[en] This paper presents a numerical study of the ductile crack growth in specimens and cracked structure made in a X6 CrNiNb 18 10 German austenitic steel. The cracked growth is simulated with the Ji-G_fr approach : The crack initiation is related to a critical value of J (J_i) deduce from the link between J and stretch zone width prior to the propagation. The G_fr parameter represents the rate of the dissipated energy in the fracture process occurring during propagation. J_i and G_fr are determined from a tearing test on a CT25 specimen. The transferability of these parameters is first checked by the simulation of the crack growth in a tree point bending (TPB) specimen. The cracked propagation is also modelled in the case of a pipe with a circumferential throughwall defect submitted to a bending moment. A good agreement is found with experimental result, up to a crack extension of 10 mm each side of the initial defect. (orig.)