[T-rex]

Ty here. This is my first post.
Born in FL, raised in GA, lived in NY 13 yrs, now in IL for 10 yrs. My dad was a Boilermaker but I didn't get to learn any arc welding from him. I've done lots of tiny torch work at a bench (jewelry) so I understood principles regarding heat travel but that's about as far as I got before borrowing and goofing around with a MIG welder. By now I've played around with MIG & TIG and just got my hands on a Lincoln buzz box. I've been in carpentry related trades now for over 20 yrs and have only pursued welding knowledge for the last year. I look forward to learning as much as I can and am glad to have access to this forum and the willing and generous experts who take the time to field questions from the likes of me.

My first question...I've watched most of the weldingtipsandtricks YouTube videos and have picked up some principles here and there...however I just saw a program where a small high end sports car manufacturer TIG welds their mild steel tubular frame with silicone bronze rod, and the narrator made the point that the lower melt temp was desired. My question is why?

[Mike]

Welcome to the forum.

[Otto Nobedder]

Welcome, Ty!

I have not seen the program you described, but if I were to hazard a guess, the silicon-bronze will provide the desired joint strength if the wetted area and fill is the right size, and the lower temperatures will not significantly affect the properties of the high-alloy steel that's being joined.

I've heard of similar procedures for motorcycles and high-end bicycles.

Don't quote me on it, but there's a certain logic behind it that makes sense to me.

Steve S

[Arno]

I have not seen the program you described, but if I were to hazard a guess, the silicon-bronze will provide the desired joint strength if the wetted area and fill is the right size, and the lower temperatures will not significantly affect the properties of the high-alloy steel that's being joined.

Correct.

Visited such a factory here (well.. 'factory' is a big word.. they only make a few cars each year..): http://www.donkervoort.com/en/cars/donkervoort-d8-gto/



The space-frame chassis are all basically 'TIG brazed' and the explanation was indeed as you mention above that the temperatures are kept much lower which stops the parent material in the HAZ going brittle.

The is especially caused by the fact that the frames are made from surpisingly thin-wall tubes and box sections where the structural strenghth comes from the design of the frame (eg. many triangulations and boxed shapes) and not the individual segments. (very different from rollcage tubes which are much, much thicker walled..)

In the past they did weld frames the 'regular' way and found that especially on crashed cars that they saw a lot of (clean) breaks near the welds. Since then they re-designed the chassis and the style of interconnecting joints and switched to a TIG-brazing style setup and now crashed cars show much more bending and crumpling instead of breaking which is what you're aiming for.

Bye, Arno.

[T-rex]

Thanks for the explanation! The program was 'How It's Made, Dream Cars" and the episode features the Ariel Atom. I guess I could have been more specific at the beginning. Thanks again!