Cause and Applicability Analysis on Abnormal Fracture of DWTT Sample of X80M High Strength and Toughness Thick Wall Pipeline Steel

The fracture process, absorbed energy and fracture morphology of the sample of X80M high strength and toughness thick wall pipeline steel in drop weight tear test (DWTT) were studied by the method of using pendulum and drop hammer with high-speed camera, and the fracture of DWTT sample was compared with that of the real steel tube. The results show that for X80M high strength and toughness thick wall pipeline steel, no matter the fracture was hammered by pendulum or drop hammer, the probability of abnormal fracture was equal at 0 ℃; the reason of abnormal fracture was that the impact of heavy hammer caused obvious compression plastic deformation and deformation hardening of high strength and toughness thick wall pipeline steel; the abnormal fracture couldn't really characterize the material properties, and DWTT was not suitable for the evaluation of brittle fracture resistance of high strength and toughness thick wall pipeline steel.