In welded joints subjected to multiaxial fatigue, it is of interest to determine both the time to crack initiation and propagation to understand what controls fatigue life of the element. It has been shown that the mean stress state at the weld toe is of great importance in both initiation and propagation stages of welded specimens. Since no such measurements have been made on S690QL specimens, the objective is to quantify the residual stress field and its stability at the estimated point of initiation on two types of specimens at two different times during multiaxial fatigue testing. Results will then be used to model specimens’ behaviour with the help of elasto-plastic finite element. Non-destructive neutron diffraction is the only choice for these measurements, since it makes possible stress measurement in same specimens at various stages of their fatigue life.