Is It Possible to Weld Aluminum to Steel?

Is It Possible to Weld Aluminum to Steel?

Welding Aluminum to Steel Requires Special Techniques

You can weld aluminum to most metals easily through adhesive bonding or mechanical fastening. However, to weld aluminum to steel, special techniques are required. 

Directly arc welding metals such as steel, copper, magnesium, or titanium to aluminum produces very brittle intermetallic compounds. To avoid this, you must isolate the other metal from the molten aluminum during the process.  

There are three common techniques that can be used to successfully weld aluminum to steel. 

  • Bimetallic Transition Inserts 
  • Brazing 

Bimetallic Transition Inserts 

Creating bimetallic transition inserts is a popular method used when welding aluminum to steel. This method is often used for producing welded connections of excellent quality within structural applications. 

The bimetallic transition inserts are sections of material comprising of one-part aluminum with equal part steel or stainless steel. The inserts are already bonded to the aluminum. Various methods are used to bond these dissimilar materials and form the bimetallic transition. These methods include rolling, explosion welding, friction welding, flash welding (or hot pressure welding), and arc welding. 

Arc welding the steel and aluminum bimetallic transition inserts is done through normal methods of GMAW or GTAW. One side of the insert is welded steel to steel. The other is welded aluminum to aluminum. 

Performing an aluminum-to-aluminum weld first helps prevent the inserts from overheating. 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 

Dip Coating Steel Prior To Welding 

Another method many use to successfully weld aluminum to steel is dip coating. This is also commonly referred to as hot-dip aluminizing. In this method, the steel is coated with aluminum prior to welding the steel and aluminum together. 

Once coated, the steel member can be arc welded to the aluminum member. Care should be 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. The technique also allows the molten aluminum from the weld pool to flow into the aluminum-coated steel. 

Brazing Steel 

Another coating method for welding aluminum to steel is brazing. It involves coating the steel surface with silver solder. The pieces are then welded together using aluminum filler alloy.   

Please note that neither of these coating-type joint methods (dip coating, brazing) are typically depended on for full mechanical strength. They 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 was not answered here, please feel free to contact us