Numerical Simulation of Crack Propagation in Al6061 Laser Welded Joints

In this paper, numerical simulations and experimental tests are performed on the Al6061 laser welded joints. In order to identify the dimensions of different weld regions, hardness tests are performed across the welded joint. Mechanical properties of different weld regions are obtained from tensile test results of flat specimens extracted from the base material (BM), the fusion zone (FZ) and from the heat affected zone (HAZ), respectively. Fracture toughness tests are performed on compact tension specimens (C(T)) with the initial crack located in the BM, in the center of the FZ and at the interface between the FZ and the HAZ, respectively. The Rousselier model is employed to study the ductile fracture behavior of Al6061 laser welded joints numerically. Based on metallographic investigations and numerical calibration results for notched round specimens, the initial void volume fraction () and the average void distance (lc) for the Rousselier model can be fixed for the BM, the FZ and the HAZ. The same Rousselier parameters are used to predict crack propagation in C(T) specimens with different initial crack positions. Computer simulations are compared to the experimental results in terms of force vs. Crack Opening Displacement (COD) as well as fracture resistance JR curves. It is concluded that the Rousselier model can predict well ductile crack growth in the weld joint.