Can You Weld Aluminium To Steel With A MIG Welder? Answered

With a density of about 2.70 g/cm3 compared to steel’s range of 7.75 to 8.05 g/cm3, aluminium (and its alloys) are significantly lighter than steel. This indicates that steel is roughly three times heavier than aluminium for a given volume. Learn if you Can You Weld Aluminium To Steel With A MIG Welder?

Steel is used in a variety of structural applications across several sectors. Steel has a large weight penalty attached to it because of its density. New environmental legislation now requires transport industries to adhere to severe limitations on greenhouse gas emissions.

Getting a vehicle’s structure lighter is one approach to help reduce emissions. The industrial importance of replacing different steel buildings with aluminium alloys has increased. In many applications, it is necessary to link the two materials because it is only sometimes possible to replace the steel structure with aluminium alloys completely.

Aluminium alloys can be easily attached to steel using adhesive bonding, mechanical fasteners, or brazing. However, welding is recommended when higher structural integrity is required. However, it is challenging to fuse aluminium alloys with steel.

Can You Weld Aluminium To Steel With A MIG Welder?

Aluminum And Steel Should Not Be Directly Welded Together. Attempting to fuse aluminium and steel directly is never a smart idea. Steel and aluminium alloys cannot be directly bonded since they have different metallurgical and physical characteristics. First, steel has a melting point substantially greater than aluminium.

Weld Aluminium To Steel With A MIG Welder

Additionally, because these metals are insoluble with one another, a weak joint results when they flow together while they are still in a molten condition. Steel and aluminium cannot be directly welded together in any industrial application due to the brittleness and fragility of these junctions. The joint would immediately break down.

But is it impossible to weld steel to aluminium? The response is “no.” Steel and aluminium can be welded together while reducing intermetallic development thanks to a bimetallic insert.

Why You Can’t Weld Aluminum To Steel?

The fact that the melting temperatures of the two metals are too high prevents you from welding steel to aluminium using the welder you have in your garage. Here is what occurs when you attempt to TIG weld the two metals together, just to put an end to any debate:

I finally settled on a steel filler. Before the steel created a puddle, the aluminium beneath it was already melting. To make up for that, I added tons of filler made of steel to bring the two materials together.

Why You Can't Weld Aluminum To Steel

Steel melts at about 2700 F, while aluminium melts at about 1200 F. That typically means the steel will begin to shine before the aluminium has melted away. The metal won’t fuse, even if you can get it to pool together. You’ll receive globs of steel only tenuously held together by clumsy, useless aluminium.

It required no force to separate this. The metals did not fuse, even though it appeared as though the substance had globbed together (that’s a technical term).

Aluminium and steel’s differing thermal properties are another factor that makes this ineffective. When heated, aluminium will expand nearly twice as much as steel. As a result, the welded area is liable to split under pressure when the metal cools.

There are a ton of other scientific explanations for why welding steel to aluminium doesn’t work, including various lattice changes, subsidiary precipitates, and differing thermal conductivities.

Transitions Between Two Metals

The most typical applications for this system are in pipelines, heat exchangers, and ships.

It is a steel-sided insert with an aluminium-sided surface. They are thick enough to weld the steel side to steel and the aluminium side to aluminium using a standard GMAW or GTAW procedure.

Pre-bonding of these inserts often involves hot rolling or hot pressure welding (explosion welding). The connections welded with these inserts are incredibly strong and can withstand a surprising amount of strain. According to some MIL specifications, these bonded inserts are expected to have at least 1/4 the tensile strength of aluminium, while they frequently measure closer to 1/2.


To be clear, doing this correctly does need some talent. Brazing might be an option instead of welding when you need to link steel and aluminium.

Brazing will have a different strength than explosive welding, though. There must be a lot of surface area for the pieces to stick together, and a tight mechanical fit will help keep everything together.

Here is a briefing on how to braze, presuming you already know how it functions:

  • The steel should first be wetted with a 56% silver braze.
  • Join the aluminium to the wetted steel by brazing with an alloy made of aluminium, such as Aluxcor 4047.

This two-step approach will give you better outcomes than a single-stage brazing technique. The braze is quite soft, and you won’t get as much gripping force as the single-stage brazes.


Using epoxy or another bonding chemical may work for you, even if this won’t offer you a particularly strong connection.

Again, a large surface area is necessary for this to function successfully, but a simple tube of JB Weld might be all you need to complete the task. Take your time cleaning both pieces completely; ideally, scuff up the surfaces that will be bonded for improved holding strength.

There are also some more expensive goods available. Although the 3M industrial structural epoxies are excellent, they can be pricey and have lengthy cure times.


This isn’t a word I made up on the spot. Most frequently, an aluminium-silicon alloy is used in the hot-dip process to aluminize steel, a metal. Although there are other approaches, such as galvanic coating, the hot-dipping technique is the most popular. This method cannot join huge steel parts with huge aluminium ones.

I bring it up since some inaccurate information about it is circulating online. A few websites claim fusing an aluminium block with aluminized steel is possible. Not at all. The only thing you can do is weld normal steel to aluminium steel.

The thin aluminium coating has long since burned away when you reach a sufficient temperature to melt the underlying steel. It could be more effective.

Automatic Fastening

Please utilize mechanical fastening. Aluminium and steel can be joined using just a few items from your local hardware shop.

Mechanical fastening is the best, most affordable, quickest, and simplest method for fusing various materials, whether you use bolts, rivets, folded seams, or anything else that takes your fancy.

Electrical Corrosion

This is something to remember while handling metals like steel and aluminium. Steel is typically prone to rusting, but aluminium is typically thought to be corrosion-resistant.

But if you combine the two metals and add salt water, the aluminium will experience substantial corrosion due to galvanic corrosion. The aluminium serves as an anode, the steel as a cathode, and an electrolyte, such as salt water, facilitates ion migration. The aluminium anode oxidizes as a result of this.

Reasonable explanation: If the aluminium is near saline water, it will rust where it hits the steel. This is a minor issue in many applications. However, if the surroundings contain salt (including road salt on cars), you may experience issues.

The remedy is to paint or cover the two items in plastic to isolate them and stop any electrical current from flowing between them. To be sure you’ve correctly isolated the metals, use the continuity tester on a multimeter.

Safety Tips When Welding Aluminum To Steel

Aluminum is a unique metal with special welding requirements due to these characteristics. To guarantee a safe working environment, extra safety measures must be taken. While welding aluminium to steel, keep the following in mind:

  1. The look of aluminium doesn’t change when heated: Aluminum doesn’t alter in appearance as it is preheated or heated during welding, making it difficult to tell when it is hot or cold. Additionally, compared to steel, aluminium has a higher heat conductivity. So, to lower the danger of injury, wear leather gloves while welding aluminium to steel.
  2. The welding of aluminium and steel may result in an electric shock: Welds made of aluminium and steel may deliver an electric shock. So, to protect yourself from the risk of electrical shock, you need a welding system that is properly grounded and well-insulated.
  3. Due to its strong reflectivity, aluminium Radiated heat is a common issue when welding steel, but it’s also a concern when welding aluminium. Due to the high reflectivity, welding aluminium to steel carries a significant risk of light-related accidents. Light-blocking drapes or long sleeves can help limit this exposure.


Yes! You can weld aluminium to steel with a mig welder. Aluminium and steel can be welded together, but the procedure is difficult and demands high professionalism. It is challenging to weld the two metals together since they are dissimilar in several ways, including thermal conductivity, melting point, and metallurgical qualities.

Despite the difficulties, welding aluminium to steel is still required to increase steel’s structural and other uses that call for lighter metals. Due to the differences in characteristics, traditional TIG, MIG, or arc welding cannot join the two.

Aluminium and steel metal inserts are used in bimetallic transition insert welding to link the two metals. You can also dip-coating, dipping steel into the aluminium to coat it completely.

Because molten aluminium doesn’t touch the steel during welding, a strong weld is produced, making welding possible. That’s all I have on Can You Weld Aluminium To Steel With A MIG Welder?

Frequently Asked Questions

How are aluminium and steel joined during welding?

For structural purposes, the optimum method of welding steel to aluminium is unquestionably using a bimetallic transition insert. It produces a weld of exceptional quality that is equally as strong as a bond between two pieces of steel or aluminium. An actual bimetallic transition insert is what it says it is.

What happens if steel wire is used to MIG weld aluminium?

By the time the steel melts, the aluminium will be liquefied thanks to arc welding. In addition to producing a brittle compound, arc welding the two metals together would not result in a powerful fusion.

How should aluminium and steel be joined?

Mechanical fasteners, Adhesive bonding, and brazing are all viable options for joining aluminium alloys to steel, but welding is preferred when strength and durability are paramount.

What results from the combination of aluminium and steel?

The electrons from the aluminium will start to transfer into the stainless steel when aluminium and stainless steel are used together in an assembly. As a result, the metal starts to deteriorate. The metal deteriorates significantly more quickly as a result of its weakness. The stainless steel may last longer as a result of this.

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