Arc Welding 101: Hot rods and MIG

Q: Can gas metal arc welding (GMAW) be used on motorcycles and hot rods?

A: Yes, but it takes a lot more than just running a good bead.

The popularity of cable TV fabrication shows with the likes of Jesse James, the Teutuls, and Boyd Coddington has generated a lot of questions about GMAW. Although you can use it on motorcycle and car bodies and frames, many factors are involved.

GMAW can be easy to teach and learn, but you need to know metallurgy (the science of metals) and how the heat you apply affects the parent metal. The heat-affected zone (HAZ) means just what it says: It’s the area you’re heating up.

Even though GMAW concentrates the heated area, you still need to know how heat will affect the metal you’re working with. Atoms in steel are arranged in crystal patterns, with different steels having different patterns.

The size of the crystals affects how hard, brittle, strong, and ductile a metal is. Preheat, welding, and postweld cooling temperatures can affect the grain (crystal) size adversely, causing defects such as softening or embrittlement.

You do not want to affect metal adversely on something you will be driving down the road!

I’ll leave you with this thought from engineer Leonard Anderson, who said it well when he explained how critical welds are in hot rods and motorcycles:

”Modifying or changing the front end of a vintage automobile is something that better be done right, or death or injury might result. I would say proceed with care, and on the more critical welds, have them done after you are certified, or by a certified welder.”