Diffusion profiles after nitrocarburizing austenitic stainless steel

Wu, Dee H.; Ge, Yindong; Kahn, H.; Ernst, F.; Heuer, A. H.

doi:10.1016/j.surfcoat.2015.08.048

Cited by 25 publications

(23 citation statements)

References 32 publications

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“…This can be pictured as follows: the carbon atoms are pushed into the lower part of the hardened layer by the nitrogen atoms, resulting in a low carbon level in the N-enriched layer. It is possible to observe the presence of a small amount of nitrogen and a large amount of carbon in the diffusion zone, but both amounts decrease along the chemical composition line until they reach the chemical composition of the sample core 14 .…”

Section: Resultsmentioning

confidence: 99%

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Morphology of the DIN 100Cr6 Case Hardened Steel after Plasma Nitrocarburizing Process

Fontes¹,

Scheid

Machado

et al. 2019

Mat. Res.

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Nitrocarburizing is considered one of the most important thermochemical treatments for surface modification of metallic materials and involves the simultaneous diffusion of nitrogen and carbon onto the surface. Understanding and controlling the formation of the nitrocarburized layer have considerable industrial interest due to the improvements regarding wear, fatigue, and corrosion resistances. DIN 100Cr6 steel samples were treated by plasma nitrocarburizing for two hours, with two treatment temperatures (550 and 600°C) and four methane concentrations in the gas mixture composition (0, 1.0, 1.5, and 2.0%). SEM and XRD analyses, and wear resistance tests were used to characterize the samples. Results showed that the treatment temperature and atmosphere composition had considerable influence on the compound layer morphology. For nitrided samples the compound layer consists of γ'-Fe 4 N phase, and the presence of carbon in the gas mixture helps stabilize the ɛ-Fe 2-3 N phase. Higher CH 4 concentration in the treatment atmosphere improve the sample superficial wear resistance.

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Section: Resultsmentioning

confidence: 99%

“…The process modifies the alloy surface proprieties due to the formation of crystalline phases such as iron nitrides and/or carbonitrides 4 , improving considerably the corrosion 5 and wear resistances 6-12 . Recently there have been a number of reports dealing with the nitrocarburizing of steels 6,7, [13][14][15] .…”

Section: Introductionmentioning

confidence: 99%

Morphology of the DIN 100Cr6 Case Hardened Steel after Plasma Nitrocarburizing Process

Fontes¹,

Scheid

Machado

et al. 2019

Mat. Res.

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“…En cuanto a los espesores de la capa nitrocarburada se sitúan entre 29 y 50 µm. Estos valores son mucho menores que los obtenidos en el caso del acero AISI 4340 con tiempos semejantes lo que se debe al alto contenido en cromo del AISI 347, que dificulta la difusión del nitrógeno y aumenta la cantidad de nitruros precipitados (Wu et al, 2015) La microestructura obtenida en todas las muestras del acero AISI 4340 nitrocarburado ( Fig. 1a) es muy similar: en la parte más externa, se observa una capa de óxidos de poco espesor y, por debajo de ésta, una capa de combinación o capa blanca formada por Figura 1.…”

Section: Caracterización Microestructuralunclassified

Estudio comparativo de la nitrocarburación de los aceros AISI 4340 y AISI 347 mediante el proceso Tenifer-QPQ®

Bellas¹,

Castro²,

Mera³

et al. 2019

REVMETAL

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Este trabajo estudia las diferencias microestructurales y tribológicas de las capas formadas durante la nitrocarburación ferrítica del acero aleado AISI 4340 y la nitrocarburación austenítica del acero inoxidable estabilizado AISI 347. Las muestras se sometieron a distintos tiempos de inmersión en un baño de nitrocarburación (60, 75, 90, 105 y 120 min) a 580 ºC. Posteriormente se sometieron a un proceso de oxidación a 480 ºC para formar una capa de Fe3O4. Los estudios de la microestructura de la capa nitrocarburada se realizaron por microscopía electrónica de barrido (SEM), espectroscopía de dispersión de energías (EDS) y difracción de rayos X (XRD). Se estudió el desgaste y el coeficiente de fricción de las muestras nitrocarburadas y las muestras no tratadas mediante el ensayo pink-on disk. Los resultados muestran tres zonas bien diferenciadas en el acero AISI 4340: una capa de óxidos externa, una capa blanca o de combinación y zona de difusión. Sin embargo, no se detectó la presencia de la capa de combinación en el acero AISI 347. En ambos aceros, el coeficiente específico de desgaste (k) de las muestras nitrocarburadas fue aproximadamente treinta veces menor que el de las muestras de referencia.

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“…[8][9][10] The thickness of the carbon expanded austenite and the nitrogen expanded austenite in a nitrocarburizing experiment is comparable to the respective carburizing or nitriding experiment. 6,8 Irrespectively of the processing sequence (simultaneous nitrocarburizing, carburizing followed by nitriding, nitriding followed by carburizing) the nitrogen expanded austenite occupies the surface and carbon expanded austenite occupies the deeper regions. 6 The key challenge lies in the complex interplay of different physical phenomena.…”

Section: Introductionmentioning

confidence: 99%

“…6,8 Irrespectively of the processing sequence (simultaneous nitrocarburizing, carburizing followed by nitriding, nitriding followed by carburizing) the nitrogen expanded austenite occupies the surface and carbon expanded austenite occupies the deeper regions. 6 The key challenge lies in the complex interplay of different physical phenomena. The usual strategy of applying ex-situ treatments and analyzing the specimen at different stages 3,11,12 requires a favorable selection of heat treatment stages; otherwise, important information might be lost.…”

Section: Introductionmentioning

confidence: 99%

In-situ kinetics study on the growth of expanded austenite in AISI 316L stainless steels by XRD

Balogh-Michels

Faeht

Kleiner

et al. 2017

Journal of Applied Physics

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The formation of expanded austenite in Cr-Ni austenitic stainless steels like AISI 316L is not completely understood despite its technological relevance. In this work, we present an in-situ X-ray diffraction study on the growth kinetics of the expanded austenite. We applied a lowtemperature nitrocarburizing treatment using a mixture of NH 3 , N 2 , H 2 , and C 2 H 4 gases at atmospheric pressures in a novel and custom built chamber attached to a Bruker D8 Advance diffractometer. The nitrocarburizing temperature was varied between 340 and 440 C, and the possible effects of the gas amount were also tested. The thickness of the growing layer was determined from the shrinkage of the unmodified austenite peak. The growth rate coefficient was calculated using the linear-parabolic equation. The resulting coefficients follow the Arrhenius law with the activation energy of 165 6 12 kJ/mol. This value is in good agreement with the diffusion activation energy for heavy interstitials like carbon and nitrogen. The expanded austenite peak was modelled by a multilayer approach, where each 0.5 lm sublayer has a constant lattice parameter. The lattice expansion is analyzed as a function of the Boltzmann-variable (g ¼ 0.5 Â t À1/2). The expanded austenite layer in this metric has a constant width. Furthermore by rescaling with the lattice expansion of the first sublayer, it is possible to create a scale-independent master curve. These findings indicate that thickening of the expanded austenite is purely diffusion controlled, while the extent of strain is set by the uptake rate of the gas atoms. Published by AIP Publishing.

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Diffusion profiles after nitrocarburizing austenitic stainless steel

Cited by 25 publications

References 32 publications

Morphology of the DIN 100Cr6 Case Hardened Steel after Plasma Nitrocarburizing Process

Morphology of the DIN 100Cr6 Case Hardened Steel after Plasma Nitrocarburizing Process

Estudio comparativo de la nitrocarburación de los aceros AISI 4340 y AISI 347 mediante el proceso Tenifer-QPQ®

In-situ kinetics study on the growth of expanded austenite in AISI 316L stainless steels by XRD

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