Study of expanded austenite formed in plasma nitrided AISI 316L samples, using synchrotron radiation diffraction

Campos, Marcelo; Souza, Solange de; Martinez, L.G.; Olzon-Dionysio, M.

doi:10.1590/1516-1439.285914

Cited by 6 publications

(6 citation statements)

References 25 publications

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“…Still for the sample P6, it is interesting to compare the present results for C N (corresponding to α =0.00861 Å/ at.% N) calculated for the θ-2θ geometry with the previous one for the thicker sample 18 . In the preceding case, the decomposition of the γ N peaks in subpeaks was used in order to consider the nitrogen gradient profile and the results were between 1.1 and 3.1° for distortion and between 12±3 and 35±3 for C N .…”

Section: Drxmentioning

confidence: 66%

“…With respect to Fig 6 and 7, as the penetration depth of the synchrotron radiation 18 is greater than the thickness for all of the samples, the austenite peaks are present in all of the XRD patterns in Fig 6, but not in Fig 7, where the measurement depth was 0.63 µm, which is smaller than the thickness for all the samples. All the nitrided samples show the expanded austenite peaks, which are broader and shifted to lower diffraction angles, when compared to the correspondent austenite peaks.…”

Section: Drxmentioning

confidence: 82%

“…Therefore, for a preliminary analysis, as is our intention here, it is almost impossible to discuss the presence of these nitrides in the samples through these X-ray diffractograms. If a more realistic analysis is required, the decomposition of the γ N peaks in subpeaks, in order to consider the nitrogen content (C N ) gradient across the nitrided layer is necessary and consequently the nitrides are detected 18 . Despite its limitations, this preliminary DRX data treatment can provide us with consistent information to interpret minimally the corrosion results, which indicated the P6 sample as the most resistant to corrosion.…”

Section: Drxmentioning

confidence: 99%

“…As was said before, in order to compare the present results with the previous one, the DRX data ( Fig 6) were analyzed in the same way 18 , although this treatment presents major limitations, which are discussed below. The results for distortion of the triclinic structure (η) and the nitrogen content C N are shown in Table 7.…”

Section: Drxmentioning

confidence: 99%

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Influence of the Gas Pressure of Plasma Nitriding on the Structural, Mechanical and Tribological Surface Properties of AISI 316L

et al. 2019

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In this paper, the influence of gas nitriding (80% H 2-20% N 2) pressure (between 3 and 7 Torr) on the modification of surface properties of AISI 316L stainless steel is examined. The structural, mechanical, tribological and electrochemical properties of the layer produced in disk samples were studied. The samples' characteristics were determined by scanning electron microscopy, X-ray diffraction, electrochemical potential curves, microhardness, roughness and wear tests. When pressure increases, the microhardness, elasticity and thickness also increase. The maximum thickness of the nitrided layer was 6.4 µm, the hardness reached 2200 HV 0.0036 and the mass loss decreased until 1% relatively to the unnitrided sample. The X-ray diffractograms showed the presence of the expanded austenite in all the samples. The correlation between these diffractograms and the corrosion results corroborate to the most recent previous conclusions of our systematic study, which evince the interconnection between the improvement of the corrosion resistance and the presence of nitrides on the top of the nitrided layer. More significant presence of such nitrides was observed for the sample nitrided at 6 Torr, whose corrosion performance was better than for the other samples. This pressure seems to be the most indicated to improve the properties under study. Moreover, the results verified not only that the sample geometry is an important factor for enhancing these properties but also that the border effect, which causes the rings on the disk border, depends on the pressure, but not on temperature or time from the plasma nitriding process.

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Section: Drxmentioning

confidence: 66%

Section: Drxmentioning

confidence: 82%

Section: Drxmentioning

confidence: 99%

Section: Drxmentioning

confidence: 99%

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Influence of the Gas Pressure of Plasma Nitriding on the Structural, Mechanical and Tribological Surface Properties of AISI 316L

et al. 2019

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“…In addition, pitting corrosion normally occurs at the sites of local heterogeneities as a consequence of local breakdown of adherent passive film in chloride (Cl -) environments [3][4][5][6][7] . The hardness and tribological properties of austenitic stainless steels can be improved by enriching the near-surface region using low temperature plasma nitriding [8][9][10][11][12] . However, direct current plasma nitriding (DCPN) technology, which has been used most frequently at present, is subjected to edge effect and surface arcing 13 .…”

Section: Introductionmentioning

confidence: 99%

Enhancement of Pitting Corrosion Resistance of Austenitic Stainless Steel Through Deposition of Amorphous/Nanocrystalline Oxy-nitrided Phases by Active Screen Plasma Treatment

Qiu

et al. 2018

Mat. Res.

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In this research, AISI 304 austenitic stainless steels were efficient treatment using active screen plasma oxy-nitriding technique. The modified layers were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopes, and atomic force microscopy. In addition, the pitting corrosion resistances of untreated and oxy-nitrided samples were analyzed by polarization method in 3.5 wt.% NaCl solution. The results showed that a duplex-layer consisting of a deposition layer and a diffusion layer (including CrN+α phase and nitrogen expanded austenite phase) was generated. Special concern has been given to the formation of an amorphous top layer for the deposition of nano sized oxy-nitrides. It believed that the deposition layer of oxy-nitrides formed on steel surface during active screen plasma oxy-nitriding that lead to improved corrosion resistance of AISI 304 austenitic stainless steel, so that the pitting corrosive attack can be avoided.

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New Approach for Plasma Nitrocarburizing of Stainless Steels by a Modified Reactor Configuration Using a Plasma‐Activated Solid Carbon Precursor

M. Jafarpour,

Dalke,

Biermann

2024

steel research int.

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Stainless steel surfaces can be modified using plasma‐assisted thermochemical treatments to improve properties like hardness, wear, and pitting corrosion resistance. To specifically adjust the desired properties, a precise control of the produced treatment‐relevant gas species with regard to their type and concentration is essential. This requires the adjustment of the parameters for the generation of the gas species, being independent from heating parameters, as well as their real‐time measurement. Therefore, this study presents the use of a plasma‐activated solid carbon precursor in a cold‐wall reactor using active screen technology and in a modified hot‐wall reactor during plasma nitrocarburizing of austenitic stainless steel. In addition, the modified hot‐wall reactor combined with a compact laser‐based absorption spectroscopy sensor for real‐time monitoring and concentration evaluation of in‐site generated gas species. It is shown that implementing a plasma‐activated solid carbon precursor in a modified hot‐wall reactor enables adjustable generation of C‐containing gas species, particularly HCN, with high production yield by an independent power management. Therefore, HCN is produced independent from heating while the limitations arising during active screen technology using a carbon screen are avoided. The presented technological development thus opens up new possibilities for better control of the plasma nitrocarburizing treatments of steels.

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Study of expanded austenite formed in plasma nitrided AISI 316L samples, using synchrotron radiation diffraction

Cited by 6 publications

References 25 publications

Influence of the Gas Pressure of Plasma Nitriding on the Structural, Mechanical and Tribological Surface Properties of AISI 316L

Influence of the Gas Pressure of Plasma Nitriding on the Structural, Mechanical and Tribological Surface Properties of AISI 316L

Enhancement of Pitting Corrosion Resistance of Austenitic Stainless Steel Through Deposition of Amorphous/Nanocrystalline Oxy-nitrided Phases by Active Screen Plasma Treatment

New Approach for Plasma Nitrocarburizing of Stainless Steels by a Modified Reactor Configuration Using a Plasma‐Activated Solid Carbon Precursor

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