Feasibility investigation of laser welding aluminum alloy 7075-T6 through the use of a 300 W, single-mode, ytterbium fiber optic laser

Aluminum alloys are important structural materials because of their high strength-to-weight ratio. Yet they are some of the hardest metals to be laser welded successfully and this is usually done at very high laser power. This is due to their high reflectivity and complexity in heat treatment. This study investigated the feasibility of using a 300 W, Single-Mode, Ytterbium Fiber Optic Laser for aluminum welding. The objective is to explore an application area with low power and low welding speed. The results show that, with proper control of welding parameters, the success of aluminum welding can be achieved at considerably low laser power with minimal formation of typical welding defects (porosity, cracking etc.), since the fiber laser offers much better beam quality (M2 less than 1.05). However, the focusing becomes highly critical, because when a certain power density is exceeded it can lead to defects, such as blowholes and porosity. The deepest penetration achieved was just over 1 mm at 300W and 2 mm/sec. Other welding processes achieve about three to four times deeper penetration at the expense of seven times more power. Further development of this process may lead to a more efficient use of power.