Study on full-penetration laser welding of aluminum alloy under electromagnetic field support and subatmospheric pressure

A vacuum chamber fitted with an oscillating electromagnetic molten pool support system was used to study the full-penetration laser welding of the A5083 aluminum alloy at various ambient pressures, magnetic induction intensities, and magnetic field frequencies. The weld formation characteristics, porosity susceptibility, micro-structure characteristics, and mechanical properties were investigated based on experiments and numerical simulations. The experimental results show that the ambient pressure mainly affects the width of the upper zone, the porosity, and the microstructures of the welded beads. When the ambient pressure is below 10 kPa, the porosity in the weld can be controlled to be below 1%, the microstructure of the weld is composed of small equiaxed grains with an average diameter of only 19.8 mu m, and the welding joint is comparable in strength to the base metal. The magnetic induction intensity can effectively suppress the irregular weld surface profile due to vapor ejection during the welding process when it exceeds the threshold. The magnetic field frequency can be optimized to control the weld shape. Appropriately applied alternating magnetic field can enhance the load-bearing capacity of the joint by preventing the weld root from sagging. The range of processes used to obtain high-quality welds is: ambient pressure 3-10 kPa, magnetic induction intensity 60-80 mT and magnetic field frequency 300-400 Hz.