Carbon Diffusivity in Iron-Chromium Alloys

Blazek, K. E.; Cost, J.R.

doi:10.2320/matertrans1960.17.630

Cited by 17 publications

(9 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Therefore thermal segregation calculations using a simple McLean type model are approximately consistent with observed grain boundary solute enrichments in the irradiated condition; indeed, in the case of P the simple models predict even higher concentrations than observed in this study [44]. However, thermal segregation depends on kinetics, as well as thermodynamics, hence on the entire alloy time-temperature history and solute diffusion properties [44][45][46]; and only interstitial C is expected to be fully equilibrated. Further, thermal non-equilibrium segregation (TNES), due to flow of excess quenched-in vacancies to boundaries, may also occur [47] along with other complications not treated in simple pure binary alloy Langmuir-McLean type models [43].…”

Section: Discussionsupporting

confidence: 82%

Microstructural changes in a neutron-irradiated Fe–6 at.%Cr alloy

Bachhav

Yao

Odette

et al. 2014

Journal of Nuclear Materials

View full text Add to dashboard Cite

The microstructural and chemical changes in a Fe-6 at.% Cr binary model alloy neutron irradiated to 1.82 dpa at 290 o C were investigated using atom probe tomography. After irradiation, Si and Cr are found segregated to dislocation loops, which were analyzed in terms of number density, size, and habit plane. Grain boundary chemistry was quantitatively compared between the as-received and the neutron irradiated alloys. The results are discussed in the context of equilibrium segregation, radiation-enhanced diffusion, and/or radiation induced segregation.

show abstract

Section: Discussionsupporting

confidence: 82%

Microstructural changes in a neutron-irradiated Fe–6 at.%Cr alloy

Bachhav

Yao

Odette

et al. 2014

Journal of Nuclear Materials

View full text Add to dashboard Cite

show abstract

“…[9,13,14] Nevertheless, the presence of these alloying elements in steel impedes the carburizing process. [13] In comparison, Cr and Mo decrease the carbon diffusivity in austenite, [4,15] though these elements accelerate the overall carburizing performance of steel. [13] These phenomena become more convoluted as the composition of alloy steels grows increasingly complex.…”

Section: Introductionmentioning

confidence: 99%

Effect of Alloy Composition on Carburizing Performance of Steel

Rowan

Sisson

2009

J. Phase Equilib. Diffus.

View full text Add to dashboard Cite

This paper investigates the effect of alloy composition on the gas carburizing performance of AISI 1018, 4820, 5120, and 8620 steels. The mass-transfer coefficients and carbon diffusivities were calculated from experimental measurements using direct flux integration. Although steels with high concentration of austenite-stabilizing elements (Si, Ni) increased carbon diffusivity in austenite, they significantly reduced the kinetics of carbon transfer from the atmosphere to the steel surface and resulted in lower weight gain. Despite lowering the carbon diffusivities, steels alloyed with carbide-forming elements (Cr, Mo) significantly increased the mass-transfer coefficient in the atmosphere and enhanced the rate of carbon profile evolution. The experimentally determined carbon diffusivities were in good agreement with the carbon diffusivities obtained from the thermodynamic and kinetic databases in DICTRA. Overall, using the concentration dependent mass-transfer coefficient and carbon diffusivity in various alloy steels helped explain the experimentally observed variations in the carbon concentration profiles and the effective case depths. Recommendations are made to help achieve better case depth uniformity within a carburizing workload.

show abstract

“…Measurements of carbon diffusivity using diffusionannealed couples were studied by various researchers. [1][2][3]13,14] In their analyses, the coefficients of carbon diffusion were calculated from the concentration profiles using the Boltzmann-Matano method. [15] The driving force for diffusion is the concentration gradient between the components of the diffusion couples and/or the differences in carbon activities due to the effect of alloying.…”

Section: Available Methods For Measuring Carbon Diffusivitymentioning

confidence: 99%

“…Often, the coefficient of carbon diffusion is determined from a model of a solid-solid diffusion couple. [1][2][3] The application of such models to carburizing invariantly introduces a certain level of approximation and uncertainty due to a rough, though convenient, assumption of constant surface concentration at the interface with time. More accurate modeling of the gascarburizing process must account for mass transfer from the carburizing gas atmosphere to the steel surface, the surface reaction, and further carbon diffusion into the steel.…”

Section: Introductionmentioning

confidence: 99%

Carbon Diffusion in Steels: A Numerical Analysis Based on Direct Integration of the Flux

Karabelchtchikova¹,

Sisson²

2006

Journal of Phase Equilibria & Diffusion

View full text Add to dashboard Cite

In the early 1970s, Professor Dayananda developed a technique for the direct integration of fluxes from the concentration profiles in vapor-solid diffusion couples to determine diffusion coefficients and atomic mobilities. As part of a project to control and optimize the industrial carburization process in mild-and low-alloyed steels, a modified integration analysis was applied to determine the mass transfer coefficient in the gas boundary layer and carbon diffusivity in austenite. Because carbon flux and surface carbon content vary with time during single-stage carburizing even with a fixed carbon potential in the atmosphere, a mass balance at the gas-solid interface must serve as a boundary condition. This article discusses the numerical modeling of gas carburizing, and focuses on calculating the mass transfer and carbon diffusivity parameters using the simulated concentration profiles. This approach validates the proposed method by comparing the calculated parameters with those used in simulation. The results were compared with previous determinations and predictions reported in the literature.

show abstract

Carbon Diffusivity in Iron-Chromium Alloys

Cited by 17 publications

References 9 publications

Microstructural changes in a neutron-irradiated Fe–6 at.%Cr alloy

Microstructural changes in a neutron-irradiated Fe–6 at.%Cr alloy

Effect of Alloy Composition on Carburizing Performance of Steel

Carbon Diffusion in Steels: A Numerical Analysis Based on Direct Integration of the Flux

Contact Info

Product

Resources

About