What is Dissimilar Metal Welding?

A common question that we are asked by our customers here at SPI Lasers is “what is dissimilar metal welding?” Given that the term dissimilar suggests that the metals in question are extremely different, one is forgiven for thinking that it must surely be a complicated and difficult process to weld these metals together.

However, the term itself can be a little misleading, and the development of fiber lasers has seen the process become easier than ever. Interested to hear more on this highly useful and industry-changing process? You’ll find everything that you need below.

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The definition of dissimilar metal welding

This is a process which involves the joining together of two metals that possess different chemical or mechanical properties, and so aren’t necessarily a natural fit for each other. The reason the term can sometimes be slightly confusing is because it doesn’t only involve two completely different metals, such as aluminium and steel.

Dissimilar metal welding helps metals with different properties be joined together

Dissimilar metal welding helps metals with different properties be joined together

In fact, two metals with the same name can be welded together, but if they have different core properties, they are classed as dissimilar metals. For example, you can weld two austenitic steel metals together, but they may still be different enough to be considered dissimilar.

The welding process itself leaves a strong and permanent joint between the two metals, essentially leaving behind one final product. We’ve covered more on the specific process itself in the section below.

How does the process work?

This welding process works in almost exactly the same way as if you were welding two similar metals together. Using a laser beam which is precisely focused on the metals, you melt each of the metals together until they form one connected joint. If the two metals are not two wildly dissimilar, such as if you were using two austenitic steels as we mentioned earlier, the two will often join seamlessly together.

Stainless steel is one of the most commonly used metals

Stainless steel is one of the most commonly used metals

What factors need to be considered?

These are the factors that you must consider when performing the dissimilar metal welding process, and will affect your decision as to how easily two dissimilar metals can be joined.

  • Solubility – This refers to a metal’s ability to dissolve in a solvent. Both metals must be able to dissolve together
  • Intermetallic compounds – These will be formed in the transition zone during the welding process, and exhibit metallic bonding
  • Weldability – Based on the solubility and intermetallic compounds of two metals, you can work out the level of weldability between the two
  • Thermal expansion – How much the shape of your metals will change when a temperature is applied
  • Melting rates – The point at which your metals will melt
  • Corrosion – If two metals are extremely different on the electrochemical scale, then corrosion could occur
  • Endservice conditions – What are the conditions that your dissimilar metals will be operating within?

It’s incredibly important to consider each of these factors before you begin any process to ensure you get the weld correct.

Looking for more information?

We hope that the information here has helped to explain a little more on this highly innovative and useful process, and why it is so crucial to not only hundreds of industries around the world, but also to its billions of people too! From the smartphones that we use every day to the transport that gets us to work, this process has become a hugely vital part of modern industry and manufacturing.

If you have more questions on dissimilar metal welding, or about our range of pulsed fiber lasers or CW lasers, please don’t hesitate to get in contact with us. You can call us on +44 (0) 1489 779 696 or contact us here.

 

Image credit: Pavlofox and Arcaion

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