Brazing brass to mild steel??

I thought this would be easy to find but I've searched here and Google. What, if anything, is OK to braze together brass and mild steel? I figure regular brazing rod would melt at too high a temp. I have some Forney Sil-Flo which works great on copper/brass but the literature states it is not for ferrous metals?
Thanks

Silver solder - aka silver braze works great, melting point at dull red, a good 200+ celcius below braze - brass and damn near as strong if done right. Metals need to be clean, a simple hearth of a few kiln bricks and its pretty easy to do with a good propane torch.

OK?
in what sense?

there is something called galvanic corrosion.
which means that when you put dissimilar metals together, and add water, in pretty much any form, you will see corrosion in the metal that is lower on the galvanic chart.
Galvanic and Corrosion Compatibility Dissimilar Metal Corrosion - Engineers Edge

in mild, indoor environments, steel to brass is ok.
In salt water, the brass will corrode away.

personally, when I need to do this, I tig weld it with a silicon bronze filler rod.
It will stick nicely to the steel. It will wet the brass- although, if its a standard leaded 360 brass, you will get some popping and bubbling, as the zinc and lead will melt out at pretty low temps.
But I have some outdoor work that is in mild weather, where they dont salt the roads, and its far from the ocean, and the silicon bronze filler between brass and mild steel has lasted over a decade.

I'm making a Manifold for a four burner grill. The burners are four pipes and the Manifold will provide the propane to each burner. I thought I'd use some 1" square tube for the Manifold and tap this for 1/4" npt. This is thin wall so not enough material for a good thread contact so the brazing idea came up.
Non critical and no particular corrosiveness.
I guess I need to see what that Forney stuff is made of. I know I have some silver solder as well but I have forgotten the exact alloy. I bought it a while back to solder stainless mesh.
Thanks

Do not use the brazing rods intended for copper plumbing fixtures and other "red metals" with steel. This stuff has phosphorus in it which does no harm to copper alloys and helps out in several ways: lower temperature, higher fluidity, better fluxing. However, the phosphorus will do very bad things to the steel. We're not talking galvanic corrosion; we are talking brittle intermetallic compounds with a strength approaching that of gypsum wallboard. Snap. Crackle. Pop. Failed brazed joint when you look at it sternly. I do not exaggerate this by very much.

Any of the brazing rods with "Phos" or "Fos" in their name are out, when dealing with steel. All the major makers (Harris, Sarus, Lucas-Milhaupt) have about ten such alloys. Many silver braze alloys with as much as 15% Ag still have as much as 5% P. Therefore, "silver solder" is not a reliable indicator of phosphorus-free. When in doubt, consult the manufacturer's technical data (which probably is not on the outside of the retail store package) to see if it's got anything more than a trace (five hundredths of one percent, maybe?) of P.

For steel-on-steel brazing, there are still a bunch of choices. But for brass-on-steel brazing, your choices are limited by the temperature the brass can withstand. Obsolete braze alloys with high proportions of cadmium could be used as they had pretty low melting points, but they have been withdrawn from the market for being too toxic. (Way, way worse than lead.) If you can't do furnace or big-ass-torch brazing because the braze rod melts after the brass part does, you've got to try something a bit different. TIG brazing (to keep the heat focused and avoid bulk melting the brass) with a silicon-bronze TIG rod like ER-CuSi-A usually works. That would probably be a bit of a hybrid process, as you're probably going to get the brass into fusion welding territory.

^ not calling bull shit too your claims, but people have been brazeing up steel structures with phosphur bronze over here for longer than i have been around, yet to see one fail, what may be a issue on high tensile steels is not so relevent for a lot of things just sitting there.

As to tig brazeing you ever tried that? The plasma is well above the vaporisation point of the zinc, realy does not go well in the real world!

Equally theres plenty of cadmium free silver braze options redily and not too expensively avalible over here off the shelf.

adama said:

^ not calling bull shit too your claims, but people have been brazeing up steel structures with phosphur bronze over here for longer than i have been around, yet to see one fail, what may be a issue on high tensile steels is not so relevent for a lot of things just sitting there.

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This isn't a problem like hydrogen embrittlement. It affects hot-rolled mild steels just as much as high-strength or heat-treated steels. When the makers of the brazing rod say "don't use on ferrous metals", they really have a reason for that!

As to tig brazeing you ever tried that? The plasma is well above the vaporisation point of the zinc, realy does not go well in the real world!

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Yeah, it is not a carefree walk in the park. Torch and rod control make a big difference. But you can put most of the heat in the steel, and keep the molten/vapor area of the brass minimized. Popping and porosity are definite hazards.

Equally theres plenty of cadmium free silver braze options redily and not too expensively avalible over here off the shelf.

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We no longer have any braze options with cadmium here, so all silver braze options here are cadmium free. Problem for the brass-to-steel braze scenarios is many of them have 4-6% phosphorus or much higher melting points. My point about the old toxic cadmium brazes is that some of them had low melting points without phosphorus. The last time I looked (been a couple of years, but don't imagine much has changed), you had to get up to 45% or 50% Ag silver brazes, which are quite a bit more expensive than the 5% or 15% Ag brazes.

The Forney site says that the sil-flo is 7% phosphorus so I'm not using it. I decided to just make some bungs for the fittings and braze them to the square tube so I'll have at least 1/2" thread for each fitting. Easiest solution for me.
Thanks