In recent years the failure behavior of power beam welds have been investigated by means of Finite Element Analysis. In order to determine the local stress state around a crack tip before the crack initiation occurs, the J-Q-M concept has been applied [
]. A Q-factor is added to the crack driving force, expressed as a J integral and account is taken of the effect of strength mismatch by the M factor. As a results the recommendations for the application of constraint corrections have been derived. Additionally the stable crack growth and crack path deviation have been simulated by using the GTN damage model.