Effect of Corrosion Pit Growth on the Ultimate Strength of Weld Joints

Pitting corrosion is a phenomenon that can cause alloy degradation and is potentially a critical consideration when evaluating the overall strength of welds between plates in steel infrastructure. While the literature on pitting corrosion is extensive, its application to welded joints and immediately adjacent areas is poorly understood, particularly for its effect on the degradation of ultimate joint strength. This paper presents an approach to estimating such degradation more accurately by finite element analysis of a ship ballast tank, with weld zones modelled in greater detail with the input of pitting corrosion effects. A study consisting of five (5) different corrosion models were used, with each having a corrosion pit located around the weld joint; two (2) in the weld zone (WZ), one (1) in the heat-affected zone (HAZ) and two (2) in the parent metal (PM). These analyses’ results are presented and extrapolated to determine the correlation between ultimate strength degradation with pit growth and ultimately, with time.