USING HUGE PENDULUM IMPACT TESTER TO EVALUATE THE DYNAMIC FRACTURE TOUGHNESS AND CRACK BEHAVIOR OF PIPELINE STEELS

摘要

A 40kJ instrumented pendulum machine has been used to perform DWTT test for an API X80 pipeline steel to acquire the force-displacement curve, which divides the total DWTT energy into crack initiation and propagation subdivisions. A parameter of crack propagation energy density is proposed to characterize the ductile fracture toughness, independent of thickness, notch shape. Moreover, Key Curve method is employed to establish the relationship between crack extension and tup displacement, which provides a way to investigate the crack behavior and DWTT energy distribution from fracture surface. Then CTOAc, as a measure of material resistance to ductile fracture, could be reliably estimated by the accurate determination of crack propagation energy, exclusive of non-steady state stage and shear lips.