Effects of scratching on corrosion and stress corrosion cracking of Alloy 690TT at 58 °C and 330 °C

Scratched Alloy 690TT were characterized using X-ray stress analysis technique, nano-indentation, SEM, electrochemical and immersion tests. The stresses adjacent to the scratches, which resulted from scratching, were tensile parallel to the scratches and compressive perpendicular to the scratches. In the acidic sodium chloride solution at 58 degrees C, scratching caused E-corr to shift negatively owing to a transient anodic current accompanied by a larger difference between E-corr and the potential of zero charge. Pit 330 degrees C in the lead-containing caustic solutions, SCC initiated at the scratch-banks and scratch-beds after 30 days' immersion. Scratched Alloy 69017 exhibited both IGSCC and TGSCC in initiation. (C) 2009 Elsevier Ltd. All rights reserved.