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someday I'd like to build (or have built) a frame done in steel with silicon bronze, then treat the frame with that black oxide finish, with a minimal satin clear coat for protection. I think that would look freaking awesome. blackened steel, with the gold joints...I saw this done somewhere on the internet, can't remember where, and it looked sweet.
 

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Discussion Starter #22
yeah but it really makes zero sense to do it if you aren't using cast lugs to fit all the tubes into

nowhere near as strong as simple welds and a hell of a lot more work to do

much easier to mess up and end up with something as brittle as glass

recently there was a Vincent/Featherbed special that somebody built

spent what appeared to be tons of money doing it

and SiBr'd the frame

I looked at it and thought....... retarded
 

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Aren't most current old school brit bike chassis builders using SiBr, gas welded frames?

SiBr is not as strong as steel, and softer....not an issue since many frames have been brazed which is even weaker without problems. SiBr doesn't contract nearly as much as steel while cooling so distortion is way less of a problem. The excellent flow and fill characteristics of SiBr make for some very nice joints and on tube welds can spread the stress load over a larger area of tube for a weld that ends up less prone to breakage than a steel weld in some cases.

I once asked an old timer how the other old timers got those beautiful gusseted welds on their frames....he told me the secret was SiBr rod. Like I said, not as strong as steel....but more than strong enough for all but the most critically designed and stressed components.

I've used the stuff extensively for exhaust systems, frame mods, areas of swingarms etc. Done correctly it doesn't heat the parent metal enough to cause any serious problems. I typically use it for hard to weld stuff, or poor fit up pieces, or for cosmetic reasons. For race frame applications I'd still opt for steel in most cases and only use SiBr if I thought the quality of the weld would make up for any lack of strength....ie extremely awkward welds etc.

As for more work....I find SiBr TIG welding to be much easier and less work than steel. The stuff wets so well, and flows so well you can zip right along. On a properly designed frame almost all the loads are in either compression or tension...in which case the strength of SiBr is a moot point and you'll proably tear through the parent metal before breaking the weld. The destructive testing I did in my shop prior to using it for any race bike work showed that you'd tear the walls out of DOM tubing before breaking a SiBr weld.

Just my experience with the stuff.
JohnnyB
 

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Discussion Starter #24
I guess many seem to find it fashionable but following the lead of those who would perpetuate the practices of the dead and stinking old Brit bike industry

well........ having owned, built, ridden, and wrenched more Brit bikes than I can count

Guess I would be the last to agree with the premise of "the Brits did it that way so it must be best"

I'd not waste a second of my time arguing with anyone about it's superiority to good tig welds

there simply isn't any comparison

heck, I've even had a couple of those guys tell me tig welding on a featherbed frame would destroy it

think one said....... oh that tig is just way too hot

now that

is about as asinine and ludicrous as anything I've ever heard


but none-the-less

the aviation industry gave it up for tig

stands to reason they'd still be doing it if they actually had any reason to believe it was better
 

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No one is saying it's BETTER than steel TIG. Just different, strong enough, easy and looks good.

There aren't gobs of cracked and broken brazed or SiBr TIG'd frames piling up, so I guess it will do. I don't build airplanes, and I've never had a race frame crack a SiBr weld, so since it works, I use it.
And no one said Brit bikes are the best...but they aren't particular famous for breaking welds.

And no one is comparing them to good TIG welds... I'm just saying they are good enough, strong enough, and durable enough for race bikes....which I build.
On thin wall (.035-.049) CR or DOM tubing I'll put the strength of my SiBr welds against any TIG steel weld...cause guess what..it will destroy the tube before the weld, so we'd never know which is stronger, so comparison is moot.
I'm not saying it's the ultimate form of welding, I'm just saying it works, and works good.
JohnnyB
 

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Discussion Starter #27
ok it looks kinda cool when done by somebody that has the hand/eye to lay it well

JB........ at one time not too long ago

there were indeed some of those type frames that broke

in no form or fashion am I attacking you at all

I don't disagree that it can be done and done well

one day I hope to meet you and that we can have a brew or coffee while exchanging some crazy stories
 

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This has been a very interesteting conversation. I'm getting my 220v drop today and look forward to jumping into TIG...

Hacksaw: If I understand correctly, you've done some aerospace work on thin--walled 4130. The engineers did not specify a stress relieving treatment after the weld? If not, do the high fequency machines take care of this? I'm new; mind you.

Ariel Atom cars are fabricated out of DOM using TIG. Afterwards, they are nickel-bronze brazed. I always assumed it was for looks.

Have any of you gys welded T-45 or any of the other superlight steel they use in Europe?

--Chris
 

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from what I recall from my strength of materials classes in college, it's the temperature, plus the amount of time at temperature, that changes the grain structure in steel. All that high-strength steel has been specifically treated for very precise amounts of time/temp based on chemical composition to reach the peak strength for that material.

I would think that SiBr joints would have much less affect on heat-treated steel due to the lower temps used. I would also think that TIG welds would have less affect on the surrounding area than Arc or gas welds since you can get very fine control over the weld pool.

However, this is all just theory in my head because I'm not a welder, and just took classes in it, so the likelihood that I'm off-base is very high.

I also assume there's lots of misinformation out there from people who welded without regard to metal composition and heat treatment and got bad results...
 

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Discussion Starter #30
yes and the method is no pre or post heating

70 series plain steel rod will work just fine

some applications use 80 or 90 series rod

DC is used so "frequency" is not a factor

really CM is just as easy to weld properly as black steel and requires zero glamour

however, it is a very good idea to keep bead width close to metal thickness and interpass temps as low as possible


if you want some real fun with a metal similar in strength to 4130

try some 2205 super duplex stainless

autogenous welds kill it and it costs about ten times (probably more) as much as 4130


anyhow, even SiBr welding gets the parent metal hot enough to make it partially molten since it actually nets about 30% pentration

it is actually different from brazing as brazing does not penetrate or make the parent metals molten

brazing, typically done with brass, requires a very tight fit up, best is clearance of no more than 0.002" or so

which is why best results with brazing occur when using cast/machined lugs

with tight fit up, flowed brass joints will net joint tensile strength over 100,000 psi

I forgot the magic number when the joint strength falls right off but I am thinking at 0.004" the tensile strength is no more than 35,000 psi
 

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LOL,I've said it before but the 'Recommended Reading' needs to go away until it can be limited to something newer
 
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