Hydrogen-induced cracking of welded X80 steel studies by experimental testing and molecular dynamics modeling

Abstract

Impact and slow strain rate tensile tests, as well as molecular dynamics modeling, were used to study hydrogen-induced cracking (HIC) of a welded X80 pipeline steel. There is the highest HIC susceptibility at the coarse-grained heat-affected zone, showing an obvious intergranular brittle fracture upon hydrogen-charging. Hydrogen atoms delay dislocation emissions, and the accumulated energy is released mainly through crack initiation. The hydrogen atoms decrease the elasticity of grain boundaries. The locations to initiate cracks in the polycrystalline system are not necessarily the sites with the highest hydrogen atom concentration, but are always at the multi-node grain boundaries.