TIG Welding of Aluminum Alloys
Tungsten inert gas (TIG) welding is a welding process that uses a non-consumable tungsten electrode to produce the weld. TIG welding is also known as Heli-arc welding and is frequently used to join thin sections of aluminum and other non-ferrous metals such as magnesium and copper alloys. This process has advantages over other welding processes such as more precise and easier control of the weld joint and uniform weld quality. It is also suitable for welding alloys of virtually any chemistry such as aluminum alloys, copper alloys, magnesium alloys, nickel alloys and steel.
Because of their low melting point and corresponding thermal conductivity, aluminum alloys are one of the difficult metals to weld. TIG welding is one of the best processes for welding most aluminum alloys due to its excellent control over weld pool and arc. TIG welding is mostly used for welding aluminum sheets of varying thicknesses. It is also used for welding aluminum structures and components such as frames, tubes and piping.
The welding process begins with the proper preparation of the weld joint, which includes cleaning the surface of contaminants such as oil or paint. Grooves are sometimes cut into the joint to improve weld quality and aesthetics. When welding thick sections, a filler rod may be needed. The TIG welding process involves the manual feeding of a tungsten electrode into a welding arc. An inert gas such as argon is used to shield the weld pool from contamination. The arc temperature is usually between 5,600 °F and 6,000 °F and the welding process is considered to be one of the slowest amongst all the welding processes.
The major issue with regard to weld quality while TIG welding aluminum is porosity of the weld. This can be caused due to improper cleaning of the surface or insufficient shielding of the weld pool. It is also important to ensure that the correct weld parameters are maintained to get the desired weld quality. Too low an amperage will lead to incomplete melting of the base material and too high an amperage will lead to excessive heat input and excessive burn-throughs.
TIG welding of aluminum alloys offer several advantages such as good weld joint quality and strength with no or minimum distortion. It is used for high quality welding, especially of thin aluminum sections that require very precise weld quality. This process does not require many potentially hazardous chemicals, sparks or fume. It is also extremely useful for welding within confined areas and welding of critical components of the aircraft industry.
However, TIG welding of aluminum alloys is limited to welding very thin sections and is relatively slow as compared to other welding processes. It is not considered suitable for welding large sections. The weld joint may also suffer from splatting and high mechanical stresses, making it important to ensure high quality of the weld joint at all times.
Despite the limitations, TIG welding is an excellent welding process for aluminum alloys, providing excellent weld quality and joint strength. If used correctly, it can provide reliable, strong and durable weld joints that can withstand high loads and impact.
