Numerical and Experimental Study on Critical Crack Tip Opening Dis-placement of X80 Pipeline Steel
High strength pipelines is widely used in the long distance transportation of oil and gas resources. Fracture toughness is one significant material property for these high strength pipeline steels. In this study, the critical crack tip opening displacement (CTOD) of X80 pipeline steel was studied both experimentally and numerically. 3 point bending tests were conducted for 6 specimens with 2 thicknesses. Numerical model using the extended finite element method was also established, with maximum principle strain criterion used for damage initiation. Results show that, the critical CTOD decreases with the increases of the specimen thickness, and to give reasonable simulation results, larger maximum principle strain criterion should be used in the numerical model. This study can be referenced for the performance evaluation and quality assurance for X80 steel gas pipelines.