In welding, not all metals are created equally. Some metals are in fact much more difficult to weld than others. Often times, metals have what is called poor weldability, making them less ideal to work with. Poor weldability is when there are only a limited number of welding processes that can be used on the metal, and the joint must be carefully prepared in order for the process to create a strong weld. It is also important to understand the amount of heat and pressure to apply and the type of equipment needed for a specific metal. Ideally, the welder would be looking for a joint with no cracking which can hold up to the stresses it may encounter.
In this blog, we will take a look at what makes certain metals hard to weld and why.
Metals That Are Hardest to Weld and What Makes Them So Difficult?
WeldersLab has compiled “A Complete Guide” to the easiest and hardest metals to weld. The author notes that four of the most difficult metals to weld are aluminum, cast iron, brass, and stainless steel.
Aluminum. The first impression of aluminum is that since it is pliable and easily manipulated, it should be easy to weld. In reality, it is considered to be the most difficult metal to weld since it is an alloy and therefore mixed with other metals. Some have even called welding with aluminum a “nightmare.”
Because it is such a soft metal, special tools are needed to make a good weld. Welding with aluminum releases aluminum oxide particles into the air. These are toxic and can result in respiratory and lung diseases. A respirator must be worn for all welding processes when welding aluminum.
Cast iron. WeldersLab notes that while cast iron “is strong and sturdy in appearance, it’s actually very brittle when it comes to welding practices.” The metal needs to be heated up prior to welding no matter which welding process you are using. Stick welding works best for welding with cast iron. The metal must be thoroughly cleaned before welding. If the metal is heated or cooled too quickly, cracking is likely to occur later.
Brass. Brass is difficult to weld since it is made from zinc and copper. Each individual metal requires a different welding process. Before beginning the weld, welders must determine the percentage of zinc in the alloy since it has a lower melting point than copper, so if you overheat the brass, the weld will crack. The correct shielding gas must be selected for the copper, so the metal won’t crack as the alloys separate.
Stainless steel. WeldersLab classifies stainless steel welding as “somewhere in the middle of easy and hard.” This is due to the various types of stainless steel. It contains between 11% and 30% of chromium. Welding it is tricky because:
- It retains heat, and if it retains too much heat, it can warp from high temperatures and distort during the cooling process.
- It retains every blemish and scratch mark that is left after the welding process is complete.
- It is not “forgiving” and does not hide mistakes.
- TIG welding is the best process for stainless steel welding and can produce “beautiful welds,” but it is a slow process and requires experienced welders.
Other metals that are often included in a welder’s list of difficult metals are bronze, galvanized steel, copper, and titanium.
The “trick” in welding even those metals classified as difficult to weld is to make certain you understand:
- The metal itself. Is it an alloy? What are its characteristics? Does heat cause the release of toxic fumes?
- The process used. There are many different welding processes. If you understand your metal, what process works best for it, and learn how to do that welding process, you should be able to create the welds you need for our project.
Vern Lewis Welding Supply Will Assist You
At Vern Lewis Welding Supply, we maintain a complete supply of products needed for all types of welding. Our professionals help you choose the proper materials and tools for your welding needs and answer any questions you may have about choosing the right welding process for the type of metal you are working with.
Vern Lewis Welding Supply also offers classes and welding training to help you hone your welding skills. For more information, contact us online, call 602-633-7481, or stop in at one of our eight convenient Arizona locations.
Sources:
- https://sciencestruck.com/welding-basics#:~:text=Aluminum%20Welding,detail%20before%20working%20on%20it.
- https://www.tws.edu/blog/welding/what-does-weldability-mean-in-welding/
- https://welderslab.com/what-is-the-easiest-and-hardest-metals-to-weld
- https://blog.binzel-abicor.com/is-aluminum-welding-toxic
- https://www.twi-global.com/technical-knowledge/faqs/can-you-weld-cast-iron#:~:text=It%20is%20possible%20to%20weld%20cast%20iron%2C%20but%20it%20needs,as%20well%20as%20careful%20cooling.
- https://waterwelders.com/how-to-weld-brass/
- https://americantorchtip.com/blog/the-pros-cons-and-best-ways-of-welding-stainless-steel/
