Simulation of the fracture behavior of a S355 electron beam welded joint by cohesive zone modeling

In this paper, the cohesive zone model is used to study the fracture behavior of an S355 electron beam welded (EBW) steel joint. Mechanical properties of different weld regions are derived from tensile tests of flat specimens, which are extracted from the respective weld regions. The cohesive zone model which was applied to predict the damage of the welded joint has two independent parameters, i.e., the cohesive strength T0 and the cohesive energy Γ0. For a pure mode I situation, based on the tensile test of notched round specimens, the cohesive strength T0 can be fixed, both for the base material (BM) and for the heat affected zone (HAZ). With the fixed T0 value, the cohesive zone model is adopted to predict the crack propagation on compact tension (C(T)) specimens with the initial crack located at different weld regions with different cohesive energy values Γ0. Numerical simulations about the first unloading stage are performed which will help to select the right traction-separation law (TSL). The numerical simulation results match the experimental ones well in terms of force vs. Crack Opening Displacement (COD) curves as well as fracture resistance (JR) curves.