Interactions between diffusing impurity atoms and dislocations can occur during or following the deformation of metals. These interactions cause dislocation pinning, leading to strain aging. At lower temperatures (<400°C), the relevant solutes are interstitial (in particular, carbon and nitrogen). At higher temperatures (>800°C), substitutional impurities are expected to be most influential. The same mechanisms that result in the yield drops, increased flow stresses and increased work hardening associated with strain aging at low temperatures should result in significant modification of recovery and recrystallization behaviour at higher temperatures. / The present work involves the deformation of austenitic (304) stainless steel at high temperatures (800°C to 1280°C) in 1-hit and 2-hit high-temperature compression and multi-hit hot torsion testing. Experimental variables include the strain rate, temperature and interpass time. / Significant anomalies in the static softening kinetics are observed; under certain deformation conditions, the normal relationship between temperature and fractional softening is reversed. This effect is attributed to the non-equilibrium segregation of phosphorus during the interpass holding time. Analysis of dynamic recrystallization (DRX) in the material has revealed retardation of the initiation of recrystallization; this effect is explained in terms of the segregation of substitutional elements to the boundaries of new DRX grains.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.84847 |
| Date | January 2004 |
| Creators | Stewart, Gregg Ryan |
| Contributors | Jonas, John 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 | Doctor of Philosophy (Department of Mining, Metals and Materials Engineering.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 002150232, proquestno: AAINQ98378, Theses scanned by UMI/ProQuest. |
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