FEASIBILITY INVESTIGATION OF LASER WELDING ALUMINUM ALLOY 7075-T6THROUGH THE USE OF A 300 W, SINGLE-MODE, YTTERBIUM FIBER OPTIC LASER

摘要

Aluminum alloys are important structural materialsbecause of their high strength-to-weight ratio. Yetthey are some of the hardest metals to be laserwelded successfully and this is usually done at veryhigh laser power. This is due to their high reflectivityand complexity in heat treatment. This studyinvestigated the feasibility of using a 300 W, Single-Mode, Ytterbium Fiber Optic Laser for aluminumwelding. The objective is to explore an applicationarea with low power and low welding speed. Theresults show that, with proper control of weldingparameters, the success of aluminum welding can beachieved at considerably low laser power withminimal formation of typical welding defects(porosity, cracking etc.), since the fiber laser offersmuch better beam quality (M2 less than 1.05).However, the focusing becomes highly critical,because when a certain power density is exceeded itcan lead to defects, such as blowholes and porosity.The deepest penetration achieved was just over 1 mmat 300W and 2 mm/sec. Other welding processesachieve about three to four times deeper penetrationat the expense of seven times more power. Furtherdevelopment of this process may lead to a moreefficient use of power.