Economic gas transportation over long distances requires the use of high pressure and consequently the use of high strength steels such as grade API X100 which is investigated in this study. This steel is produced using Thermo-Mechanical Controlled Process (TMCP) as thick plates which can be rolled into large diameter tubes. The resistance to ductile crack propagation of these new steels must be determined to access the integrity of pipelines. This is done using Charpy tests, for which the upper shelf energy (USE) is determined, or drop weight tear tests. The purpose of this study is to establish unified constitutive equations able to represent the plastic and rupture behaviour of plates and tubes; the model must account for plastic anisotropy (induced by the production process) and for the pre-strain resulting from rolling plates into tubes (about 2% [
]). To illustrate the pre-strain effect [
], load-displacement curves issued from instrumented Charpy tests for the plate and the tube for two configurations (L-T and T-L) are reported on Fig. 1 where the value of corresponding USE are given. The maximum load is obtained for the tube (Fig. 1a T-L direction) due to pre-strain. However, for the T-L solicitation a sharp drop of the load in the case of the tube is observed once the ductile crack has initiated. This results in a strong decrease of the USE for the tube.