Effect of Initial Microstructure on the Activation Energy of Second Stage During Austempering of Ductile Iron

The empirical activation energy for the reaction ( gamma )+( alpha )- > alpha +carbides on a Ni-Mo alloyed ductile iron was experimentally determined. When the iron was austempered at 573 and 593K, an activation energy of 279.9 kJ/mol was calculated; for the irons treated at 643 or 673K a value o...

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Bibliographic Details
Published in:Scripta materialia 1998-03, Vol.38 (8), p.1281-1287
Main Authors: Campos-Cambranis, R.E, Narváez Hernández, L, Cisneros-Guerrero, M.M, Pérez-López, M.J
Format: Article
Language:English
Subjects:
Applied sciences
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Materials science
Metals. Metallurgy
Physics
Treatment of materials and its effects on microstructure and properties
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Summary:The empirical activation energy for the reaction ( gamma )+( alpha )- > alpha +carbides on a Ni-Mo alloyed ductile iron was experimentally determined. When the iron was austempered at 573 and 593K, an activation energy of 279.9 kJ/mol was calculated; for the irons treated at 643 or 673K a value of 193.9 kJ/mol was determined. The initial ausferrite structure has a significant influence on the activation energy of stage II. Low temperature ausferrite requires activation energies higher than those required by high temperature ausferrite. Non-isothermal dilatometry resulted a successful technique in determining the activation energy of stage II of the austempering treatment of ductile iron.
ISSN:1359-6462
1872-8456
DOI:10.1016/S1359-6462(98)00036-0