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GMAW is a process where you take a wire-fed semi-automatic machine and use it for welding steels. Now, like always, understanding the letters is very important in how the GMAW process works. So the gas in GMAW is very important. In the past, only inert gases were good for welding, but as technology advanced, we were able to put different elements into the wire. That changed everything. Now, we could add small amounts of oxygen to the gas to increase heat. Just like a campfire, you blow on a campfire to increase the heat. Well, now we know, small amounts of oxygen in the weld can also increase the heat of the weld, allowing you to do different things. Now, you don't want too much, because you'll get porosity. So by adding small amounts of deoxidizers in the weld wire, you're able to contradict the oxygen that comes in. So not all GMAW is inert. There are active gases like oxygen and CO2.

When working with metals with GMAW, you want to make sure that you match the metal with the gas properly. When you're adding a little bit of active gases to the gas, you want to make sure that you have those deoxidizers in the wire. Now, by matching them properly, you open it up to a whole another group of welds, whether it's different wires, different hardnesses, different materials, or different positions, you're able to do it in a whole new area, but you have to make sure that you match the wire with the gas properly.

The arc in GMAW is also very versatile. You're able to do DCEP, electrode positive, DCEN, electric negative, or AC which is alternating current. Most welds will require you to be in one or the other area, but with GMAW, you can actually move back and forth between the three different types of electricity. Now, the reason you can do this is that depending on the thickness of the material, the conductivity of the metal, or the hardness of the material, you may want more heat at the plate, which would be electro-positive, and more heat at the wire, which is electro-negative. Or you may want to alternate back and forth with the AC. That eliminates arc blow or any type of spatter.

The welding portion of GMAW is interesting because there's always a filler material. So you will always have a wire being added to the weld puddle. Knowing this, you need to adjust your parameters for welding. Whether it's a groove, a lap joint, or a corner joint, you have to make sure that there's space for the wire that's coming in. You need to have enough heat to melt both the parent metal and the wire sufficiently to create a new weld.