Surface Pre-Stressing to Reduce the Incidence of Stress Corrosion Cracking and Corrosion Fatigue of Welded Joints

Author:  O'Hara, Peter
Source:  Metal Improvement Company
Doc ID:  1988033
Year of Publication:  1988
Abstract:  
Controlled surface prestressing is a technique applied to many machined or fabricated surfaces to reduce the incidence of Stress Corrosion Cracking and Corrosion Fatigue. The benefit is gained by the remaoval of any surface residual tensile stresses, which can be considerable, and substituting residual compressive stresses whose magnitude can be 80% of the materials yield strength and depth 1,2 or 3mm depending ton the parameters selected. The critical factor of any material where SCC is concerned is the threshold level of tensile stress. This can be exceeded if applied or residual tensile stresses, eccentuated by any stress intensity feature, eg weld laps or geometry, result. Not only does controlled surface prestressing remove any residual surface tensile stresses, it effectively reduces the applied load witnessed on the surface and can negate the stress intensity problem.