Welding aluminium vs Welding steel: How they differ from each other

Most welders believe that aluminum is a difficult type of metal to weld compared to steel. That is the reason why most of them prefer to start out by learning to weld steel before moving on to aluminum. Unlike what other people know, welding aluminum is difficult because it simply uses a different method. For welders, it is important to understand these differences in order to achieve a good weld.

To give you an overview, here is a quick comparison between welding aluminum and welding steel. Learn more about how they differ from each other.

Properties of Aluminum and Steel

Aluminum and steel are two most popular materials used in welding. Each material has a distinct set of characteristics that makes it the right or wrong material for a specific job.

To have a good aluminum and steel weld, it is important to know about the metal’s chemistry, reduction of hydrocarbons and appropriate technique for the material. For example, the melting point of aluminum is 1,221 degrees Fahrenheit while for steel is 2,500 degrees Fahrenheit.

Furthermore, aluminium has an oxide layer that melts at nearly 3,700 degrees. This helps the aluminum to be corrosion and abrasion-resistant. Aside from that, it acts as an insulator where issues may arise.

When it comes to aluminum, its strength tends to increase as service temperature decreases. While steel, on the other hand, becomes more brittle as service temperature decreases.

Pre-treatment process

When it comes to welding aluminum, pre-treatment is critical. This is because aluminum can readily combine with hydrogen. Thus, it must be gradually raised to ambient temperature if it was stored in a cooler space. Aside from that, the aluminum should be cleaned with non-chlorinated solvents to remove the oxides.

On the other hand, mild and low-carbon steel is simple to work on. It does not need any specific pre-treatment method. But with high-carbon steel, heat-treatment is needed after welding. It is also more difficult to handle.

Metal inert gas welding is the most common welding technique used for both aluminum and steel. For aluminum, argon should be used as your shielding gas. While for steel, argon mixed with carbon dioxide should be utilised.

There are a lot of welding techniques that will work well on steel but not with aluminum. For instance, using oxy-acetylene torch welding may not work well with aluminum. This is because the metal can absorb hydrogen gas which leads to faults in the weld.


Welding requires utmost precision to ensure that there is a strong bond between the two objects. When welding aluminum and steel, it is important to prepare your materials first. Aside from that, it is also a must to wear proper protective equipment before you start.

When it comes to aluminum, there are some special procedures that must be followed to have a successful weld. Here are some steps on how to weld aluminum.

1. Before welding any piece of aluminum, it is vital to clean away the aluminum oxide on the material. This can be eliminated by wire-brushing, grinding or filing away the oxides.

2. Clean the filler rod to avoid getting a dirty workpiece.

3. To avoid unnecessary gaps in the joint, make sure to clamp the workpieces together as tightly as possible.

4. To make it easier to weld, it is important to preheat the aluminum workpiece. It can be done either by putting directly in an oven or using a propane torch to apply heat to the surface. The temperature should be between 300 and 400 degrees Fahrenheit.

5. To start the actual process, set the amperage of the welding machine. Use about 1 amp per 0.001 inch of the material’s thickness.

6. Prepare your workpiece in position. Extend the tungsten electrode not more than the diameter of the torch’s nozzle.

7. Create your electrical arc by pressing the button on the torch. If there is no button, then you can use the foot pedal to create an arc.

8. Melt the workpiece until it creates an ample-sized puddle. It should not be wider than the circumference of your filler.

9. Weld for about ¼ inch. Let it cool for a while before welding again. Do this to make your weld stronger.

Welding steel has a quite simple process compared to welding aluminum. Here is the basic procedure for welding steel.

  1. Before working on the material, clean the base metal first. Use a wire brush that is designed for steel and acetone. Rub it thoroughly to get rid of the impurities. This step is important to achieve a better weld.
  2. Secure the metal using fixtures and jigs.
  3. To start, use a welding machine to join thicker pieces of metal. MIG welding machine is recommended because it is fast and easy to use.
  4. Feed the filler wire through the torch. Then turn on the gas and begin welding.
  5. Position the torch at an angle of 30 degrees above the edge of the joint. Let the flame heat up the material. Do this until it forms ahead of liquid metal in the joint. Then move the torch forward so that it can fill in the joint.

When to use aluminum for welding

• If something lighter is needed – aluminum is the best material of choice if you need something lightweight while still being durable. One common example is when making vehicles such as cars and airplanes. Using aluminum for cars allow them to still move fast and maneuver as intended.

• If you don’t want rust or corrosion – if you are looking for something flawless and appealing, then aluminum is the right option. It is perfect to use for aesthetic purposes since it can be painted and will not rust for a while.

• If something more elastic is required – unlike steel, aluminum can bend despite all deformations. It also keeps intact and usable.

When to use steel for welding

• If something heavier is required – Basically, steel weighs about three times as much as aluminum. This makes it ideal for heavy and slow-moving applications.

• If durability is needed – generally, steel is more durable than aluminum. It also doesn’t bend like bend. Thus, you can enjoy its strength and resiliency.

• If insulation is necessary – when it comes to insulation, steel is better than aluminum.


To achieve a satisfactory weld, it is crucial to understand the different characteristics, properties, etc. of each metal. This is for you to know what welding techniques and pre-treatment procedures they require. Aluminum and steel are two different metals to weld. So it is important to have your research before using these materials.

If you want further assistance when it comes to welding your aluminium or steel, make sure to approach your trusted local metal fabrication experts.

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