Kirkham Motorsports University How To Fix An Aluminum Fender

[David Kirkham]

Originally Posted by Mark IV

davd, The hammer and dolly work does not work harden the alloy?

I saw the panelbeaters at Autokraft in 1985 weld the aluminum using "parent metal" (strips of the alloy) and "sooting" the weld area up. When they changed the flame mix they heated until the soot burned off and just after that point the "rod" would flow into the weld area. of course a little more heat and the whole mess ran onto the floor in a puddle.......

I can see I should have explained this better.

Hammer and dolly work does indeed harden the aluminum (just like most any metal). The term in the industry for this hardening process is "work hardening." Any time you bend, twist, pound, forge, or otherwise move metal, it hardens. Annealing removes the work hardening and returns the metal to a soft state. You can do it over and over again (hence, my reference to rolling ingot into plates and sheets). Each time you roll the plate, you refine the grain structure (like our wonderful 5083 SPF alloy)--but that is a discussion for another day

As to the process you describe, it sounds more like aluminum brazing than welding. If there is any soot at all on a panel before you weld the soot will severely contaminate the weld. I have never had any luck brazing (the joints were not ductile at all). Welding aluminum is very similar to welding anything else--you make a puddle and dip the rod into the puddle to make a joint. The rod doesn't ever "flow" into a joint.

David