CONTROL OF MAGNESIUM LOSS DURING LASER-WELDING OF AL-5083 USING A PLASMA SUPPRESSION TECHNIQUE

A major problem of autogeneous laser welding Al-5083 is the loss of magnesium by evaporation of plasma formation. This consequently results in welds of low tensile strength and unacceptable porosity. A method has been developed to control plasma formation during welding resulting in satisfactory welds with little or no magnesium loss and porosity. Plasma formation was controlled by manipulation of a main gas jet in a shielding arrangement during welding. Shielding gas pressure needed to suppress the plasma was within an order of magnitude of the theoretically estimated pressure required to sustain a vapor filled 'keyhole'. The experiment was carried out using a 10 kw CW-CO//2 laser. A two-level factorial experimental design correlated the effects of the independent laser processing variables with as-welded alloy chemistry.