Abstract This paper presents a phenomenological model of ductile fracture for the API X65 steel using the Gurson–Tvergaard–Needleman (GTN) model. Experimental tests and FE damage simulations using the GTN model are performed for smooth and notched tensile bars, from which the parameters in the GTN model are calibrated. Comparison of experimental data of pre-strained, notched tensile and fracture toughness tests with finite element (FE) damage analyses show good agreements, suggesting the validity of the calibrated parameters. As application, the developed GTN model is applied to predict the pre-strain effect on deformation and fracture and the results are compared with experimental data.