Dependence of the nitriding rate of ferritic and austenitic substrates on the crystallographic orientation of surface grains; gaseous nitriding of Fe-Cr and Ni-Ti alloys

Akhlaghi, Maryam; Jung, Minsu; Meka, Sai Ramudu; Fonović, Matej; Leineweber, Andreas; Mittemeijer, E. J.

doi:10.1080/14786435.2015.1115906

Cited by 12 publications

(8 citation statements)

References 47 publications

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“…In work [26], we have shown that the values of the nitrogen penetration depths correlate well with the values of the anisotropic stress factor, X stress(hkl) , i.e., they are the lowest for (111), the deepest for (100) and intermediate for the other orientations. According to the experimental results in [6,8,[16][17][18][19], it can be concluded that the nitrogen surface concentration also increases in the order (111) < (110) < (100) for different crystallographic orientations. However, as we have shown in [26], if not taking into account the anisotropic nature of the adsorption, desorption and surface reactions, the calculated results show the opposite trend, i.e., the surface nitrogen content increases in the order (100) < (110) < (111).…”

Section: Resultsmentioning

confidence: 97%

“…One such phenomenon is that the lattice parameter expansion caused by interstitial nitrogen is crystallographically anisotropic. Typically, the lattice parameter a hkl , determined from the d-spacing of the (200) plane, is greater than that determined from the d-spacing of the (111), ( 220), (311) or (222) planes [6,8,[16][17][18][19]. Furthermore, the surface nitrogen content and the thickness of the case of the expanded austenite were shown to depend on the crystal orientation, i.e., an increase in the order (100) > (110) > (111) for different crystallographic orientations [6,8,[16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

“…Typically, the lattice parameter a hkl , determined from the d-spacing of the (200) plane, is greater than that determined from the d-spacing of the (111), ( 220), (311) or (222) planes [6,8,[16][17][18][19]. Furthermore, the surface nitrogen content and the thickness of the case of the expanded austenite were shown to depend on the crystal orientation, i.e., an increase in the order (100) > (110) > (111) for different crystallographic orientations [6,8,[16][17][18][19]. A recent explanation for this phenomenon involves the formation of stacking faults and high compressive residual stresses in the nitrided layer resulting in a highly distorted and disordered fcc structure [15].…”

Section: Introductionmentioning

confidence: 99%

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Crystallographic Orientation Dependence of Nitrogen Mass Transport in Austenitic Stainless Steel

Moskaliovienė

Galdikas

2020

Metals

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The lattice stress-induced diffusion of nitrogen and hydrogen in austenitic stainless steel, taking place during nitriding in nitrogen/hydrogen plasma, is analyzed in the presented work. Stress-induced diffusion has an anisotropic nature and depends on the orientation of the crystal lattice. However, during simulations, it is not enough to take into account only the anisotropy of stress-induced diffusion, since this leads to contradictory results when comparing with experimental data. The problem is the surface concentration of nitrogen. Processes on the steel surface such as adsorption, desorption and heterogeneous chemical reactions are also very important. In the presented work, it is shown that these surface processes also have anisotropic natures, and it is very important to take this anisotropy into account during simulations. The influence of anisotropic surface processes on austenitic steel nitriding is analyzed in this study. It is shown that the nitrogen diffusion is anisotropic due to the effects of the anisotropic stress gradient and the anisotropic effects on the steel surface.

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Section: Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Crystallographic Orientation Dependence of Nitrogen Mass Transport in Austenitic Stainless Steel

Moskaliovienė

Galdikas

2020

Metals

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“…Many experiments show that the thickness of expanded austenite phase as well as nitrogen penetration depth depend on the crystal orientation and increase in the order (111) < (110) < (100) for different orientations [6,8,[17][18][19][20]. The same order of crystalline orientations follows the nitrogen concentration on the surface.…”

Section: Introductionmentioning

confidence: 99%

“…It was shown the existence of short range ordering of Cr and N atoms takes place [33,34]. High content of nitrogen penetrating the volume of austenite has been attributed to the trapping of nitrogen at octahedral interstitial sites, by alloying element atoms dissolved in the matrix with high affinity for N such as Cr [18,34]. The role of Cr has been investigated to have pointed to "trapping and detrapping" diffusion of nitrogen [35].…”

Section: Introductionmentioning

confidence: 99%

The Anisotropic Stress-Induced Diffusion and Trapping of Nitrogen in Austenitic Stainless Steel during Nitriding

Galdikas

Moskaliovienė

2020

Metals

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Plasma nitriding of austenitic stainless steels at moderate temperatures is considered in the presented work. The anisotropic aspects of stress-induced diffusion and influence of nitrogen traps are investigated by kinetic modeling based on rate equations. The model involves diffusion of nitrogen in the presence of internal stress gradients induced by penetrating nitrogen as the next driving force of diffusion after the concentration gradient. The diffusion equation takes into account the fact that nitrogen atoms reside in interstitial sites and in trapping sites. Stress-induced diffusion has an anisotropic nature and depends on the crystalline orientation while trapping–detrapping is isotropic. The simulations are done considering the synergetic effects of both mechanisms and analyzing the properties of both processes separately. Theoretical curves are compared with experimental results taken from the literature. Good agreement between simulated and experimental results is observed, and gives the possibility to find real values of parameters needed for calculations. The nitrogen depth profile shapes, the dependences of nitrogen penetration on nitriding time and on diffusivity, are analyzed considering crystalline orientation of steel single crystal.

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Alloying Element Nitride Development in Ferritic Fe-Based Materials Upon Nitriding: A Review

Steiner

Mittemeijer

2016

J. of Materi Eng and Perform

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With the aim of achieving a better understanding of the nitriding process of iron-based components (steels), as applied in engineering practice, the theoretical background and experimental observations currently available on the crystallographic, morphological, and compositional properties of the nitride precipitates in nitrided model binary and ternary, ferritic Fe-based alloys are summarily presented. Thermodynamic and kinetic considerations are employed in order to highlight their importance for the nitriding reaction and the resulting properties of the nitrided zone, thereby providing a more fundamental understanding of the nitriding process.

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Dependence of the nitriding rate of ferritic and austenitic substrates on the crystallographic orientation of surface grains; gaseous nitriding of Fe-Cr and Ni-Ti alloys

Cited by 12 publications

References 47 publications

Crystallographic Orientation Dependence of Nitrogen Mass Transport in Austenitic Stainless Steel

Crystallographic Orientation Dependence of Nitrogen Mass Transport in Austenitic Stainless Steel

The Anisotropic Stress-Induced Diffusion and Trapping of Nitrogen in Austenitic Stainless Steel during Nitriding

Alloying Element Nitride Development in Ferritic Fe-Based Materials Upon Nitriding: A Review

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