Influence of Air Gap Size to Mechanical Properties of Laser Welded Lap Joints

Abstract

The paper is focused on the effects of air gap size to mechanical properties of laser welded lap joints. Structural steel plates of 3 mm thickness were used in the laser welding experiments. The laser welding experiments were conducted at two very different energy inputs (EI) of 60 and 320 J/mm. The weld geometries were investigated using optical microscopy. The shear strength of the lap joints was evaluated by uniaxial tensile tests. Results showed that with low EI of 60 J/mm the size of air gap had significant effect on the width of the interface as the larger air gap size increased the width of the interface. At high EI of 320 J/mm, the width of the weld at the interface did not change significantly as the air gap increased. The hardness of the weld metal was greater than the hardness of the base material at both EIs. The shear strength of the joint increased significantly with low EI of 60 J/mm, as air gap size increased. The size of the air gap did not have a large effect on the shear strength of the joint with higher EI of 320 J/mm.