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Effect of molybdenum on phase transformation and microstructural evolution of strip cast steels containing niobium
journal contribution
posted on 2019-01-01, 00:00 authored by Lu JiangLu Jiang, Ross MarceauRoss Marceau, Thomas DorinThomas Dorin, Peter HodgsonPeter Hodgson, N StanfordMolybdenum (Mo) is known to have a complex effect on phase transformations and precipitation in steels manufactured by conventional casting. The present work aims to examine the effect of Mo on phase transformations in Nb-containing steels produced by strip casting. Advanced experimental techniques have been utilised to simulate the strip casting process, and the microstructural features of the rapid solidification are retained for further study. Two cooling conditions from the austenite phase field were examined, isothermal holding and continuous cooling. It was found that at high cooling rates, the addition of Mo delayed the nucleation of bainite and lowered the bainite start temperature, but did not alter the bainite growth rate. The addition of Mo was also found to result in a slower transformation rate of polygonal ferrite under both isothermal and continuous cooling conditions. Thermodynamic simulations indicated that Mo did not affect the growth velocity of the polygonal ferrite, and quantitative metallography showed the nucleation density was significantly reduced by Mo addition. For the slowest continuous cooling rate, the addition of Mo completely inhibited pearlite formation, with bainitic ferrite forming instead. This has been suggested to be the result of the suppression of pearlite nucleation, rather than inhibition of growth.
History
Journal
Journal of materials scienceVolume
54Issue
2Pagination
1769 - 1784Publisher
SpringerLocation
Cham, SwitzerlandPublisher DOI
ISSN
0022-2461eISSN
1573-4803Language
engPublication classification
C1 Refereed article in a scholarly journalCopyright notice
2018, Springer Science+Business Media, LLC, part of Springer NatureUsage metrics
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