Silicon bronze tig filler questions

[maxyedor]

Started messing with silicon bronze today on a project where strength doesn't matter, but the cool gold colored beads added a lot. Aside from the angle of the torch seeming to matter more than with ER70 filler, it seemed to flow and work great. Now I'm wondering what sort of strength of it is. I'd like to use it on plate-work and and possibly cage work, but other assorted stuff that needs to be welded to other stuff.

Did some searching on PBB and came up empty handed, did some Googling and got no useful info. So what's the no BS answer, strong enough to weld mild with instead of ER70s-o2, or not strong enough?

[Wyoming9]

What brand is it???

They should have all the specs to tell you what the properties are.

Which anyone needs to know before using any filler metal.

The as welded tensile strength is @ 50,000 psi for the Radnor wire . Which is the only book i had within reach.:D

[jasonmt]

Silicon Bronze filler is generally going to be made to meet AWS A5.7 ERCuSi-A/ASME SFA-5.7 ERCuSi-A.

Unlike other classifications such as AWS A5.18/ASME SFA-5.18 (IE ER70S-2), tests for tensile strength and hardness are not included in this specification (AWS A5.7/ASME SFA-5.7). Chemical analysis of the filler metal, or the stock from which it was made, is the only test required for classification of a product under this specification.

Basically the 50 ksi minimum tensile strength figure is with quite a few qualifiers, I would not personally use it for anything other than decorative work as its yield strength is going to be quite low.

It should be noted that the variables in the procedure (current, voltage, and welding speed), variables in shielding medium (the specific gas mixture or the flux), variables in the composition of the base metal and the filler metal influence the results which may be obtained. When these variables are properly controlled, however, the filler metal should give sound welds whose strengths (determined by all-weld-metal tension tests) should meet or exceed the minimums shown in Table A2.

[frontier2k1]

I don't really have much to add here but if you don't find what you're looking for you can check out the AWS forum at AWS.org. There are a lot of guys on there that know their stuff well.

[stainless steal dave]

Started messing with silicon bronze today on a project where strength doesn't matter, but the cool gold colored beads added a lot. Aside from the angle of the torch seeming to matter more than with ER70 filler, it seemed to flow and work great. Now I'm wondering what sort of strength of it is. I'd like to use it on plate-work and and possibly cage work, but other assorted stuff that needs to be welded to other stuff.

Did some searching on PBB and came up empty handed, did some Googling and got no useful info. So what's the no BS answer, strong enough to weld mild with instead of ER70s-o2, or not strong enough?

post # 3 from jasonmt is some excellent info he is da man:smokin:. i have used silicon bronze tig rod to repair cast iron for machinery and pretty good luck with it- i personally would not use it for roll cages or structuall parts where peoples lives are at stake-there are better filler choices avaliable to you for the welding jobs you are intending to do. if i remember correctly the tig silicone bronze filler rod was kinda expensive also.

[jpmassey]

Started messing with silicon bronze today on a project where strength doesn't matter, but the cool gold colored beads added a lot. Aside from the angle of the torch seeming to matter more than with ER70 filler, it seemed to flow and work great. Now I'm wondering what sort of strength of it is. I'd like to use it on plate-work and and possibly cage work, but other assorted stuff that needs to be welded to other stuff.

Did some searching on PBB and came up empty handed, did some Googling and got no useful info. So what's the no BS answer, strong enough to weld mild with instead of ER70s-o2, or not strong enough?


If you are welding steel to steel on a cage, why wouldn't you use ER70s2? Its probably the best all around filler metal for that use....

[sha_ba_do_bang]

If you are welding steel to steel on a cage, why wouldn't you use ER70s2? Its probably the best all around filler metal for that use....

I think he just wants to use it for the 'cool gold color"

[maxyedor]

Basically the 50 ksi minimum tensile strength figure is with quite a few qualifiers, I would not personally use it for anything other than decorative work as its yield strength is going to be quite low.

Thanks for the info, I can never quite figure out what the Ksi and Psi and all that translates to after it's been melted and mixed with the base metal. If I took a real welding class I mite have a clue:homer:

I'll stick with using it on low-stress decorative junk, dashes, GPS mounts sheet-metal.


I think he just wants to use it for the 'cool gold color"

That was the original reason I picked it up, but the reason I asked about it's strength was that I really liked the way it welds. It makes it very easy to manipulate the puddle and on sharp pointy edges of sheet-metal it will still melt and flow at much lower amperage than normal steel filler. Made keeping the sharp pointy edges on the letters I was welding on sharp and pointy very easy.

[roverjohn]

Silicon bronze is used to connect all sorts of very high stress joints like bicycle frames so to say it's weaker is silly. You don't effect the base metal so you are basically "gluing" the tubes together with bronze. You need more of it because the tensile strength is lower which means you end up with a pretty fillet joint when done correctly. The good news is that the low heat required doesn't affect the base metal and the joint shape spreads the load out therefor they should be stronger if done expertly and you might be able to use slightly thinner tubing. The bad news is your filler costs $10/lb so you go broke making pretty "gold" welds.

/so jonesing to try mig brazing

[suprdave737]

I used to have a welding book that had a section showing a formula ford size chassis that a pro welder had brazed together and the book said the braze joints were stronger than the base metal and that the steel tube would tear before the joints failed.

[jasonmt]

Silicon bronze is used to connect all sorts of very high stress joints like bicycle frames so to say it's weaker is silly. You don't effect the base metal so you are basically "gluing" the tubes together with bronze. You need more of it because the tensile strength is lower which means you end up with a pretty fillet joint when done correctly. The good news is that the low heat required doesn't affect the base metal and the joint shape spreads the load out therefor they should be stronger if done expertly and you might be able to use slightly thinner tubing. The bad news is your filler costs $10/lb so you go broke making pretty "gold" welds.

/so jonesing to try mig brazing


The as welded yield strength of Silicon-Bronze is about 1/3 of ER70S-2.
If you are not "affecting" the base metal it is not a sound weld.
Dilution in the fusion zone is going to lead to both interesting mechanical properties and behavior.


I used to have a welding book that had a section showing a formula ford size chassis that a pro welder had brazed together and the book said the braze joints were stronger than the base metal and that the steel tube would tear before the joints failed.

Gas welding with some ER70S-6 could be considered the poor mans tig welder.

[THachiya]

I used "silly bronze" when I welded up my SS exhaust. No "sugaring" on the backside of the welds (due to the lower temps) and no back gassing needed. For non-structural stuff, it's the bomb!

Good luck.

[jpmassey]

to say it's weaker is silly. You don't effect the base metal so you are basically "gluing" the tubes together with bronze.


I don't agree with this...

Since when is brazing stronger than welding?

[roverjohn]

I don't agree with this...

Since when is brazing stronger than welding?

When you use more of it or when the base metal is not weakened by fusion or heat.

If you are affecting the base metal when using silicon bronze you're using too much heat. That's why you'd use it, to avoid the heat.

In our typical applications the cage(base metal) would be affected by rocks so we'd be unlikely to use the lightest tube possible anyway. So in this case it's a mute point in trying to make the strongest joint in the lightest tube.