Fatigue assessment of laser beam welds between AlSi10Mg AM-structures and conventionally manufactured aluminum by local approaches

Abstract

The fatigue assessment of dissimilar aluminum materials is made by notch stresses for laser beam welded joints between additively manufactured AlSi10Mg and conventionally manufactured EN AW-6082 T6. The assessment is extended from the joint types of single side welded lap joints and peel T-joints both with an I-shape seam weld to lap joints with fillet welds on both sides. The results of notch stresses based on the von Mises stress hypothesis for lap joints with fillet welds exceed FAT 142 and even FAT 160 recommended for weld toe failure, assuming a slope of the design S-N curve of k = 5 in case of thin and flexible structures. Notch stresses of both joint types with I-shape seam welds are in good agreement. Recommended notch stress fatigue classes of FAT 160 or higher cannot be applied in a safe fatigue assessment for these joint types, since some lower stress values (for peel T-joints) are found. The scatter of an overall notch stress S-N curve for LBW joints with I-shape and fillet welds is increased.From the structural stress assessment of a LBW aluminum component, a sufficiently low difference in the fatigue life between the FE-based estimation and the experiment is obtained. However, this result is an outcome of a specific modeling and meshing approach. Consideration of multiaxial load cases or a general validation is not part of this study.