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The paper presents the results obtained on a fatigue study on the life extension ofnon-load carrying fillet welded joints loaded in bending at the main plate and with fatiguecracking at the weld toes of the attachment in the main plate and through the plate thickness.Results of the stress distributions at the crack propagation line at the weld toe obtained by a 2DFE analysis were obtained. These results were obtained using a elastic-plastic model, with theelastic-plastic cyclic stress-strain curve derived from LCF tests carried out in the base material.The residual stresses were measured at the surface, using X-ray diffraction and hole drillingtechniques. Very good agreement was obtained between the experimental residual stress and thecomputed values, using a 2D and 3D elastic-plastic finite element model of the hammer peenedprocess. The residual stresses induced by hammer peening at the weld toe were found to begreater along the longitudinal direction of the plate than in the transverse direction. The peakresidual stresses near the weld toe were found to be close to yield in compression, justifying thegreat benefit of hammer peening.