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Please use this identifier to cite or link to this item: http://hdl.handle.net/1974/2572


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Keywords: Bainite
Electron Backscatter Diffraction (EBSD)
Microalloyed Steel
Brittle Toughness
Low Temperature
Conventional Bainite
Acicular Ferrite
Accerelated Cooling
Rolling Strain
Plate Steel
Thermomechanical Processing
Issue Date: 2009
Series/Report no.: Canadian theses
Abstract: Low temperature cleavage fracture behaviour was investigated using four experimental microalloyed bainitic plate steels. The four plate samples were produced by different thermomechanical processing (TMP) schedules and had yield strengths in the range 540 - 670 MPa. Microstructures were characterized by optical microscopy (OM), scanning electron microscopy (SEM) and electron back scattered diffraction (EBSD). Quantitative data was obtained for prior austenite grain (PAG) size, volume fractions of two bainite types (conventional bainite and acicular ferrite) and EBSD 15° domain size. Charpy impact tests (using two notch orientations) were carried out over a range of temperatures. Cleavage facet sizes were measured on -196°C Charpy samples. The range of TMP schedules produced variations in PAG width, type of bainite and 15° domain size. The effects of these three microstructural features on cleavage crack propagation are discussed. Results indicate that the microstructures are controlled by i) deformation below TNR and ii) accelerated cooling rate. Domain structure reflects TMP. There is no clear correlation between domain size and cleavage facet size.
Description: Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2009-07-30 19:17:01.25
URI: http://hdl.handle.net/1974/2572
Appears in Collections:Queen's Graduate Theses and Dissertations
Department of Mechanical and Materials Engineering Graduate Theses

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