# Brazing rods with super high tensile strength



## mchimonas (Dec 19, 2008)

I've been reading and reading and reading and reading. 

In one book (the Welder's handbook), the author references this stuff called Welco 200 Braze which is 56% silver, melts at 1,155F, and has a tensile strength of 85,000 PSI (stronger than chromoly which is 70,000) which is like super strong. I cannot find it online. As far as i can tell, Harris now owns Welco but I cannot find any Welco 200. Anyone know if it still exists?

If it doesn't, has anyone ever used the flux coated nickel silver rods (which, as far as I can tell, don't really have silver in them). They also have a tensile strength of 85,000 PSI. Do they work well for cromoly?


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## Winter Bicycles (Jun 8, 2008)

Whatcha building?

I use plenty of nickle silver, but for most fillet type applications, high nickel brass (CO4 from Gasflux and similar) works great. Both are fine for chromoly. And no, nickle silver doesn't have an appreciable amount of silver. Most has none (unless in the copper part of the alloy).

56n silver is great stuff, but I'm not apt to try and build a fillet with it (well, not a big one). 

What is your application?


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## mchimonas (Dec 19, 2008)

Probably a fillet brazed mountain bike.


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## Winter Bicycles (Jun 8, 2008)

Nickel silver would certainly work, but typical brass (low fuming bronze), gasflux CO4 etc would work just as well, and usually be a bit less expensive. No reason to pay for a high silver content rod for this application (it's less suited, both as a material and in cost).


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## shiggy (Dec 19, 1998)

mchimonas said:


> Probably a fillet brazed mountain bike.


It is much more difficult to fillet braze with "silver."

Brass rod is plenty strong enough for the application.


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## mchimonas (Dec 19, 2008)

The Paterek Manual had alot of good things to say about nickel silver. I was thinking of trying it out just to learn new methods. I was thinking of using a lugged BB shell (silver brazing that). Using Nickel silver for the HT-DT, HT-TT, and ST-TT and brass for everything else (except small braze-ons). 

Incidently, according to Richard Finch (Welder's Handbook), welco 200 braze (56% silver) is (was) used for race car suspensions and airplane rib wings. Sounds almost too good to be true. he also states that some brazed joints can be stronger than the same joint welded. Interesting stuff. (I am enjoying the tips I am receiving and this discussion).

Marc


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