Abstract
Two different preheating treatments were used to vary the Al6 Mn dispersoid characteristics in AA 5182. High temperature followed by slow cooling produced coarse, needlelike dispersoids which allowed rapid recrystallisation following hot rolling, whereas a low temperature preheat produced afine dispersion of low aspect ratio particles which retarded recrystallisation. Long, unrecrystallised bands persisted in the hot rolled material subected to the low temperature preheat even after holding for 24 h at the final pass temperature. Micro-orientation determinations within the bands showed that they were predominantly of the brass (Bs) orientation, {110}〈112〉, confirming the results of X-ray bulk texture analyses. The results are considered conclusive evidence of the widely reported higher resistance to recrystallisation of the Bs orientation compared with other orientations in rolled high stacking fault energy fcc metals. The Bs oriented bands could be removed by annealing at a temperature substantially greater than that experienced in the final hot rolling pass.
MST/1475
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