Silver Soldering/Brazing 303 Stainless to Brass

[4156df]

Hi All,

Before I get to involved in a potential project, can someone tell me if 303 stainless steel can be silver soldered/brazed to brass? If so, any recommendations on flux and solder.

Thanks,
Dennis

 

[Blogwitch]

In the UK Dennis, it is dead easy.

Easyflo silver solder, and Tenacity 5 flux. That will do all your silver soldering normally associated with these sorts of builds.

The flux is the crucial part, this one is designed to take the rigours associated with silver soldering stainless steel, but it is great with all other materials as well, so it will join all metals that you can normally silver solder, to each other, with ease.

Where you come from, it seems like pot luck and you have to go with what you can get hold of.

Personally Dennis, I would bite the bullet and get some sent from across the pond.

I can supply you with a few sites to get it from, if that is the way you eventually want to go. Or if you don't want too much, I can send you some in an envelope.


Bogs

 

[Stan]

Harris is the big name in silver solder in the US. On their web site they list dozens of different kinds of flux. I just copied of a couple as an example. I use the white flux for everything I silver solder and it works well as long as the metal is clean before I apply the flux. It is on the shelf at the local welding supply places.


STAY-SILV® Brazing Flux (White)

An all purpose, low temperature flux for use in silver brazing most ferrous and nonferrous metals except aluminum, magnesium and titanium. Stay-Silv® Brazing Flux (White) is an inorganic fluoride type flux molten at 1100ºF and active to a maximum of 1600ºF. Flux residue may be removed with a hot water rinse. Meets Federal Specification OF499C, Type B; AWS Type 3A; AMS 3410F.

Packaging: 4 ounce jars, 24 to the carton; 8 ounce jars, 24 to the carton; 1 pound jars, 12 to the carton; 5 pound jars, 6 to the carton; 7 ounce brush cap dispenser, 24 to the carton; 25 pound pails; 60 pound pails.
SSWF7
SSWF1/4
SSWF1/2
SSWF1
SSWF5
SSWF25
SSWF60 -
-
-
-
-
-
- Stay Silv White Flux - 7 oz. brush cap
Stay Silv White Flux - 1/4# jar
Stay Silv White Flux - 1/2# jar
Stay Silv White Flux - 1# jar
Stay Silv White Flux - 5# jar
Stay Silv White Flux - 25# pail
Stay Silv White Flux - 60# pail


Stay-Silv Brazing Flux (Black)

Formulated for brazing applications where the work is subjected to rapid, localized heating or where longer brazing times are encountered. It is particularly useful in applications where large amounts of refractory oxides may form, such as with stainless steel alloys. The active range is 1100ºF - 1800ºF. Flux residue may be removed with a hot water rinse. Stay-Silv Brazing Flux (Black) conforms to AWS Type FB3C and AMS 3411 specifications.

Packaging: 8 ounce jars, 24 to the carton; 1 pound jars, 12 to the carton; 5 pound jars, 6 to the carton; 30 pound pails, 60 pound pails.
SSBF1/2
SSBF1
SSBF5
SSBF30
SSBF60
-
-
-
-
-
Stay Silv Black Flux - 1/2# jar
Stay Silv Black Flux - 1# jar
Stay Silv Black Flux - 5# jar
Stay Silv Black Flux - 30# pail
Stay Silv Black Flux - 60# pail

 

[Deanofid]

Dennis, the answer to your question is "yes". You can "silver solder" stainless to brass.
Get any BRAZING wire with the spec BAg-7 or BAg-5 and get white paste brazing flux.

This place has it:
http://store.sra-solder.com/section.php/90/1
They also sell the flux. They call it 601 silver brazing paste flux.

If you already have similar, as I think you do, you're set.

Where you come from, it seems like pot luck and you have to go with what you can get hold of.
Bogs

Not at all, John. The problem with "where we come from" is people insist on using the misnomer "silver solder" in place of what it really is; Silver brazing. If you buy soldering flux, you got the wrong stuff. If you buy brazing flux, you're golden. The characteristics regarding the differences between solder wire and brazing wire are very specific and well defined here. If we order the wrong stuff in our ignorance, we get the wrong stuff in the real world.

We just need to call things what they really are, and we will have a lot less trouble with this seeming mystery.

Dean

 

[Jasonb]

Same problem here if you ask for brazing flux/rod you will get the wrong stuff

Brazing here refers to bronze welding as you refer to it.

Jason

 

[GWRdriver]

It appears (and I emphasize appears) that Harris is moving to the term silver brazing rather than silver solder. The picture is of two identical Harris products, the one on the left being newer material than the one on the right.

 

[Deanofid]

That's a new one to me, Harry.
The only place I've seen something marketed as "silver solder" is jewelers wire. I've used Harris products for a long time, as I was in the welding trade for years. Brazing wires of all types usually had a marketing name, which didn't mean much. We bought it by spec, and it was marked as CuXXX brazing alloy, (for braze welding), or for stainless, silver brazing alloy with a BAg # or percentage #.

How old do you reckon that package on the right is?

Dean

 

[Blogwitch]

Dean,

We tend to use three types in the UK.

Soft solder, as in electronics and plumbing.

Hard or silver solder, which we all know what that is for.

Braze, which uses a higher heat, and a brass based rod. This goes into two main types, braze, which is like a hotter and stronger silver solder, used for 'brazing' tips onto tooling, then there is bronze welding, which usually uses oxy/acet or oxy/propane, and is used like gas welding where you use it like a filler rod as in welding.

There are others, that are used for speciality metal joining, jewellery etc, but the above 3 are the most common, and all 3 have their own distinct versions of flux and rod.

The reason I said that it is pot luck, is that every time the US lads get on about silver soldering, they always start spouting on about a mixture of the two lower temp types, and it soon turns into a melee of confusion, with someone saying use this, and another saying use that.

Maybe someone 'in the know' should do a write up about the different types of soldering in the US, and the correct terminology, plus what is generally and easily available, just to clear up the confusion, then it can be referred to when someone asks the question.

If answering someone from the UK, my statement about the tenacity flux and easyflow rod is all that is needed. They are available almost everywhere where model engineering supplies are obtained, and if used in that combination, works perfectly for 99% of jobs. There are other trade names that can be used, but usually when you go to order them, they state 'the same as Easyflo' etc.

But you only have to look at both yours and Stan's suggestions, and you can see where confusion is setting in already, it only needs one more to enter the discussion, suggesting something else, and the poor person who asked the original question doesn't know which way to turn.

I think in the US, the main problem is there is just too much choice (the same basic item going under different trade names or numbers), too much technical info being quoted for the basic layman to understand, and a lot of confusion about the correct naming of processes.

I am not trying to get you to change anything, only attempting to show what an outsider sees when he visits a post like this.

Simplicity and standardisation cures confusion.


John

 

[Deanofid]

You have it exactly right, John. We think we all have different stuff, but really, we are confusing
ourselves over what amount to a bunch of colloquialisms. You say biccy, I say cookie. Some
kind of sweet cooked dough.

In the first part of your post, about the "soft solder, hard solder, and braze", we have exactly the same
thing here.
"Soft solder", which is plumbers type or electronic solder, usually lead and tin, tin and silver, etc.

"Hard solder" or "silver solder", which is simply not solder at all, and that's where the problem comes
in. It's silver brazing alloy. If someone checks out one of the larger UK suppliers, Johnson Matthey,
they will see that none of the high silver content alloys is described as "silver solder" or "hard solder".
They are all described as "silver brazing alloys" including the EasyFlo types. It's the same from
manufacturers here, too.

"Braze", just like you said, and it's the same here.

That temperature thing? That is what differentiates soldering from brazing, (and I mean, what we call
soft soldering from hard soldering). Johnson Matthey has almost the exact same definition as the
industry uses here in the US. The number they give is 450° c, and the number in the US is 840° f.
Same thing.

The flux I mentioned and the ones Stan mentioned are equivalent products from different makers.
The main thing is "silver brazing flux", which is what we both recommended.

I may not have been clear in that post, and didn't mean to say my recommendation was better than
Stan's. It's the same stuff, different brand. Silver brazing flux. Not soldering flux.
Silver brazing flux, whatever brand you buy. Usually, the white kind. The black kind is for brazing ovens
and like that, or where you have to heat something for a long time to get the job done.
Some silver brazing flux comes dry, some in a paste. Get paste.

I've posted about this flux and silver brazing/hard solder thing over and over, John. I don't think I will
convince anyone that calling something by it's proper name will get you what you want. It seems that
most of us in the US are going to call silver brazing "silver soldering", and until we start asking for what
we actually want, like "silver brazing flux" instead of "soldering flux", we are going to keep having
trouble with the products we get.

We do have a lot of different products! We aren't the only ones. Johnson Matthey has 23 different
silver brazing fluxes on one page, a dozen of them called Tenacity!

As you say, simplicity. I know you are right, too. Here's a try;

If you want "silver solder" or "hard solder" in the USA, (not talking about jewelers stuff), order
45% silver brazing alloy, (specification BAg-5), OR
56% silver brazing alloy, (specification BAg-7).
The name brand of the silver alloy doesn't matter at all if you buy it by spec. Those specs are
the same everywhere in the USA.

For flux, order:
Silver brazing flux, (white paste type). Doesn't matter the brand.
Harris has that. SRA has that. Lots of other places, too.

Dean

 

[Stan]

Dean: It is ironic that you mention jewelers, since they use exactly the same stuff that we use on model engines. They do sell it in smaller quantities at higher price but it is the same alloy. They use different terms for the alloy because they will work with three or more alloys on the same workpiece so that each step will be worked at a lower temperature.

I think everyone agrees that every manufacturer having a trade name for a standard product is ridiculous and confusing. It becomes even worse when they refuse to release the specs on their product to the general public. To me it is a moot point whether it is a high temperature solder or a low temperature brazing alloy. Any place where I buy it knows it by either name but there is frequently confusion if Silfos (silver/copper/phosphorus alloy) is also on the shelf and the clerk is less than knowledgeable.

 

[shred]

The major US problem is the marketeers in the quote hardware unquote store selling "Silver bearing Solder", which every newbie thinks is just the stuff, only much cheaper and easier to come by than some random internet web site and waiting ages for it to arrive. It's only got some tiny % silver and is otherwise as useful (or not) as plain old soft solder.

 

[4156df]

John, Dean, Stan & Shred.

Thanks for the detailed responses. I know there’s been a lot of confusion about soldering/brazing and which is which. Dean & Stan are right about one of the sources of confusion when they mention jewelry. Jeweler’s in the US have no idea what brazing alloy is, but are happy to talk all day about “easy”, “medium” and “hard” silver solder.

Anyway, as Dean surmised, I’ve got what I need to do the soldering. My big concern was about the 303 stainless. I know the machinablity of stainless varies greatly depending on the alloy, but didn’t know if there were similar issues with silver brazing different alloys. Sounds like it won’t be an issue.

Dennis

 

[mark p]

as a jeweler first a machinist much further down the list I can tell you.
jewelers silver solder isn't a silver brazing alloy it is usually a sterling alloy (or germanium if thats what your working)
easy med and hard refer to the flow temps
hard has a higher melting point than easy for adding parts in multiple steps without remelting earlier work
it also will NOT bond to stainless (not for me anyway )
if you are working with silver buy jewelers solder if you are working with steel buy a brazing alloy, they are not the same thing

 

[Jasonb]

Not to mention the fact the jewlers stuff cost at least twice as much as the ME stuff mostly due to the higher silver content (upto 74% vs 42% for typical easyflo)

Jason

 

[TroyO]

Wow! I'm not the OP, but for my part thank you very much for the info!

I also had seen/heard the term silver solder and ended up using what was labeled such from the hardware store... turn out it was the wrong stuff! (US here..)

Conversely, had some plumbing to do and went to get some solder because I "only had silver solder" LOL.

Ohh well, live and learn.

To kind of sum up:
Solder/Soft Solder = Low Temp, under 800* F or so, using dissimilar bonding metal (Or Alloy) to join 2 pieces. No mixing of metals.

Braze/Hard Solder = Higher temp, but still using dissimilar bonding metal (Or Alloy) to join two pieces. No mixing of metals.

Weld = Higher temp (Over 1200* F ?), but joining similar metals with a matching bonding element (IE, 2 pieces of steel with steel filler, or 2 pieces of brass with brass filler, etc.) Metal actually is melted and mixed.

What is it when you use say brass filler to join two pieces of steel? Is that still “Brazing” because the metals don’t match? (That’s the term I know it by anyway, LOL.) That would mean the differentiation between brazing and soldering is determined by temp, and the differentiation in brazing and welding is that the metals involved are melted and mixed?

 

[Stan]

mark p: That is very interesting. Can you point us to the spec sheets for the easy, medium and hard silver solder that jewelers use?

 

[Dan Rowe]

Stan,
Here is a typical spec. sheet from a jewlery supply outfit picked at random.
http://www.contenti.com/products/soldering/solders.html

Click on silver solder sheet.
Dan

 

[Stan]

Dan: The link you posted doesn't give the alloy, just the silver content. On another jeweler supply page I found it listed as a silver/copper/zinc alloy which is what I buy to make model engines. I usually buy on ebay by price and aim for a minimum of 40% silver and try to get 56% silver so that puts me right in the middle of the jewelery spec. I have never had occasion to use a very high percentage of silver and that may only be available as a jewelery solder.

 

[Dan Rowe]

Stan,
Guilty of being lazy,
Here is the specs. from "Jewelry Concepts and Technology" a really informative jewelry book.

Solder Ag Cu Zn Melting °F Flow °F
IT 80 16 4 1330 1490
Hard 75 22 3 1365 1450
Medium 70 20 10 1275 1360
Easy 65 20 15 1240 1360

Dan

 

[Deanofid]

Dean: It is ironic that you mention jewelers, since they use exactly the same stuff that we use on model engines. They do sell it in smaller quantities at higher price but it is the same alloy. They use different terms for the alloy because they will work with three or more alloys on the same workpiece so that each step will be worked at a lower temperature.

Hello again, Stan

The jewelers solder I find on the web has different compositions than any of the regular silver brazing
alloys. As far as using three, (or more) alloys on a piece, you can do the same with silver brazing alloys.
Each alloy melts at a different temp. Use the highest melting one first and work down.

I think everyone agrees that every manufacturer having a trade name for a standard product is ridiculous and confusing. It becomes even worse when they refuse to release the specs on their product to the general public.

Most of the makers of silver brazing alloys in the USA have the complete composition of each alloy
they sell on their websites. Of these, five larger makers, Lucas, Uniweld, Harris, Aufhauser, and SRA, only
one of them doesn't show the metal content in their list of products. The one who doesn't, SRA, just
shows the AWS specification, (the BAg-X number), which must comply with AWS for the given spec.
All makers who want to sell to gubment jobs, or to FDA approval must show the AWS number. If it has
the number, it will be the same an ANY other maker who makes that specific number, and it doesn't
matter what silly name they give it.
I.E., one company's BAg-5 (45% silver), it will be the same as any other company's BAg-5.
I can put up links to all those makers if someone would like to see that the makers are all churning
out the same stuff.

If you are not in the USA, the numbers may mean nothing to you, but knowing that all sellers must use
the same classification will help you get the same product over and over from various US suppliers.

I also had seen/heard the term silver solder and ended up using what was labeled such from the hardware store... turn out it was the wrong stuff! (US here..)

Troy, you got silver bearing solder, and that is the correct and proper term for it. It's truly (soft) solder,
which it's name implies. Usually, this stuff is 96% tin and 4% silver. It's good for a lot of things in the
machinists shop. For a soft solder, it's quite strong. Can't be used it HP boilers, though, as it has a
fairly low melting temp of around 450° F.

Your sum up of the processes is pretty close. A couple of additions may help, or not;

Brazing, as in silver brazing: Above 840° F, base metals not melted, joins by capillary action.

Welding: Melts the base metals, (by whatever means) and joins by fusion of those metals, with, or
without using a filler metal. And it's really hot. Hot enough to melt steel, so, over 2600° F, or there
abouts. Common arc welding makes in the neighborhood of 6500°+F at the arc, oxyacet, about
5600° F.

Braze, as in braze welding: Similar to silver brazing, the main difference being that the joint is not
made by capillary action. Braze welding usually uses a filler of copper alloy, like bronze, and it will
not seep into a joint the way silver brazing does. The base metal is not melted, and the filler metal
just sticks to the surface of the joined pieces, much like a fillet of glue. You can fill a wide gap with it,
much like you could with ferrous welding rods.

Dean