Comparative study on corrosion fatigue behaviour of high strength low alloy steel and simulated HAZ microstructures in a simulated marine atmosphere

In this study, corrosion fatigue (CF) behaviour of E690 steel and simulated heat-affected zone (HAZ) microstructures were investigated in a SO₂-polluted marine atmosphere. Results revealed that E690 steel and simulated HAZ microstructures were all susceptible to CF cracking in this environment with transgranular fracture. CF cracks were prone to initiate from prior austenite grain boundaries (PAGBs) for parent metal and coarse-grained HAZ (CGHAZ), whereas few microcracks were induced for fine-grained HAZ (FGHAZ). CGHAZ exhibits inferior CF behaviour due to coarse PAGBs and long bainitic lath, whereas FGHAZ exhibits superior CF behaviour because of fine grain size and bainitic lath.