Usually double cantilever beam (DCB) samples are tested following NACE Standard TM0177-2005 procedure. The standard establishes arm displacement limits as a function of steel grade.Material resistance to propagation of environmental cracks is expressed in terms of a critical stress intensity factor KISSC or K-limit values. However the increasing interest on material characterization in mild sour media imposes testing at higher arm displacements that can produce larger plastic zones at the crack-tip of DCB specimens. Therefore It is important to study the loading conditions that cause the loss of linear elastic response in DCB samples.In the present paper several elastic-plastic and linear elastic 3D finite element models of DCB geometry have been performed. The models consider a wide range of crack lengths to half specimens height (a/h) ratios and different material properties (different YS levels). The obtained results allow to correct the fracture mechanics parameters (Ks) of DCB samples due to elastic-plastic effects and to establish a criterion to determine the range of applicability of linear elastic fracture mechanics.