Influence of waveforms on Laser-MIG hybrid welding characteristics of 5052 aluminum alloy assisted by magnetic field

Abstract

Laser-MIG hybrid welding of 5052 aluminum alloy assisted by magnetic field with three waveforms was performed. The results showed that compared to that without a magnetic field (NMF), the weld depth was increased by 46.3%, 45.1% and 22.4%, respectively, with the sequence of the static magnetic field (SMF), Triangular-wave magnetic field (TWMF) and Sine-wave magnetic field (SWMF), due to different dispersing effect of magnetic fields on welding plasmas. The similar effect of magnetic field with three waveforms on stirring molten pool during solidification led to almost the same refinement of grain size and randomness of grain orientation. Additionally, magnetic fields were found to improve stability of keyhole, prolong solidification time of molten pool and provide more escaping channels of bubbles, the porosity rate of weld was thus reduced from 7.80% to 3.46%, 2.11% and 0.82% when SMF, TWMF and SWMF were employed, respectively. As a result, the hardness and tensile properties of fusion zone under magnetic field with three waveforms were significantly improved and the highest tensile strength was obtained in the case of SWMF. Among the three types of magnetic fields, SWMF was the best in terms of reducing the weld porosity and increasing the tensile strength.