How does Thermite Welding Work?

Last Updated on May 17, 2022

Part of becoming an expert welder is familiarizing yourself with all the numerous forms of welding techniques used around the world today. If you’re a welder who wants to learn about the different forms of welding, or just some person keen on learning more about this field, this article is for you. Keep reading as we cover all the concepts you need to know to understand the fundamentals of thermite welding.

What is thermite welding?

Thermite welding refers to a process that creates high, focused heat by combining iron oxide with aluminum powder to create a ” thermite” reaction that fuses two metals together. In this process, thermite is used to rapidly heat the metal components, which are then forced together to form a pool of molten contents that solidify over time.

This is a form of friction welding that does not need any flux. Additionally, the procedure does not need any prior cleaning or preparation of the surfaces, making it a simple and rapid approach that won’t require as much time as most other metal joining processes would.

Thermite Welding – A Closer look at How it Works

Thermite reactions are carefully localized, exothermic reactions of metal powders that generate ample heat to melt down metals to create a weld. These reactions begin with the mixing of two substances: metal oxides with iron (III) oxides. When combined, these two substances generate heat without even needing a flame.

This form of welding is successfully executed by combining the aluminum powder with an appropriate metallic fuel source, like zinc dust or strips of magnesium. After adding a little quantity of water into the mix, it is lit up by a gentle flame. When sufficiently heated, aluminum reacts aggressively, creating ample heat to melt down any metals in its vicinity.

This process is repeated if either of the two substances has been fully consumed. Two distinct forms of thermite reactions may be employed to join metals. The first technique is called “gasless welding,” in which magnesium is used for fuel while aluminum or zinc (in powder form) is used as metal oxide. This sort of reaction is self-sustaining in the absence of air (and oxygen).

When is Thermite Welding Required?

This form of welding is most commonly used today when large numbers of robust and durable welds are required. Additionally, it is often used as a substitute for other forms of welding, including arc welds and GTAW (gas tungsten arc welds).

This form of welding also proves to be quite effective on thinner materials which makes thermite welding an increasingly more regulated operation. This is particularly beneficial when putting pieces of varying sizes jointly or when the completed product requires very tight tolerances.

What welding equipment do I need to thermite weld?

A discussion on the kind of equipment that you will require to perform a thermite weld is an essential part of this discourse that can’t be ignored. Also, bear in mind that the list of the equipment stated down below only states the additional material you require for this form of welding. The classic tools for all forms of welding, of course, remain constant.

If you want to start executing thermite welds, you might want to fetch yourself a pen and a piece of paper- it is time to make a shopping list:

  • To start with, you will need to get yourself some aluminum (in powder form) alongside iron oxide since they make up the thermite charge.
  • Next, you will need a paper or some metal covering to encase the aluminum inside it.
  • Then, you will need a crucible – the part capable of withstanding extremely high-temperature levels that holds the thermite materials. The exothermic process of this welding takes place inside the crucible.
  • In addition to this, you will also need a mold that will hold the section around the area that will be welded.
  • Finally, a taping device will be required, which helps pour the melted form of metal from the crucible into the mold.

Why should you use thermite welding?

Now that you’ve learned the basics of what thermite welds are and what equipment you need to perform them, the next logical thing is to understand why you should opt for thermite welds. The discussion in this section of the article covers a brief answer to this question.

Thermite Welds are pretty straightforward, easy to execute, and time-saving relative to other forms of welding techniques. In addition to this, this process doesn’t even require the welder to clean up the metal surfaces before starting the procedure, so you can be sure that this process won’t waste any of your time at all.

Another thing that should attract you about thermite welding is the fact that it is a flux-less type of friction-based welding that can work just fine without the use of air or O2 gas. This fact makes this entire process relatively a lot more environmentally friendly compared to others, so it should make it to the list of reasons that make you want to opt for this type of welding.

Is thermite welding safe?

In general, welding is a task with many hazards. If proper measures are taken, and the correct safety equipment is worn at all times, the chances of you getting injured are significantly reduced. So, while this process is generally as safe as welding gets, it should never be performed (at least not without supervision from an expert) by someone who has never done it before.

Additionally, you should never use this type of weld if you’re doing it on any form of unrefined metals like recycled metals or aluminum dross. Keep these pointers in check, and you should be good to go.


To conclude, thermite welding is an extremely safe, easy to perform, and environmentally friendly process that creates heat using iron oxides with aluminum powder to create thermite reactions that facilitate this weld.

To properly execute a thermite weld, you will need the following pieces of equipment in addition to the standard list of welding equipment:

  • Aluminum powder with iron oxide.
  • A metal casing
  • A mold
  • A crucible, and finally
  • A taping device

In addition to this welding equipment, you would also do well to invest in some safety gear for when you perform the welding to steer yourself clear of any potential hazards you might get exposed to.