Ductile Fracture Prediction of X80 Pipeline Steel Using Void Growth Model

Abstract

In this study, the Void Growth Model (VGM) is employed to predict the ductile fracture of X80 pipeline steel. The X80 pipeline tends to be applied in challenging scenarios, such as extremely deep water and long-distance pipelines, which might cause a ductile fracture; however, the study of ductile fractures for pipeline steel is rare, especially for X80 pipeline steel. To understand ductile fractures of X80 pipeline steel, a hybrid numerical–experimental calibration method is used to determine the fracture parameter for the VGM model. The toughness capacity defined by the critical void growth index (VGI) in this study is determined to be 4.304. A shear-tension specimen is applied to verify the calibrated VGM. The results show that the calibrated VGM can predict the fracture initiation of the shear-tension specimen. In addition, the fracture of the shear-tension specimen initiates at the center of the section and propagates to the edge of the groove of the specimen. The initiation of fracture is identical to the testing observation.