A Study on the Stress Corrosion Cracking Susceptibility of α-Brass in Ammonical Environment

Abstract

For the purpose of investigating the effects of annealing, deformation and additional elements on the susceptibility of stress corrosion cracking of α-brass in ammonical environment, stress corrosion tests were carried out by bending or elongating by a lever-system type apparatus and an Instron type tensile-testing-machine. Commercial high-purity 70:30 brass with or without additional elements, such as Be,Y,Si and Mischmetall, were stress corroded. During the tests, the measurements of electric resistance and stress relaxation were carried out to trace the crack initiation and propagation.
It has been found that the time to failure, its stress dependence and the modes of cracks are very sensitive to deformation and annealing before tests. The alloys containing 0.1 at% Misch-metall or 1.0 at%Si have good resistance against stress corrosive conditions. Additional elements have effects mainly on the crack propagation. The fact that pre-strained specimens are much susceptible to trans-granular cracking may correspond to the dislocation distributions.