L51487 Predict the Interaction of Fracture Toughness and Constraint Effects for Surface Cracked Pipe

This report summarizes a program designed to quantify the disagreement between the standard t x 2t bend specimen and surface-cracked pipe data. The effect of untracked ligament length on upper-shelf toughness was also investigated. Ultimately, the findings will have application to pipeline girth welds. But in this first step, unwelded line-pipe steel specimens were used throughout this investigation. Obviously, weld metal specimen data would be more directly applicable to welded pipe. However, weld metal test data exhibit more scatter than base metal data (largely due to material non-homogeneity). This scatter could cloud the general data trends under investigation. Consequently, base metal specimens were used to more clearly establish these trends. This will form a basis for further investigations on weld metals.