Effect of bending load on the creep failure behaviour of a pressurised thick walled CrMoV pipe weldment

摘要

This paper describes the results of a finite element investigation into the effects of bending on the creep failure behaviour of an internally pressurised thick walled pipe weld. The material properties used were those for a service-exposed 1/2Cr1/2Mo1/4V:2 1/4Cr1Mo weldment at 640 deg C. The peak rupture stresses in each material zone, which were obtained from steady-state analyses, were used to predict failure lives for a range of bending load levels. The rupture stresses showed very little variation across the heat-affected zone, in the dominant stress regions, for low and moderate bending loads. However, the variation is more significant when the bending load is high but still within the allowable limits of design codes. The results obtained indicate that, in addition to the pressure, there is a higher probability of type IV cracking occurring, when an external (system) bending load is present. The results obtained were compared with those obtained for the uniform end load cases.