Stress corrosion cracking of copper-manganese alloys-effect of some chemical variables

OCCURRENCE of stress corrosion cracking in binary copper-manganese alloys in the presence of ammonia has been first reported by Lahiri1 where it has also been observed that Mattsson's solution2 comprising CuSO4, 5H2O and (NH4)2SO4 and ammonia, a very aggressive medium for stress corrosion
cracking of brass, is very much effective in producing
ready cracking in copper-manganese alloys. Coppermanganese
system provides a wide range of solid solution; in this respect it is comparable to the copperzinc system, the stress corrosion studies of which have been carried out extensively. A few recent papers3'4'5 deal with the elect-rochemical aspects of stress corrosion cracking of alpha brass in Mattsson's solution. In this context it will be of interest to study the behaviour of homogeneous copper-manganese alloys under the variable conditions of Matt-sson's solution to get an insight into the mechanism of stress corrosion cracking.