Browsing by Author "Wittridge, N"

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    A microtexture based analysis of the surface roughening behaviour of an aluminium alloy during tensile deformation.
    (Elsevier, 1999) Wittridge, N; Knutsen, R
    The development of surface roughening during uniaxial tensile deformation, with particular attention to the development of parallel ridges and valleys (ribbed profile), has been investigated for a commercial aluminium alloy. A comparison has been made between two samples which exhibit different propensities for roughening and a detailed microstructural characterisation of these samples has been performed in order to explain the differences. Microstructural characterisation techniques included polarised light microscopy, bulk texture and microtexture. In addition, yield properties were calculated from the microtexture data using polycrystal plasticity analysis. The results show that the differences in the roughening behaviour can be attributed to spatial differences in texture at the specimen surface whereby R-component colonies in a cube matrix produce differential straining, which eventually leads to strain localisation through the specimen thickness to produce a ribbed profile.
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    Recovery and recrystallization characterization in ferritic stainless steel by using electron channeling contrast.
    (Elsevier, 1996) Wittridge, N; Knutsen, R
    Electron channeling contrast (ECC) imaging in the scanning electron microscope (SEM) provides a useful method of characterizing the microstructural evolution of wrought ferritic stainless steel. The ability to examine bulk specimens in the SEM without involving the tedious etching procedures normally associated with light microscopy is demonstrated. Recovered and recrystallized domains are clearly distinguished by ECC, and the sensitive relationship between grain orientation and grey-level contrast gives rise to a clear delineation of the overall recrystallized grain structure. Artifacts sometimes introduced by the examination of etched microstructures are avoided, and the continuous assessment of the microstructure in the through-thickness direction is easily accomplished in a single sample.