The roof of my hot rod was sloppily pieced together not by welding, but with some kind of body filler or brazing material. At first I thought lead, because the body pre-dates bondo. But lead has a melting point around 600 F, half that of aluminum, which half that of steel. No amount of propane or MAP gas would get any of it to melt. I got the steel so hot it started glowing red...but no melting! It has a brassy gold shimmer when cleaned up. What is this stuff? I want to weld these panels to a frame along these edges, so unless its magic welding flux, it needs to go.
Those panels are brazed together. You cannot weld them without trimming the brazed parts off completely. If you weld close enough to the braze to melt the steel and brass together the result is exceptionally brittle.
Shouldn't the brazing melt though? Or am I misunderstanding what brazing is exactly.
Oxy Acetylene, and way more focused than your picture. You won't be able to weld to the steel even if you get the brass off, because it has melted into the steel, and will pop and fizz and piss you off endlessly.
In reply to maschinenbau (I live here) :
I would say it's brass (copper-zinc).
Can I grind it flat and apply bondo over it?
In reply to maschinenbau (I live here) :
Yes
ShawnG
UltimaDork
6/11/20 10:42 p.m.
It's brazing.
The steel is getting red hot because it's thinner than the brazed joint.
Looking more closely at the middle photo I see there is already an intergranular penetration crack growing. That is occuring because the steel was too hot during the braze operation. It sucks, but is not a surprise.
NOHOME
MegaDork
6/12/20 10:38 a.m.
I hate brazed repairs. I run into them on occasion when I am doing tin work for someone and I find previous work done in the 70s or 80's. It means either I am about to eat the time or the owner is going to get a bad call. Seems to have fallen out of vouge after that as the MIG became more popular.
