| Summary: | Student Number : 9102778K -
MSc(Eng) dissertation -
School of Chemical and Metallurgical Engineering -
Faculty of Engineering and the Built Environment === Strain ageing anisotropy, a surprising property of iron, implies that interstitials,
which are non-lattice obstacles, can give non-symmetrical opposition to glide. Al-
though this has been investigated by others, it is shown that it is di±cult to eliminate
extraneous residual stresses during testing. An Avery torsion machine was adapted
for the study of strain ageing anisotropy through the design of a torque and twist
measurement system. This required the optimization of sensitivity, stiffness and me-
chanical stability criteria, while ensuring practicality. When a ¯ne-grained sample
with circumferential groove was tested a sharp yield point and lack of yield after
ageing in the reverse direction was observed. Although more testing is required, it
con¯rms the results of other researchers. In testing it was found that the quality
of the sample machining was critical in achieving an accurate yield, and the groove
design must be reviewed and improved. While the system measured to the required
torque resolution, the strain measurement system could be improved by redesign
and better calibration statistics.
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