TWI Industrial Member Report Summary 526/1995
P Woollin and P J Tubby
Environmental cracking in welded structures is often associated with the weldments as a consequence of the associated stress concentration, residual stress and crack sensitive microstructures, e.g. HAZs. Also fatigue crack initiation and early growth at welds is most likely to occur in these HAZ structures, which may have high hardness and enhanced sensitivity to hydrogen. Previous work has shown that the corrosion fatigue cracking of cathodically protected steels in seawater gives higher crack propagation rates than in air. This is believed to be due to hydrogen generation and diffusion pick-up to the crack-tip. The project has examined the fatigue of C-Mn steel heat treated to simulate HAZ structures. Threshold tests were performed in air and corrosion fatigue tests were undertaken in artificial seawater with cathodic protection applied.
- Derivation of a general approach to predicting the life of welded joints subject to environmentally assisted cracking.