If you’re new to welding, two beginner-friendly processes you’ll likely hear about are MIG welding and Flux-Core MIG welding. We started with Flux-Core MIG welding. 

 Flux-Core MIG Welding (FCAW) 

In flux-core welding, the wire has a special flux core. This flux generates its own shielding gas as it burns, so you don’t need an external gas cylinder. Some machines can switch between regular MIG and flux-core welding, making them versatile.
I found it extremely difficult. I destroyed about 10 sheets of scrap steel and was really doubting myself. 

MIG Welding with Gas 

Then we switched to MIG. MIG requires a shielding gas like argon. The machine feeds a spool of wire through a gun. This wire acts as both the electrode (to create the weld) and the filler material (to join the pieces of metal). The process also uses an external shielding gas, like argon or a mix of argon and CO2, to protect the molten weld from contamination by the air.

When I pulled the trigger on the MIG gun and felt that argon gas shielding the welding wire, it was so smooth. It clicked, and I realized, “I can do this.”
I love understanding how things work, so I dove into learning everything I could. I read instructions, software release notes, and more. At my job, I’m one of the in-house software experts for our product. A co-worker even said I was the first person they’d seen print out every KBA. I had zero knowledge of metallurgy or welding, but I decided to learn what was really happening.

The Science 

When the MIG welder’s trigger is pulled, something remarkable happens. An electric arc—comparable to a miniature lightning bolt—forms between the welding gun and metal surface, generating temperatures around 6,500°F. This extreme heat transforms metal at the atomic level. 

The arc melts both the welding wire’s tip and the base metal’s edges. As metals liquefy, their atoms break free from their structured arrangement, creating a molten pool where different metals can blend seamlessly. 

A critical part of this process is the shielding gas—typically a mix of argon and CO2. This invisible barrier prevents oxygen and nitrogen from contaminating the weld, which could compromise the metal’s structural integrity. Without this protection, welded metals would become brittle and weak.
As the molten metal cools, atoms realign into a stable crystalline structure. The result? A fusion so complete that the weld becomes stronger than the original materials—a testament to metallurgy’s subtle yet powerful science. 

 I was suspicious of the gas, and one day my argon tank was empty. The MIG gun started to create spatter, and the welds looked like a Brillo pad. It made me think of baking. If you’re missing yeast or an egg, the process won’t work. When you’re welding, you’re working on the atomic level. 

 At the atomic level, the intense heat from the welding arc causes the atoms in the base metal and filler wire to vibrate and break free from their solid structures, creating a liquid pool of metal. As the molten pool cools, the atoms realign into a stable crystalline structure, forming a strong, bonded connection between the materials.