Overcoming Surface Roughness by Using Beam Oscillation to Laser Weld Laser Cut Steel
A. Kumar, S. Gumma and S. Neogy
The feasibility of achieving a sound laser weld between laser cut IS2026 carbon steel specimens having higher areal roughness parameter Sz (maximum height) by utilizing an oscillating beam from a fiber laser operating in continuous wave (CW) mode is reported in this work. A gap of around 200 μm between the mating surfaces of the laser cut specimens was bridged without using any filler material during LBW. Welds made by this technique were found to be radiographically acceptable in terms of absence of porosities and other defects. Different microstructural zones with varying hardness were noticed across the laser welded joint cross-section. The mechanical properties of the weld joints made with different values of Sz were found to be almost identical. Digital image correlation (DIC) studies during tensile testing showed occurrence of fracture in the base metal of the specimen away from the weld joint. The proposed welding process with increased tolerance to surface roughness of the laser cut specimens could potentially increase the production yield and the quality of laser cut-welds in an industrial environment.
Keywords: Fibre laser, IS2026 steel, laser cutting, laser beam welding (LBW), laser cutting/welding, laser beam oscillation, weld quality, surface roughness, tensile strength