Assessment of residual stress, hardness, and defect tolerance in a tee joint, as-welded and after post-weld heat treatment

Abstract

The risk of hydrogen-assisted cold cracking (HACC) is often conflated with the risk of brittle fracture. However, if delayed non-destructive testing (NDT) shows there are no defects, or defects below the critical crack size, then brittle fracture is not possible. Post-weld heat treatment (PWHT) is known to reduce the risk of HACC but is not always possible to perform. To assess the effects of PWHT, the residual stresses and hardness values were measured before and after PWHT to assess the effects of PWHT on HACC susceptibility and on the critical defect sizes. The residual stresses were lower than code-based estimates. PWHT reduced the residual stress and hardness, and increased the critical crack size. Copyright Scientific Surveys Ltd