The method for the estimation of fracture toughness of thin-walled metallic tube considering the effect of crack orientation

Abstract

Thin-walled metallic tubes are very susceptible to axial or circumferential cracks in harsh environments such as high temperature, high pressure, and severe corrosion, which seriously endangers the service safety of thin-walled tubes. Fracture toughness is an essential mechanical property index for evaluating the service safety of thin-walled metallic tubes, and its special thin-walled structure cannot be tested by using the specimens with standard configuration. In this work, based on the principle of energy density equivalence, the load–displacement and J-integral expressions of thin-walled metallic tubes with axial and circumferential cracks are proposed, and the fracture toughness test method of thin-walled metallic tubes with axial and circumferential cracks is established. Typical zircaloy cladding tubes were selected to complete the fracture test, and the influence of crack orientation on their fracture properties was investigated. The results show that the fracture toughness of circumferential cracks is lower than that of axial cracks, the circumferential cracks also face the risk of fracture failure, and the estimation of fracture properties of the cladding tubes with circumferential cracks cannot be simply replaced by axial cracks.