Effect of thermomechanical processing on grain boundary character distribution in alpha brass

The present paper reports new experimental work to evaluate two aspects of thermomechanical treatment of alpha brass: the effect on the grain boundary population of strain annealing iterations rather than single stage treatme nts, and the accompanying effect on mechanical properties, particularly duc tility. Whereas the first stage of a two stage strain - anneaIing schedule improved ductility, during the second stage there was a further improvement which was more than expected from the rather small increase in average gra in size. The ductility enhancements were related to changes in the coincide nce site lattice (CSL) Sigma3(n) populations, manifested by a combination o f changes in the overall proportions of Sigma3 boundaries from 42 to nearly 70% and the distribution of nu/nu (m), where nu/nu (m) is a measure of the proximity to the exact CSL configuration. The data were interpreted in ter ms of the types of Sigma3 boundaries generated, and the occurrence of multi ple twinning and 'back twinning', MST/4798.