Environmental strength evaluation of welded steel joint in seawater

Effect of applied potential on fatigue crack propagation behavior of API X80 steel in seawater

“…It has also been reported that the environmental effect on FCP in low K regime is negligible as crack extension is dependent on achieving a critical level of crack tip cyclic strain that is independent of environmental condition [22,40,41]. Similarly, mechanical effects dominate and the crack is believed to advance as a faster rate than the diffusion of hydrogen in steel at high values of K [22,36,41]. In intermediate K regime, the increase in FCP rates for steels in seawater under CP potentials has been reported compared to an air environment, due to the effect of hydrogen within and immediately ahead of the crack tip plastic zone [22,42,43].…”

“…The pipelines and offshore structures are protected against external corrosion by means of protective coatings and CP [9][10][11]. Polarization at potentials in the range of -800 to -1,100 mV SCE is generally imposed, but very negative levels can be reached on overprotected areas close to the impressed current anodes [36,37]. The enhanced entry and transport of hydrogen produced by the over-imposed CP potential could therefore increase the FCP rates along with the loss of ductility [12].…”