Five slightly different IF 409 ferritic stainless steels were investigated by means of continuous cooling compression (CCC) testing. These compression test were performed at a constant strain rate of $1.8 times10 rm sp{-4}s sp{-1}$ over a 600$ sp circ$C temperature range (i.c. from 1200$ sp circ$C- 600$ sp circ$C) at four different cooling rates (0.25, 0.5. 1.0 and 2.0$ sp circ$C/sec). The reheating temperature and time were varied and the effect of this on precipitation is discussed. / The analysis of the CCC test results, and the optical microscopy observations, indicated that neither solute drag nor phase transformation is responsible for the deviations observed in these flow curves. TEM bright field images were used to verify the presence of precipitates, and to calculate the strengthening influence of these particles on the flow curve. It is shown that, in the niobium bearing materials, the precipitation of carbonitrides is responsible for the increase in flow stress. Conversely, in the titanium bearing materials, the titanium carbonitride precipitates were determined to have no effect on the flow stress. / It was discovered that increasing the solution temperature and time resulted in the occurrence of precipitation at higher temperatures, and that these precipitates were coarsened to a greater extent. Also, when the holding temperature and/or the holding time was decreased, the amount of niobium put into solution decreased, which led to precipitation starting at lower temperatures. / A method was developed for determining the precipitation start and finish temperatures from the CCC results. These temperatures were converted to precipitation start and finish times for each of the four cooling rates. This revealed that the precipitation start and finish times increase with decreasing cooling rate in both the 0.2% Nb and 0.1% Nb + 0.1% Ti stainless steels. Finally, a continuous cooling precipitation diagram was constructed for the two niobium bearing materials using these start and finish times.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.22665 |
| Date | January 1994 |
| Creators | Moses, Robert |
| Contributors | Jonas, John J. (advisor), Yue, Steve (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: 001445163, proquestno: MM05464, Theses scanned by UMI/ProQuest. |
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