| Autor: |
Hiroyuki Takamiya, Kouji Tanaka, Hideaki Ikehata, Hiroyuki Mizuno |
| Rok vydání: |
2011 |
| Předmět: |
|
| Zdroj: |
Solid State Phenomena. :1177-1182 |
| ISSN: |
1662-9779 |
| DOI: |
10.4028/www.scientific.net/ssp.172-174.1177 |
| Popis: |
In order to predict microstructures during vacuum carburizing, the model which simulates not only the carbon(C) diffusion but also growth/dissolution of cementite(θ) is required. For development of a new model we applied vacuum carburizing to low alloy steels and analyzed the distribution of C and θ by GD-OES and image analysis of microstructures. The C in retained austenite(γ) phase after carburizing was also measured by lattice constants obtained from XRD. We also simulated multi-component diffusion with γ matrix and θ layer to analyze a velocity of the moving interface. The new carburizing model was proposed based on the findings, which suggest that C in γ phase at the carburizing surface is supersaturated and corresponds to C concentration for metastable equilibrium condition to graphite. The growth and dissolution of the θ follow a square root of time with the coefficients controlled by diffusion of Si in γ and Cr in θ respectively. The required parameters such as diffusivity coefficients are obtained by the CALPHAD method. The calculated C distributions and volume fractions of θ represent the experimental results. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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