DWTT notch characterization and analysis of X100 steel pipes

The drop weight tear test (DWTT) notch shape is a critical character to identify if any fracture exists in oil and gas pipe steels. To control the fractures and ensure the operation safety of X100 steel pipes, it is essential to determine the effects of stress state, operating temperature and material texture on DWTT notch shape of X100 steel pipes and confirm the relationship between such notch shape and fracture behavior. This paper, through a DWTT, compares the notch shapes of X100 steel pipe base material and X100 weld under a series of temperatures, considering two notch types (herringbone notch and pressed V-notch), and discusses the effects of notch type, material and temperature on DWTT notch shape. The results show that, in contrast to pressed V-notch specimen, the herringbone notch specimen presents more fracture cleavages and notch separations, and less reverse cleavage fractures, ductile fractures and shear lips. Moreover, the notch specimen has more fracture cleavages and less ductile fractures and shear lips at low temperature than that at ambient temperature. As the test temperature decreases, the length of notch separation and area of reverse cleavage fracture increase and then decrease. Additionally, the base material shows less fracture cleavages and reverse cleavages and more ductile fractures and shear lips than the weld; notch separation occurs in the base material.