Susceptibility to hydrogen-induced cracking in H₂S corrosion environment of API 5L-X80 welding metal

Abstract

The susceptibility to hydrogen-induced cracking in hydrogen sulphide (H 2 S) environment of welded API X80 steel was studied. The flux-cored arc welding process was employed with E71-T1 and E71-T8K6 wires. The welding parameters were kept constant, but the samples were welded using different preheat temperatures (room temperature and 1008C). The gapped bead-on-plate (G-BOP) test was used. The specimens of modified G-BOP tests were exposed to an environment saturated with H 2 S, as recommended by the NACE TM0284 standard. The weld beads were characterized by optical microscopy and the level of residual hydrogen in the samples was measured. The fracture surface areas of hydrogen-induced cracking were calculated and the fracture mode was discussed. It was found that the preheating temperature of 1008C was enough to avoid cracking, even in the presence of H 2 S. It was also found that the E71-T8K6 wire was more susceptible to cracking, and the typical mixed-mode fracture was predominant in all samples.