ESAB Knowledge center.
How to weld aluminum to steel
March 25, 2014
You can weld aluminum to most other metals relatively easily via adhesive bonding or mechanical fastening. However, in order to weld aluminum to steel, special techniques are required.
When metals such as steel, copper, magnesium, or titanium are directly arc welded to aluminum, very brittle intermetallic compounds start to form. To avoid this, you must isolate the other metal from the molten aluminum during the arc welding process. Here you'll learn about two of the most common methods for doing this successfully.
Bimetallic transition inserts.
Creating a bimetallic transition insert is a popular method used when welding aluminum to steel, and it's often used for producing welded connections of excellent quality within structural applications.
These inserts are best described as sections of material that are comprised of one part aluminum with an equal part steel or stainless steel already bonded to the aluminum.
The methods used to bond these dissimilar materials and form the bimetallic transition are usually rolling, explosion welding, friction welding, flash welding (or hot pressure welding), and arc welding.
To avoid overheating the inserts during welding, it's good practice to perform the aluminum-to-aluminum weld first. This also provides a larger heat sink when the steel-to-steel weld is performed.
The bimetallic transition insert method is commonly used to:
- Join aluminum deckhouses and steel decks on ships
- Weld aluminum tubing with steel or stainless steel tube sheets on heat exchangers
- Produce arc-welded joints between aluminum and steel pipelines
steel prior to welding.
Another method many use to successfully weld aluminum to steel is dip coating, also commonly referred to as hot dip aluminizing. This simply means that prior to welding the steel and aluminum together, the steel is first coated in aluminum.
Once coated, the steel member can be arc welded to the aluminum member, if care is taken to prevent the arc from impinging on the steel. A specific technique must be used during welding to direct the arc onto the aluminum member and to allow the molten aluminum from the weld pool to flow onto the aluminum-coated steel.
Another coating method for welding aluminum to steel, called brazing, involves coating the steel surface with silver solder and then welding them together using aluminum filler alloy.
Please note that neither of these coating-type joint methods are typically depended on for full mechanical strength and are usually used for sealing purposes only.
If you want to learn more about welding aluminum to steel, or if you have a question that wasn't
answered here, please feel free to contact us.