atoms form trap sites for N [28].…”

Section: Resultsmentioning

confidence: 99%

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Influence of surface nano/ultrafine structure formed via pre-deep rolling process on the plasma nitriding characteristics of the AISI 316L stainless steel

2017

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Influence of deep rolling prior to plasma nitriding on microstructure and hardness of the AISI 316L stainless steel was investigated in this paper. Deep rolling using 'ball-point' tool was conducted on the 316L stainless steel bar at multiple passes. Then, plasma nitriding was performed on the as-received and deep-rolled kinds at 450°C temperature for 5 h. Structural characterisation was done using optical microscope, field emission scanning electron microscope, feritscope, X-ray diffractometer, and glow discharge optical emission spectroscope as well as hardness measurement by a Vickers micro-hardness tester at 0.1 kgf. An ultrafine structure and a nitrogen-rich layer were, respectively, formed on the rolled and nitrided surfaces. Surface hardness was increased from 210 up to 450, 670 and 1050 HV 0.1 after the rolling, nitriding, and rollingnitriding processes, respectively. Thickness of the nitrided layer was increased from 12 to 20 lm and diffusion depth of nitrogen from 12 to 25 lm via conducting the deep rolling before the nitriding process. The rolling-nitriding process was resulted in rising of nitrogen concentration by a factor of about 3 at near-surface regions.

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Section: Resultssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Influence of surface nano/ultrafine structure formed via pre-deep rolling process on the plasma nitriding characteristics of the AISI 316L stainless steel

2017

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“…Simulation models like these do not account for the development of residual stress and its influence on the developing concentration-depth profiles. Although the consideration of residual stress was suggested to enhance nitrogen diffusion in expanded austenite, and demonstrated to be able to enhance the case depth by a factor two when the surface concentration was constant [14], further mathematical implementation has so far been pragmatic, assuming an unphysical linear relation between composition and stress and a continuously decreasing diffusion coefficient [36], which obviously is in conflict with the experimentally determined diffusion coefficient for nitrogen in expanded austenite. In the present work the actual lattice expansion of expanded austenite was taken into account and mechanical equilibrium considerations were used to estimate the stress.…”

Section: Evolution Of Composition and Stress-depth Profilesmentioning

confidence: 99%

Modelling the evolution of composition-and stress-depth profiles in austenitic stainless steels during low-temperature nitriding

Jespersen¹,

Hattel²,

Somers³

2016

Modelling Simul. Mater. Sci. Eng.

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Nitriding of stainless steel causes a surface zone of expanded austenite, which improves the wear resistance of the stainless steel while preserving the stainless behavior. During nitriding huge residual stresses are introduced in the treated zone, arising from the volume expansion that accompanies the dissolution of high nitrogen contents in expanded austenite.An intriguing phenomenon during low-temperature nitriding is that the residual stresses evoked by dissolution of nitrogen in the solid state, affect the thermodynamics and the diffusion kinetics of nitrogen dissolution. In the present paper solid mechanics was combined with thermodynamics and diffusion kinetics to simulate the evolution of composition-depth and stress-depth profiles resulting from nitriding. The model takes into account a composition-dependent diffusion coefficient of nitrogen in expanded austenite, short range ordering (trapping) of nitrogen atoms by chromium atoms, and the effect of composition-induced stress on surface concentration and diffusive flux. The effect of plasticity and concentrationdependence of the yield stress was also included.

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“…В литературе приводятся примеры моделирования этого процесса, однако они используют для оценки напряжений известные решения задач для гомогенных сред [11]. В работах [12][13][14] предложены модели процесса азотирования, учитывающие уси-ление диффузии за счет внутренних напряжений, возникающих в поверхностном слое с вы-сокой концентрацией внедренных атомов азота в крупнокристаллическую аустенитную сталь, которые, однако, не учитывают изменения напряженного состояния в градиентном по-верхностном слое при деформационном наноструктурировании. Делаются попытки учета при моделировании низкотемпературного плазменного азотирования анизотропии коэффи-циентов диффузии для различных кристаллографических ориентировок аустенитной стали [15].…”

Section: Introductionunclassified

Mathematical modelling of plasma nitriding of austenitic stainless steel

Спевак¹,

Нефедова²,

Макаров³

et al. 2015

DREAM

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34, Ekaterinburg, Russian Federation. Tel.: +7 (343) 375 35 92; fax: 3745330 Two mathematical models of diffusion are discussed as applied to the description of ion nitriding of austenitic stainless steel in electron beam plasma. One model is based on the assumption of the diffusion coefficient dependent on concentration, and this corresponds to the nonlinear boundary value problem of diffusion. The other model takes into account the effect of internal stresses, occurring in the surface layer and induced by introduced nitrogen atoms, on the diffusion process, and this leads to the inhomogeneous boundary value problems of diffusion. Algorithms for solving the boundary value problems are proposed, which are based on the boundary element method. Model examples have been solved to illustrate the functioning of the algorithms. Gavrilov N.V., Men'shakov A.I. A source of broad electron beams with a self-heated hollow cathode for plasma nitriding of stainless steel. Instruments and Experimental Techniques, 2011, vol. 54, no. 5, pp. 732-739. DOI: 10.1134/S0020441211050046. 4. Gavrilov N.V., Menshakov A.I. Low-temperature nitriding of stainless steel in electron beam plasma at 400 ºС. Fizika i khimiya obrabotki materialov, 2012. no. 5, pp. 31-36. (In Russian). 5.Lo K.H., Shek C.H., Lai J.K.L. Recent developments in stainless steels. Materials Science and Engineering: R: Reports, 2009, vol. 65, iss. 4-6, pp. 39-104. DOI: 10.1016/j.mser.2009. Laleh M., Kargar F., Velashjerdi M. Low-Temperature Nitriding of Nanocrystalline Stainless Steel and Its Effect on Improving Wear and Corrosion Resistance. Journal of Material Engineering and Performance, 2013, vol. 22, iss. 5, pp. 1304-1310. DOI: 10.1007.Makarov A.V., Skorynina P.A., Osintseva A.L., Yurovskikh A.S., Savray R.A. Improving the tribological properties of austenitic steel 12Kh18N10T by nanostructuring frictional treatment.

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Stress induced and concentration dependent diffusion of nitrogen in plasma nitrided austenitic stainless steel

Cited by 35 publications

References 44 publications

Influence of surface nano/ultrafine structure formed via pre-deep rolling process on the plasma nitriding characteristics of the AISI 316L stainless steel

Influence of surface nano/ultrafine structure formed via pre-deep rolling process on the plasma nitriding characteristics of the AISI 316L stainless steel

Modelling the evolution of composition-and stress-depth profiles in austenitic stainless steels during low-temperature nitriding

Mathematical modelling of plasma nitriding of austenitic stainless steel

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