There are different welding techniques, specifications, shielding gases as well as different pre-weld and post-weld processing compared to steel. The regular welding processes might night alterations for welding aluminum. The first thing you will have to do is select the welding process.
The reasons why aluminum welding is difficult
Before moving on with the different welding processes for aluminum, you should know why it is difficult to weld aluminum. One of the difficult areas is filler material as some of the alloys cannot be welded without filler materials. For example, 6061 alloys would crack if you fail to use filler material. Also, you have to select the right filler material for the job. You cannot use 6061 filler metal for 6061 alloys. Go with 5356 or 4043 aluminum filler material is more suitable.
Compared to steel, aluminum has greater thermal conductivity. The heat created during the welding gets dispersed quickly. Due to this full penetration might not happen until the welding process has progressed a bit further. This is called cold start and you have to ensure that it doesn’t happen when you weld aluminum. Another issue that arises due to thermal conductivity is bigger craters. By the time welding is about to end, there is more heat than the initiation. This could disperse in aluminum and create a large crater. Aluminum is prone to crater cracking, so fill the craters so your weld does not end up in a disaster at the end. There are pre-weld and post-weld processes for aluminum welding.
Welding Types of Aluminum
Listed below are the four welding processes for aluminum:
- Laser Beam Welding and Electron Beam Welding
- Resistance Welding
GTAW/TIG is one of the most preferred methods for welding aluminum. GTAW stands for gas tungsten arc welding, which is commonly known as TIG. GTAW does not require mechanical wire feeding and could lead to feedability issues. The welder has to feed the filler material into the puddle himself. As the process is neat, it keeps aluminum away from getting polluted.
GMAW stands for gas metal arc welding and we know it as metal inert gas (MIG) welding. It is another suitable option for welding aluminum. This method generally possesses higher deposition rates. It also has faster travel speeds than GTAW.
It uses a mechanical wire feeding system. Due to this, a push-pull gun or a spool gun is needed to make the aluminum wire feeding possible. See that you don’t use 100% CO2 or even 75% Argon/25% C02 shielding gas. This gas works for steel, but aluminum cannot handle the reactive CO2 gas. See that you follow the manufacturer’s recommendation for gas.
Laser Beam Welding and Electron Beam Welding
Beam welding is also appropriate for welding aluminum. As the power density of beam welding is high, cold starting is not an issue. But light reflectivity could be a matter of concern with laser welding. Shielding gas optimization plays an integral role in preventing sponginess.
Electron beam welding, on the other hand, does not have these issues as it does not uses light as an energy medium.
Resistance welding could work out when welding aluminum. But due to aluminum’s electrical and thermal conductivity, issues might arise. You would need to follow special tips as well as resistance welding equipment and welding gear including a sturdy welding helmet, like the ones found at Welding Corner, to overcome any issues.
Some processes are not suitable for welding aluminum at all. Any welding process that involves using a flux like submerged arc welding, flux-cored arc welding, and stick welding do not bring any results and are not effective means of welding aluminum. These can also lead to an increased amount of permeability.