Hydrogen Embrittlement at the Interface of Clad Steel Pipes – Fracture Mechanical Testing and FE Simulations

The presence of a Ni-interlayer between clad and pipeline steel was found to reduced the fracture initiation toughness with 44 % for testing in air, while it raised the fracture initiation toughness with 216 % for testing under CP. • Fracture mechanical testing of the weld heat-affected zone clad interface is currently being conducted in air and under CP. • A coupled mass diffusion and cohesive analysis framework has been developed for numerically assessing the effect of hydrogen on the fracture toughness. Initial results were presented and compared with experiments. • Nanomechanical testing is being considered as an option for establishing the mechanical properties at the bi-metallic interface, for input to the numerical model. • A procedure for importing hydrogen concentration fields and residual stresses from WeldsimS into Abaqus as initial boundary conditions has been developed, and will be applied in cohesive zone modelling of hydrogen induced fracture of repair welded clad pipes.