Joining similar and dissimilar material combinations by laser shock forming

摘要

This paper verified the feasibility of joining similar and dissimilar material combinations by laser shock forming. Typical joining defects and failure modes during the deformation process were also discussed. Neck fracture often takes place in the lower foil, which was subjected to serious joint shearing effect from laser-induced shock wave and hole edge of perforated sheet. Meanwhile, bottom fracture was more likely to occur in the upper foil, in which the direct laser shock pressure was quite large. Process windows of Cu/Cu/Ss combination and Cu/Al/Ss combination were acquired after conducting an array of experiments. The influences of laser energy and material properties on interlocking structure were investigated by analyzing cross-sectional material flow and measuring key structural dimensions. With the increase of laser energy, interlocks gradually increased while neck thicknesses gradually decreased. Under the same processing conditions, interlocks of Cu/Al/Ss combination were larger than that in Cu/Cu/Ss combination, while both neck thicknesses showed an opposite trend. Single lap shearing tests showed that mechanical strength and failure modes of joints were notably influenced by interlocking structure, a high joining strength can only be obtained under larger interlocks and larger neck thicknesses.