Atomistic diffusion mechanism of rare earth carburizing/nitriding on iron-based alloy

You, Yang; Yan, Jiuchun; Yan, Mufu

doi:10.1016/j.apsusc.2019.04.005

Cited by 23 publications

(6 citation statements)

References 39 publications

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“…in iron solid solution based on first principles calculations, big positive values were obtained for the substitution energy of a RE atom in bcc Fe and the sum of the Fe atoms’ relaxations around RE atom. [ 27,28 ] The lattice distortion level is dependent on the difference of atomic size between the foreign atom and iron atom. In our work, the minor addition of Ce in Fe–Cr–Ni‐based 13Cr steel caused that the lattice parameter of substitutional solid solution α(Fe) increased by 0.2%.…”

Section: Resultsmentioning

confidence: 99%

Structure and Property Modulations of 13Cr Stainless Steel Through Microgravity Solidification and Minor Ce Addition

Ruan

Wang

Wei

2021

steel research int.

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Both rare‐earth doping and microgravity solidification processing bring significant influences upon the structure formation and mechanical properties of various alloys. Herein, the microstructure and performance of 13Cr martensitic stainless steel are modulated by adding minor Ce content and microgravity solidification by means of drop tube technique. The lattice structure of constituent phase α(Fe) is deformed evidently by microgravity solidification, and the lattice parameter variation is 1.8 times of that caused by Ce addition. The microstructures of this steel processed by arc melting consist of lath‐shaped martensites and a few feather‐shaped bainites whose volume fraction increases with the Ce content. The bainite is replaced by ferrite in the rapidly solidified microstructure of 13Cr steel under microgravity condition. Although both microgravity solidification and Ce addition induce the microstructure refinement and inclusion spheroidization, the former effect plays the dominant role. The compressive properties and microhardness decrease moderately with Ce addition due to the slight increase in bainite, however, the microgravity solidification brought the hardening effect and thus the microhardness of the steel droplets increases with undercooling.

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Section: Resultsmentioning

confidence: 99%

Structure and Property Modulations of 13Cr Stainless Steel Through Microgravity Solidification and Minor Ce Addition

Ruan

Wang

Wei

2021

steel research int.

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“…The carbon concentration in the diffusion layer is not the same at all depths, which affects the mechanical properties of the surface (5). The ideal value of the carbon concentration in the surface layer ranges from 0.75% to 1.1%, which is a value close to the eutectoid concentration (6). The carburized layer consists of a over eutectoid zone (secondary cementite and perlite), a eutectoid and under eutectoid zone (perlite and ferrite) (7).…”

Section: Introductionmentioning

confidence: 89%

“…Chromium increases the carbon content the most. Non-carbide-forming elements (Si, Ni) reduce the carbon content and slow down the diffusion of carbon in the surface layer (9,10). Currently, modern methods of carburizing are used, which include vacuum (low pressure) carburizing with subsequent quenching into oil or quenching with gas (nitrogen, helium).…”

Section: Introductionmentioning

confidence: 99%

Change of Geometric Accuracy of Structural Steels after Carburizing in Gas

Dobrocký¹,

Pokorny²,

Joska³

et al. 2020

ECS Trans.

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Nowadays, carburizing at low pressure or vacuum carburizing is often used, which is a modification of carburizing in gas, while carburization is performed at pressures well below the level of atmospheric pressure (101 kPa). The advantage of this process is that no internal oxidation occurs; carburizing has a higher rate and uniformity of carburization, good reproducibility of the process and lower deformation. Carburizing is mainly used for parts subjected to abrasion (eg gears). However, even with this process, the geometric accuracy and surface texture of the parts change. The changes of geometric accuracy of ground samples from carbon steel C45, low-alloy Mn-Cr carburizing steel 16MnCr5 and medium-alloyed Ni-Cr carburizing steel 14NiCr14, which were vacuum-carburized in a CO/CH4 atmosphere, were evaluated in this work. Geometric accuracy was evaluated by measurement using a 3D coordinate measuring machine, surface texture using a coherent correlation interferometer. After the carburizing process, changes in the dimensions of the samples were found in all steels. For C45 steel, the sample dimensions were reduced by 0.028 mm ± 0.004 mm, the surface roughness expressed by the parameter Ra decreased by 0.28 µm, which is 20%. In case of carburizing steels there was an increase in the dimensions of the samples, especially in the case of 14NiCr14 steel and a smaller difference in surface roughness. The same parameters of the carburizing process lead to different behaviour of carburized parts in different steels, in terms of changes in dimensions and surface texture.

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“…Meanwhile, La enhances the surface bombardment effect, increasing the crystal defects such as vacancies and dislocations and further reducing the N content in the nitrided layer, which accelerates the diffusion of N atoms and produces solid solution strengthening. Thus, the thickness of compound and effective hardening layer is increased, and the nitriding process is accelerated [19,20].…”

Section: Semmentioning

confidence: 99%

Low-Temperature Plasma Nitriding of 3Cr13 Steel Accelerated by Rare-Earth Block

You

Yan

et al. 2021

Coatings

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The plasma nitriding of 3Cr13 steel occurred at 450 °C for 4, 8 and 12 h in NH3 with and without rare earth (RE). The nitrided layers were characterized using an OM, SEM, TEM, XRD, XPS, microhardness tester and electrochemical workstation. The modified layer, with and without La, are composed of a compound layer and diffusion layer from surface to core. After the addition of La during nitriding, the maximum increase of layer thickness, mass gain and average microhardness was 15.6%, 35.8% and 212.50HV0.05, respectively. With the increase of the proportion of ε-Fe2-3N, the passivation zone of the corrosion resistance curve increases from 2.436 to 3.969 V, the corrosion current density decreases, the corrosion potential and pitting potential both increase, and, consequently, the corrosion resistance is significantly improved. Most of the surface microstructures of the nitrided layer was refined by the addition of La. The presence of La reduces the N content in the modified layer, which accelerates the diffusion of N atoms and, thus, accelerates the nitriding process.

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Atomistic diffusion mechanism of rare earth carburizing/nitriding on iron-based alloy

Cited by 23 publications

References 39 publications

Structure and Property Modulations of 13Cr Stainless Steel Through Microgravity Solidification and Minor Ce Addition

Structure and Property Modulations of 13Cr Stainless Steel Through Microgravity Solidification and Minor Ce Addition

Change of Geometric Accuracy of Structural Steels after Carburizing in Gas

Low-Temperature Plasma Nitriding of 3Cr13 Steel Accelerated by Rare-Earth Block

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