The effect of Si on the kinetics of Nb(C,N) precipitation was investigated by using fractional softening measurements. Compression specimens, with diameters of 7.6 mm and lengths of 11.4 mm, were prepared from four Nb microalloyed steels containing a range of Si concentrations from 0.01 wt% to 0.41 wt%. The stress relaxation method was used in the beginning of this work, but the majority of the experimental results were derived from double-hit compression tests, with a strain of 0.3 applied to represent each pass at a strain rate of 0.1/sec. A solution heat treatment was applied immediately prior to each test. / It was found that the rate of Nb(C,N) precipitation in hot deformed austenite increases with Si concentration. This phenomenon is attributed to the increases in both the Nb diffusivity and the activities of C and N that result from Si addition. Based on the Dutta and Sellars model, an expression for the effect of strain rate on the precipitation start time has been proposed. The present experimental results can then be extrapolated to mill conditions.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.31048 |
| Date | January 2000 |
| Creators | Dong, Jin Xiang, 1961- |
| Contributors | Jonas, J. J. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Engineering (Department of Mining and Metallurgical Engineering.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001809285, proquestno: MQ70226, Theses scanned by UMI/ProQuest. |
Page generated in 0.0013 seconds