Stress-corrosion cracking

We review stress-corrosion cracking (SCC) with an emphasis on recent developments in this field regarding the transgranular form of cracking. Evidence is presented indicating that transgranular SCC occurs via a series of discontinuous microcleavage events. Each event is typically 1 μm in extent and is triggered by a thin film of several hundred nm in thickness which has formed around the crack tip owing to an anodic process. This mechanism of SCC is called film-induced cleavage and we discuss its operation for many metals including stainless steels, Cu-Al alloys, α-brasses, and pure copper. Analytical calculations are presented which support the concept of film-induced cleavage. The compositional dependence of SCC in Cu-Al and Cu-Zn alloys is shown to correlate exactly with the compositional dependence of de-alloying the less noble metal element from these alloy systems. The selective dissolution process is discussed within the general framework of percolation theory.