Fast Fracture Toughness and Crack Arrest Toughness of Reactor Pressure Vessel Steel

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Abstract
Crack propagation and arrest measurements have been made using six pressure vessel steels and a submerged-arc weldment. The base-metal crack arrest toughness, KIm, is found to increase linearly with temperature above nil-ductility transition (NDT), and between NDT and (NDT + 100°C) is substantially greater than KIR. NDT is found to be a more consistent reference temperature than room temperature NDT (RTNDT). It is suggested that the absolute value of KIm at any temperature is composed of cleavage and dimpled-rupture contributions, with regions of dimpled rupture being contained in shear walls normal to the crack plane and parallel to the direction of crack travel. Shear walls which do not completely fracture are the source of unbroken ligaments observed on the fracture surface. The arrest toughness of the weldment is significantly lower than that of the baseplate and displays little evidence of unbroken ligaments or shear walls.