Critical Driving Forces for Formation of Bainite
Autor: | Mats Hillert, Lars Höglund, Peter Kolmskog, Lindsay Leach, Annika Borgenstam |
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Rok vydání: | 2018 |
Předmět: |
010302 applied physics
Empirical equations Imagination Structural material Materials science Bainite media_common.quotation_subject Metallurgy Metals and Alloys Thermodynamics 02 engineering and technology 021001 nanoscience & nanotechnology Condensed Matter Physics Alloy composition 01 natural sciences Mechanics of Materials Ferrite (iron) 0103 physical sciences Metallic materials 0210 nano-technology Ternary operation media_common |
Zdroj: | Metallurgical and Materials Transactions A. 49:4509-4520 |
ISSN: | 1543-1940 1073-5623 |
Popis: | An empirical equation for predicting bainite start temperatures of steels was recently derived by starting from binary Fe-C alloys and continuing with ternary Fe-C-M alloys. This result is now illustrated with a family of B S lines in a T,C diagram for a series of constant Mn contents. The critical driving force for the formation of ferrite is calculated for diffusionless or diffusional processes, and these quantities are used as dependent variables with carbon content or temperature as independent variables. Negative critical driving forces are predicted for a diffusionless process in binary Fe-C alloys, showing that this process cannot apply to the formation of bainite. The critical driving force for a diffusional process increases strongly with decreasing temperature and increasing carbon content. Mn and Ni, contrary to Cr, Mo and Si, have remarkably small effects on this critical driving force. The results are discussed by imagining that the magnitude of the critical driving force is governed by the height of an energy barrier that must be surmounted during growth. It is modeled as completely determined by the alloy composition. It is represented with an equation evaluated by fitting to the recent empirical equation and describing the carbon dependence of the barrier. |
Databáze: | OpenAIRE |
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