Control of the phase composition and nitrogen content in the nitride layer in the nitriding of the steel 38Kh2MYuA

Lakhtin, Yu. M.

doi:10.1007/bf01153864

Cited by 5 publications

(4 citation statements)

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“…Decreasing of K N 2 values caused formation of thinner white layer at constant temperature of second stage nitriding. Aluminium within the samples promotes intercrystalline diffusion of nitrogen and alloys the γ -phase (Fe 4 N) in form of (Fe, Al) 4 N. γ phase grows preferentially in the "whiskers" forming through the grain boundaries (Table I) [9,12]. Figure 2 shows the XRD patterns of the samples, gas nitrided at 500…”

Section: Resultsmentioning

confidence: 99%

“…Under such conditions, the structure of the nitrided layers is such that the top nitride layer, known as the compound layer, is composed mainly of γ -Fe 4 N and ε-Fe 2−3 N, as well as nitrides of alloying elements, as with aluminium-enriched γ -phase of (Fe, Al) 4 N, which lies below the ε-phase and penetrates into the depth of the metal, along the grain boundaries. The layer beneath the compound layer is known as the so-called diffusion layer, which consists mainly of interstitial atoms in solid solution and fine, coherent nitride precipitates, when the solubility limit is reached [9,10].…”

Section: Introductionmentioning

confidence: 99%

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Effect of Double Stage Nitriding on 34CrAlNi7-10 Nitriding Steel

et al. 2017

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In this study, effect of double stage gas nitriding of 34CrAlNi7-10 steel was analyzed. Nitriding processes were carried out in two stages. in the first stage, samples were nitridied at 500• C for 10 h and then in second stage nitriding process was continued at 530 and 550• C for 20 h. During both stages, the nitrogen activity on surface was controlled by the nitriding potential, which is a thermodynamical control parameter for controlled gas nitriding process. The nitriding potential was kept constant, at value of 10, during the first stage and was varied in the range of 3.2-0.2, for both nitriding temperatures, in the second stage. The presence of nitrides, formed on the surface of test materials was determined by XRD analysis technique. The morphology of nitrided layer was studied by optical microscopy. The microhardness of the surfaces of nitrided samples in HV1 was between 955 and 1029. The measurements have shown that the thickness of the compound layer (white layer) has varied between 6.85-23.90 µm and that the growth of the white layer and microhardness gradient were strongly affected by the nitriding potential and the temperature. Diffusion depths as Nht(HV) for Vickers Hardness were determined and compared.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Double Stage Nitriding on 34CrAlNi7-10 Nitriding Steel

et al. 2017

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“…M. Lakhtin in [ 10] consists of using waste nitriding gases. For this purpose the gas outlet of one furnace is connected to the gas inlet of another one given that the dissociation of ammonia in the first furnace does not exceed 40-45% [11][12] . Distribution of the microhardness over the thickness of the layer in specimens of steel 40Kh after saturation at 570~ for 4, 6, and 12 h in an atmosphere of 50% NH 3 + 50% natural gas.…”

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confidence: 99%

Development of nitriding in Russia. The third period (1960–1980): Low-temperature thermochemical treatment (LTTCT)

Bannykh¹,

Zinchenko²,

Prusakov³

et al. 2000

Met Sci Heat Treat

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The beginning of the third period of nitriding coincided in time with the change in the concept of the choice of materials for fabricating parts in world practice, namely, with the intense transition to the use of materials in a metastable state and a marked progress in the use of synergism of mechanical properties and extreme technologies that provide the creation of highly nonequilibrium structures and their self-organization under nonequilibrium conditions. A new direction known as surface engineering has appeared on the basis of the concept of the leading role of the surface and its properties (rather than the volume properties) in the structural strength and service characteristics of parts. The surface treatment began to predominate over the volume heat treatment. Preference was given to machine parts with a tough core and a hardened surface layer. G. N. Dubinin put forward a structure-energy hypothesis of the effect of the diffusion layer on the volume properties of alloys [1] in accordance with which the diffusion saturation of the surface with atoms causes a decrease in the density of vacancies in the diffusion zones and an increase in the energy of interatomic bonding. This creates obstacles for the outcome of the dislocations to the surface when the metal is loaded by a mechanical force and changes the kinetics of the nucleation and growth of microcracks on the surface, increasing the volume strength under conditions of static and dynamic loading at conventional and high temperatures [2 -5].The rapid development of the processes of chemical heat treatment caused an increase in the volume of gas nitriding. Nitriding in Russia in the 1960s mainly progressed due to the creation of new saturating media. The aim consisted of removing or restricting the disadvantages of the process determined in the previous years, i.e., the high brittleness of the surface layer, the long saturation time, the necessity of using predominantly alloy steels.

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“…Nevertheless, mechanisms due to aluminium are not clear [3]. After such a treatment, generally a thin compound layer known as white layer consists of ε and γ iron nitrides together on the surface where aluminium enriched γ -phase of (Fe,Al) 4 N lies below the ε-phase and * corresponding author; e-mail: ialtinsoy@sakarya.edu.tr penetrates into the depth of the metal along grain boundaries [4].…”

Section: Introductionmentioning

confidence: 99%

Gas Nitriding Behaviour of 34CrAlNi7 Nitriding Steel

Ibrahim

Önder²,

Efe

et al. 2014

Acta Phys. Pol. A

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In this study, gas nitriding behavior of 34CrAlNi710 steel was investigated. Single stage processes were carried out at 500• C, 520• C and 540• C for 10, 20, 30 h, respectively. Nitrogen activity on surface was controlled by the nitriding potential KN which is known as thermodynamical control parameter for controlled gas nitriding process. The presence of nitrides formed on surface of test material was determined by X-ray diraction analysis technique. The morphology of nitrided layer was studied by optical microscope. The microhardness of surface of nitrided sample in HV1 was observed between 975 and 1132. Choosing the right nitriding potentials for each temperature, which give the same nitrogen concentration and activity on surface by using the Lehrer diagram, showed that all the samples had almost the same surface roughness of Ra = 0.280.32 µm after gas nitriding cycles. The measurements showed that the white layer thickness varies between 4.38 µm and 28.80 µm and the growth of the layer was strongly aected by process time and temperature. Diusion depths as Nht (HV) for each experiment were determined and compared.

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Control of the phase composition and nitrogen content in the nitride layer in the nitriding of the steel 38Kh2MYuA

Cited by 5 publications

References 1 publication

Effect of Double Stage Nitriding on 34CrAlNi7-10 Nitriding Steel

Effect of Double Stage Nitriding on 34CrAlNi7-10 Nitriding Steel

Development of nitriding in Russia. The third period (1960–1980): Low-temperature thermochemical treatment (LTTCT)

Gas Nitriding Behaviour of 34CrAlNi7 Nitriding Steel

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