The Challenges of Welding Aluminium

The Challenges of Welding Aluminium
November 2, 2020 admin
Sheet Metal Fabrication

Aluminium is a fantastic material for building and construction. Its key assets? It is durable, flexible, light-weight, strong and resistant to corrosion. But due to its unique assets, aluminium is much more challenging to work with than steel and other commonly used materials. It is a sensitive metal that can easily bend, break and change its colour, which is why you need to be familiar with special welding techniques. Here are some of the common problems and possible solutions for them!

 

Aluminium Cracks Easily

 

One of the most common challenges to aluminium fabrication Perth engineers are facing, is its unstable chemical composition. Its strength decreases as temperatures get higher, which makes it more brittle than other metals.

 

Problem:  Welding can cause cracking and breaking. How? While hot cracking occurs due to aluminium’s chemical composition, stress cracking results from mechanical pressures. Both types of cracks can cause weld failure.

 

Solution: You can prevent hot cracking while welding aluminium by using a filler metal which is less prone to heat and is much less brittle.

 

It Has a Low Melting Point

 

There are many advantages of using aluminium in mechanical engineering Perth-wide. It is light, resistant to corrosion, and it has high conductivity, formability and recyclability. However, aluminium can’t withstand high temperatures because it has a low melting point. It is 660 degrees Celsius, compared to 1,500 degrees for steel. Its oxide layer is harder and melts on 2072 degrees, which helps aluminium resist abrasion and corrosion.

 

Problem: Unlike other common materials used in construction, aluminium is very likely to bend and break during the welding process.

 

Solution: You can avoid these problems if you opt for a pulsed GMAW welding process. The power source combines high peak current and low background voltage of 30-400 times per second. This method prevents distortions in the metal caused by extreme heat.

 

It is Highly Porous

 

Metal fabrication Perth businesses are using aluminium because it is versatile, low-maintenance and cheaper than steel, but one of the most common challenges is its high porosity.

 

Problem: During the welding process, gasses get trapped in the weld pool due to turbulence. Aluminium then cools before the gas gets a chance to escape, which causes discolouration. Porosity typically occurs because air or shielding gasses slip in and stay inside the weld pool.

 

Solution: You can do a few things to prevent discolouration caused by the porosity of aluminium:

  • The first step is to ensure that both base metal and filler metal are dry and clean. You can use a dry cloth and a solvent to remove oil, paint or anything else that can get caught up in the weld. You should also brush the weld joint using a brush designed especially for this.
  • Aluminium used for the base should stay in a room temperature for 24 hours before you start welding because this prevents condensation from forming on the surface.
  • It is also important how you store filler metals. They should be kept unpackaged in a heated room as this prevents hydrated oxide from forming on the surface.
  • Purchase filler metals from reputable manufacturers.
  • Finally, you can also buy a low-dew-point shielding gas which is fantastic protection against aluminium’s porosity.

 

Despite all the downsides and challenges, aluminium is a high-quality material frequently used instead of steel and other metals. Once you know the right procedures, welding aluminium is no longer a problem. Remember that it is all down to chemistry and that the key is a mix of the right base material and filler metal.