Why not "braze" reinforcements on?, info from the "Welder's Handbook" Options

[SpecialK]

I was re-reading my copy of Welder's Handbook because my practice welds on some scrap were weak as hell when trying to weld 18ga to some 12ga (rosette welds) to beef-up my seatbelt attach points that rusted out. (IMG:style_emoticons/default/headbang.gif) Needed a break (IMG:style_emoticons/default/beer.gif) to do some research and find out what I was doing wrong.

The author, Richard Finch, is big on brazing automotive sheetmetal repairs as opposed to fussion welding (MIG, Arc, etc.), particularly when it involves pre '80 cars that weren't assembled using HSS (High Strength Steel). He says that the high temps involved in fussion welding actually weakens the surrounding metal, where as the lower temps involved in brazing doesn't. You can't braze butt joints like you'd use to attach outer body panels, but the reinforcement kits like Mark's (Engman) inner long stiffener's and Brad's 10ga beasts would actually be much stronger (at the attach points). His example is taking 1" x 5" long strips of .060" mild steel, overlapping the ends by 1" and brazing them together. In a pull-test machine it takes over 3000 lbs. to pull them apart and it's always the base metal that breaks, never the brazed joint. Since lap joints are the preferred joint when brazing, and all of the weld points (holes) on the reinforcements are essentially lap joints, wouldn't it make sense to braze in the stiffeners rather than MIG weld?

Or then there's always the possibility that everyone does braze their stiffeners in, and I'm just assuming they've been MIG'd (IMG:style_emoticons/default/slap.gif)


Kevin

[John Kelly]

"The author, Richard Finch, is big on brazing automotive sheetmetal repairs as opposed to fussion welding (MIG, Arc, etc.),"

Hi Kevin,

He may be big on it, but he is almost alone in his thinking. You won't find serious metal shapers or restoration people using that method. The best reason for brazing is to join disimilar metals. The author probably had a hard time welding the small stuff, and came to a convenient conclusion. Brazing is kind of like glue, it has its uses, but seat belt anchor points, roll bars, body repairs, are not among them. You might get a way with it, but welding is superior in every way. If you share some picture of your welds maybe we can help you figure out what is going on?

John www.ghiaspecialties.com