Investigation on shear and tensile strength of laser welded electrical sheet stacks

Abstract

We report on an experimental study of the shear and tensile strength of electrical sheet stacks welded using a multi-mode fiber laser. The objective of this study is the optimization of the strength with the lowest possible weald seam size to minimize eddy currents. To achieve this, the influence of laser power and weld contour is investigated with the strength being tested under different mechanical load configurations. In the studied range of laser power up to lkW, both the weld seam width and depth increase linearly with power. The shear strength increases strongly with the laser power, while the studied weld contours have no significant effect on the shear strength. The shear strength of the weld seam itself is calculated to 260 MPa and scales well with the weld seam cross section area, which in turn is influenced by the laser power. The tensile strength of the weld seam is determined between 180 MPa and 565 MPa depending on the specific weld contour applied. The fracture behavior of the sheets reveals a brittle behavior for the tensile test and ductile behavior for the shear strength. Overall, the experimental results imply that laser heat conduction welding is a suitable tool for stack welding of electrical sheet when small weld seams are necessary.