Effect of residual stresses on ductile fracture of pipeline steels

Welding residual stress is one of the main concerns for fabrication and operation of steel structural due to its potential effect on structural integrity. This paper focuses on the influence of welding residual stress on ductile crack growth resistance of pipeline steels based on the elastic-plastic fracture mechanics theory and the constitutive models. Residual stresses were introduced into the model by using the so-called eigenstrain method. The complete Gurson model has been employed to calculate the ductile crack growth resistance based on the ABAQUS finite element software. The ductile crack growth resistance curves (CTOD-R curve) at large yielding conditions were numerically calculated and analyzed using the single edge notched bending (SENB) specimens and the single notched tension (SENT) specimens. Results show that residual stresses reduce the ductile crack growth resistance for deep-cracked specimens. However, for the shallow-cracked specimens, the effect of residual stress on ductile crack growth resistance can be ignored.