Effect of Notch Orientation on Fracture Toughness of a Submerged Arc Weld

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Abstract This paper reports the effect of notch orientation on the fracture toughness of a submerged arc weld as determined by performing standard fracture mechanics tests using single edge notched bend specimens having through-thickness and surface notches. The notch orientations used were NP (through-thickness notch at weld centerline running parallel to the weld direction), NQ (surface notch at weld centerline with the notch plane parallel to the weld but running perpendicular to the weld direction from the cap toward the root), and PQ (a surface notch where the notch plane is transverse to the weld and propagating from the cap toward the root). Testing was carried out over a range of temperatures. It was found that the NP notch orientation led to less scatter in fracture toughness, and the greatest amount of scatter was shown for NQ and PQ notch orientations. The test data for each notch orientation were used to determine the reference temperature T0 using ASTM E1921-13 and FITNET procedures. Values of T0 were subsequently used to define the temperature-versus-toughness transition curve (master curve) for each notch orientation. The fracture toughness predicted by the master curve analyses showed differences among the three notch orientations. As the FITNET procedure is more conservative for highly scattered data than the ASTM procedure, the predicted fracture toughness for the PQ and NQ notch orientations was significantly less than that for the NP notch orientation.