Hydrogen-enhanced cracking of 2205 duplex stainless steel welds

Slow-displacement rate tensile tests were carried out to investigate the effect of hydrogen embrittlement on notched tensile strength (NTS) and fracture characteristics of 2205 duplex stainless steel weld. The hydrogen embrittlement susceptibility of the specimens was correlated with microstructures of the fusion zone. The results indicated that all the specimens were susceptible to gaseous hydrogen embrittlement but to different degrees. The susceptibility decreased with increasing austenite content in the weld metal. The orientation with respect to the rolling direction had a great influence on the impact toughness of the base plate. Preheating before welding or changing the plasma-assisted gas from He to N2 could raise the γ content of the fusion zone and improve the impact toughness. In case of the post-weld heat-treated weld (PW), the presence of randomly oriented acicular and blocky γ in the fusion zone led to the highest impact energy and NTS among the specimens being tested. Scanning electron microscopy (SEM) fractographs revealed that all specimens underwent a significant change in fracture mode from ductile in air to quasi-cleavage fracture in H2.