Stress corrosion crack initiation in α-brass exposed to sodium nitrite solutions

Abstract

The initiation of cracks in α-brass exposed to sodium nitrite solutions occurred most readily at grain and twin boundaries, despite the crack propagation being predominantly transgranular. Only when the slip step height exceeded the film thickness was transgranular initiation observed, although that was after prior intergranular initiation. Intergranular crack initiation was also observed in other systems that display transgranular propagation, involving α-brass in formate and ammoniacal solutions and copper in sodium nitrite. It is suggested that the preference for intergranular initiation is primarily due to differences in the mechanical properties of the film where it overlies boundaries.