Brazing or TIG Welding?

By kaffeend Date 09-23-2002 03:29

I am a manufacturer of bicycle frames, typically using Cr-Mo steel tubing. There're a lot of opinions in this industry as to the best method for joining tubes. Unfortunately, none of these opinions are backed up with facts, and that's what brought me here. I'm looking for any facts as to what method of joining affords the longest fatigue life for alloyed steels. Any information could be sent to me directly at kaffeend@hotmail.com and will be greatly appreciated.

By Tim Buyle (**)

Date 09-23-2002 08:31

a couple of remarks regarding your question :

(1) fatigue life depends on the type of joined connection (stiffness, notches, material, forces, loading etc.) : there will be a lot of different connection types with different fatigue life in the same construction ! do you know the type of loading ? what forces ? it is almost impossible to calculate this for a bicycle
(2) welding and brazing are both suitable for this application , but one must always remember : "the best weld is no weld"
(3) i believe it is more important to make a choice based on production facts (shrinkage, easy to fabricate, efficiency, skills, speed, ...) rather than fatigue life (this is more important for airplanes than for bikes)

By TimGary (****)

Date 09-23-2002 13:35

There was a interesting factual case study published in the August 2002 issue of the AWS WELDING JOURNAL titled "The Development of New Silver-Free Brazing Alloys For Steel Tubular Assembly". This study was performed by brazing 15 separate bicycle frames using 3 different filler metals and completeing physical tests.
Check it out.
Tim