Prediction of ductile failure of high-strength pipeline steel based on SMCS model

In order to ensure the transportation safety of high-strength steel oil and gas pipeline, the design and evaluation of ductile fracture is crucially important. The stress modified critical strain (SMCS) model that considers microstructure void damage evolution and effectively combines macro finite element structure analysis is applicable for ductile failure prediction. Based on the tensile experiment data of X80 pipeline steel notch specimen, its ductile cracking is simulated by finite element with Gurson damage model. The results show that ductile cracking appears at the center of the specimen, the major contribution of void volume ratio increase is from void expansion and void nucleation has low impact on ductile cracking, which verifies the related hypothesis of SMCS model. Accordingly, the ductile failure index and the failure criterion of this pipe steel are obtained. The failure criterion is formally simple and convenient for engineering application.