Thermomechanical Manipulation of Crack-Tip Stress Field for Resistance to Stress Corrosion Crack Propagation

Abstract

Corrosion-assisted propagation of an existing crack is profoundly influenced by the stress intensity at the crack tip. This article presents the first results of thermomechanical conditioning (TMC) for local manipulation of material at and ahead of the crack tip, in an attempt to retard/ stop crack propagation. Prenotched round tensile specimens of mild steel were subjected to rotating bending to generate a fatigue precrack, and then to apply localized thermomechanical conditioning. The threshold stress intensity factor (K ISCC ) for stress corrosion cracking (SCC) of precracked specimens with and without TMC was determined in a caustic environment. Results suggest that TMC can increase K ISCC . Finite element analysis of the specimens suggests development of compressive stresses at and around the crack tip, which is expected to improve the resistance to stress corrosion crack propagation (since stress corrosion cracks can propagate only under tensile loading).