SILICON BRONZE TIG WELDING

[pamike]

I bought some of this silicon bronze tig rod a while back and recently used it for building up a cast iron vise that had been sawed into multiple times. HOLY **** is the stuff hard. I knocked the high spots down on a belt sander and it was a heck of a time. I then took it to work to have a machinist mill the entire vise flat. He said the silicon bronze was that hard it threw blue chips off a solid carbide endmill. Is it normally this hard? What else are you guys using on cast iron? I was thinking of using it to tig braze body panels but I dont want a material that is that hard to sand and smooth.... THOUGHTS??

 

[BigMike782]

My only reaction is that I need to try it because I do not believe it.

 

[RPH]

We used silicon bronze rod on induction coils. The stuff is tough, especially when compared to the copper coil.

 

[gsloan]

I’ve had that exact experience when using it on cast iron. It doesn’t seem to be any problem to shape when I’ve used it on mild steel parts such as a bicycle frame where I wanted smooth radiused fillets.
I was recently gifted some cast iron repair tig welding rod that I have yet to try to restore a blade slot edge in my Roll-in band saw table. I was told it welds and machines well, but the color won’t match the cast iron. I don’t remember the name. Will be watching this thread to see what others say.

 

[pamike]

Funny you mention Roll In Band Saw. This silicon bronze was on the table clamp for that saw. Someone cut and cut and cut into the clamp and it was in pretty bad shape. I used the silicoon bronze to build up the surface.

I wonder if when using it on cast iron the carbon is drawn out of the cast making the filler harder? It really shouldnt since you really arent melting the base metal. I really want to find a filler rod that is easy to drill and machine.

 

[PugetDude]

309 SS

 

[dffay]

Still theoretical here but I wonder if the heat used to melt it from one state to have it freeze again is essentially work hardening it making harder than before.

 

[pamike]

You use 309SS tig rod to repair cast iron? Or stick rod? Explain please....

 

[welder4956]

Still theoretical here but I wonder if the heat used to melt it from one state to have it freeze again is essentially work hardening it making harder than before.

Good thought, but just welding and cooling doesn't produce work hardening. In addition to work hardening, another hardening mechanism in silicon bronze occurs by heating to red hot (as occurs during welding) and slow cooling, which has to be done to keep the cast iron from cracking. During slow cooling the manganese and silicon in the silicon bronze produce manganese silicate precipitates which harden the alloy. If more rapid cooling is used after welding (such as forced air quenching), then hardening will not occur.

 

[zmotorsports]

Yes, Silicon Bronze is quite hard.

If you follow my Projects 2.0 thread there have been several projects I have shown where I used it over the years. It works great for building up broken or damaged teeth on gears but you are correct, it is hard material so when machining I have found light cuts and lube work well. I have also used it on a few occasions for cast iron repair, the last one on my thread was when I repaired a lower radiator casting for a late 30's Farmall F12 tractor that my brother is restoring. It worked well in that application but I also think either 309 SS rod would have worked well or Ni-99. I like the Ni-99 (nickel) rod a lot for cast iron repair but seems to work especially well with some preheat and post heat or at least controlled cooling of the part afterwards.

I generally use the 309 for dissimilar materials more so than cast iron though. Cast iron usually gets either Ni-99 or Silicon Bronze. I've used aluminum bronze a few times as well but if it will be high wear, high heat or high pressure after machining I prefer Silicon Bronze over the Aluminum Bronze.

 

[Firebrick43]

We used ampco bronze for any wear plates as it was extremely abrasion resistant.

And it was nasty to machine. I would rather machine anything else except possibly 316 ss or titanium than the tough bronze alloys.

309 SS

Have you had luck doing this with tig? Decades ago I tried tig welding CI with castolin tig tectic 680 (a rod superior to 309 for joining dissimilar alloys) and every time I melted the CI it instantly contaminated my electrode.

This piece was hot tanked, shot blasted, and put in the heat treat oven for a shift to burn out any oils even though it wasn’t in any place touching oil and still no dice.

If I wasn’t going to flame table and torch weld cast iron with cast iron rod I used tig silicone bronze.

 

[dogdog]

Maybe Ni99 ? they are advertise as made for Cast Iron / Cast steel, Tig or Stick electrodes, maybe not grey cast iron. and machine-able. except the Ni55 or that other lower Ni one...

 

[theoldwizard1]

Check Keith Fenner's YouTube channel. He has done some cast iron repair several years ago and always says what rod he is using. The video I am think of had great tips for cast iron welding (pre-heat, slow cool).

 

[jsaw]

35 years ago I took a welding class. The instructor taught us how to use a carbon stick in the electrode holder and use Everdur silicon bronze to join metal. It was sort of a poor mans Tig.. He told us that it was sometimes used to join galvanized sheet metal because it was cool enough to not melt the galvanized off the metal.

 

[dffay]

Good thought, but just welding and cooling doesn't produce work hardening. In addition to work hardening, another hardening mechanism in silicon bronze occurs by heating to red hot (as occurs during welding) and slow cooling, which has to be done to keep the cast iron from cracking. During slow cooling the manganese and silicon in the silicon bronze produce manganese silicate precipitates which harden the alloy. If more rapid cooling is used after welding (such as forced air quenching), then hardening will not occur.

That seems sensible. Thx. I knew it had to be in the hot/cold cycles.

 

[Crazyjake8493]

I like silicon bronze on steel or for dissimilar metals, but I much prefer aluminum bronze on AC for cast iron.