For those familiar with the world of welding, the sensation of metal melting before the touch of your nozzle or the fire of your arc is a familiar yet still satisfying one. For those new to MIG welding, it can be a freshly addictive experience. There’s just nothing quite like the feeling of having that much raw creative power at your fingertips – and nothing so satisfying as seeing sheets of solid metal melt before your very eyes.
But what about the metal itself? What kinds of metal can you melt with a welder, and how do you get it to melt in the first place? There isn’t one answer to these questions, as different metals have different melting points and properties and, thus, require a different approach when welding them.
The following metals can be MIG welded: carbon steel, stainless steel, aluminum, magnesium, copper, nickel, silicon bronze.
With that in mind, let’s take a closer look at which metals can be welded, what it takes to weld them, and a few tips and tricks to help you master metal welding.
Welding with Aluminum
This is one of the easiest metals to weld as long as you have the right tools. MIG welding can handle aluminum easier than TIG welding, though either can work. There are varying grades of aluminum, ranging from the 1000s to 6000s concerning purity and other defining features, so you’ll want to make sure you are choosing the right grade of aluminum for your needs.
1000s level aluminum tends to be very weldable, 6000s level aluminum can be welded, but typically requires extra effort and filler material, and 2000s level aluminum is far less weldable and is typically not the first choice for welding aluminum.
You may also want to consider welding with an aluminum alloy. These are often stronger than aluminum is on its own. That said, the mixture of metals means you have to be careful to heat them at a very specific temperature to make sure that the metals all melt in the right way so as to increase the strength of the finished product once it cools and hardens.
Welding with Low Carbon Mild Steel
Whether you are just beginning to learn how to weld or have been doing so for some time, chances are good that you’ll be welding with low carbon mild steel. It is one of the most common, affordable, and accessible welding materials, and has held that status for a long time.
There are many reasons why low carbon mild steel is so popular for welding, not the least of which being that it has many different applications.
Among the many uses of low carbon mild steel are:
- Steel frames for buildings, as low carbon steel is strong and meets seismic as well as wind requirements, and is likewise mostly impervious to rot, fire, and insects.
- Gating and fencing for the outside of buildings.
- Machinery such as car bodies and other materials that need to be pressed into specific shapes without the risk of breaking.
- Cutlery, with low carbon steel knives able to hold a sharpened edge for a long period of use, and is more nonstick than many stainless steel alternatives
- Pipelines, with galvanized pipes being firm, but flexible, and thus capable of holding a great amount of water and sustaining a great deal of pressure without breaking.
Given that wide range of usage, it should come as no surprise that low carbon mild steel has historically been quite widely used by everyone from scientists to construction workers to engineers. As indicated by the inclusion of galvanized pipes above, this type of steel does a good job of preventing brittleness and porous microstructures which, as described below, can pose a major hazard to your metal. With low carbon mild steel, you typically don’t have to worry about issues such as hydrogen cracking.
Welding with Stainless Steel
Given the amount of things that are manufactured from stainless steel, it should come as no surprise that it is among the most common welding materials out there. Chances are good that the knives, forks, and spoons in your kitchen cabinets are stainless steel (though as alluded to above, in some ways low carbon mild steel cutlery may be a better option).
Stainless steel requires more insight, training, and technique than its low carbon counterpart. That said, they also have a great deal of corrosion resistance, which is good if you are welding something that needs to stand up to corrosive chemicals or moisture. There are three main types of stainless steel – austenitic, ferritic, and martensitic. The former two are very weldable and commonly used, while the latter is more rarely used due to its difficulty, greater hardness, and increased potential for cracking.
Nickel and Copper
Of all the metals on this list, we have been welding with copper for the longest – since at least 3,500 BC!
Copper is softer than either stainless or low carbon steel, and can be quite ductile as well. It does not change when exposed to heat the same way steel does. It conducts a lot of heat, so even at medium thicknesses, you’ll need to preheat your welder to successfully weld joints. In addition, the potential coefficient of thermal expansion is comparatively high, which can cause distortion if you aren’t careful. For these reasons, copper today is typically used as parts of alloys with elements such as lead and selenium.
What’s more, due to its ease of welding and inexpensive nature, copper is often a popular choice for metal sculpture art.
Nickel is likewise often used in alloys. Among the most important tips for welding nickel are:
- Don’t use higher heat settings or amperages as you would with stainless steel
- Nickel alloys tend not to be thermally conductive so the heat builds up faster
- When TIG welding, it is advisable to use a gas lens for the purposes of gas shielding
- Clean the nickel surface between welding passes
- Use argon as your welding shielding gas for best results
- Quick cooling isn’t usually an option so be patient
This is one of the most difficult metals to work with. If you are a beginner to welding, you’ll likely want to try one of the others first. However, if you are up to the challenge, welding with cast iron can produce incredibly strong products.
There are three main types of cast iron, gray iron, white iron, and ductile iron. Of these, gray can be welded with difficulty and white is almost unworkable, while ductile is rarer and a slow process. Between these choices, unless you’re a specialist working on a very specialized job, chances are good you’ll be working with gray iron.
Assuming you have that, you’ll want to choose between MIG and TIG welding. Of these, the latter is better, as the former can splatter more and may not be able to handle the difficulty of the welding process as much as TIG can in this case. It is also possible to weld gray iron with an oxyacetylene torch. While this method is less popular overall today, it can actually be one of the best ways to deal with gray iron given the fact that it is easier to maintain temperature levels.
What to Watch Out for When Welding These Metals
One of the biggest rookie mistakes new welders make is thinking they can meld any metal any way without having to worry about breakage. It can be tempting to think that with that much power in your hands, the metal is simply yours to command. However, that’s simply not the case, and if you don’t take care of the metal properly, it can degrade, as can the quality of your weld.
For starters, with many materials – and steel in particular – you need to make sure that the metal doesn’t become porous. This occurs when pockets of gas are allowed to become trapped within the metal while you’re welding it. These gas bubbles can weaken the metal as well as contaminate the surface, degrading the quality of your weld inside and out.
Related reading: How to Cut Metal with a Welder in 8 Steps
When working with any of these metals, and especially with cast iron, you will need to consider preheating and cooling procedures. The former is important for priming the material so it doesn’t go from a cooler temperature to an extremely hot one in a flash. The latter is vital for the same reason. The time either will take can vary from a few hours to a few days.
Finally, you will want to make sure that the surfaces of any metal you are working with remains clean throughout the weld. Failure to do so can result in pollutants and air bubbles getting in and causing some of the cracking and corrosion alluded to above.
Related reading: 11 Common Welding Defects and How to Prevent Them
There are many different metals from which to choose when it comes to welding. This is one of the things that makes it such an exciting enterprise, as different metals have different natures and are good for different projects. Choosing among different metals is like Picasso choosing among his paints – the right choice can help make a masterpiece.
MIG Welding Thin Sheet Metal >> Check out the video below