The role of local strains from prior cold work on stress corrosion cracking of α-brass in Mattsson's solution

• Published in: Materials characterization Vol. 92; pp. 127 - 137
• Main Authors: Ulaganathan, Jaganathan, Newman, Roger C.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.06.2014; Elsevier
• Subjects: Applied sciences; BACKSCATTERING; Boundaries; BRASS; BRASSES; Cold work; COLD WORKING; Corrosion; Corrosion environments; CRACK GROWTH; CRACK PROPAGATION; CRACKING; CRACKS; Cross-disciplinary physics: materials science; rheology; DISLOCATIONS; DISSOLUTION; Electron backscatter diffraction; ELECTRON DIFFRACTION; ELECTRONS; Exact sciences and technology; GRAIN BOUNDARIES; MATERIALS SCIENCE; Metals. Metallurgy; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Solidification; STRAIN; Strain localization; STRAIN RATE; STRAINS; STRESS; STRESS CORROSION; Stress corrosion cracking; Strain localization; Stress corrosion cracking; Electron backscatter diffraction; Cold work; Work hardening; Corrosion; Electron diffraction; Cold cracking; Brass; Surface treatments; Copper base alloys
• ISSN: 1044-5803; 1873-4189
• DOI: 10.1016/j.matchar.2014.03.005

The dynamic strain rate ahead of a crack tip formed during stress corrosion cracking (SCC) under a static load is assumed to arise from the crack propagation. The strain surrounding the crack tip would be redistributed as the crack grows, thereby having the effect of dynamic strain. Recently, several studies have shown cold work to cause accelerated crack growth rates during SCC, and the slip-dissolution mechanism has been widely applied to account for this via a supposedly increased crack-tip strain rate in cold worked material. While these interpretations consider cold work as a homogeneous effect, dislocations are generated inhomogeneously within the microstructure during cold work. The presence of grain boundaries results in dislocation pile-ups that cause local strain concentrations. The local strains generated from cold working α-brass by tensile elongation were characterized using electron backscatter diffraction (EBSD). The role of these local strains in SCC was studied by measuring the strain distributions from the same regions of the sample before cold work, after cold work, and after SCC. Though, the cracks did not always initiate or propagate along boundaries with pre-existing local strains from the applied cold work, the local strains surrounding the cracked boundaries had contributions from both the crack propagation and the prior cold work. •Plastic strain localization has a complex relationship with SCC susceptibility.•Surface relief created by cold work creates its own granular strain localization.•Cold work promotes crack growth but several other factors are involved.