Laser Beam Cutting and Welding of Magnesium-Based Alloys

Using magnesium as base metal the lightest alloys can be produced which, although having low specific weights, demonstrate good strength properties. Magnesium alloys are of growing interest for applications in the automotive and aeronautics industries. Up to now casting and mechanical machining have been used as the most important processing techniques; therefore, first orientational cutting and welding investigations have been performed using CO₂ lasers in the power level of 1 kW and 6 kW. It turned out that the material can be treated using lasers without problems provided an appropriate handling was applied. Laser cutting has been investigated with oxygen and nitrogen as assistant gases; the best cut quality was obtained when using nitrogen. Applying a laser power of 1 kW (CO₂) cast magnesium of 9 mm thickness was cut with a speed of 0,2 m/min. The welding investigations showed that with relative low laser powers deep penetration welds can be obtained; for instance 4,5 mm with 1 kW and 18 mm with 6 kW laser power. The weld form factors are pretty high and values have been obtained which have been possible up to now only if using electron beam welding techniques.