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CA-ON True Phosphor Bronze

Ontario
Type
Metal

carrdo

Super User
Hi All,

Have been doing some research on this recently and here is what I found. I was looking for true phosphor bronze hexagon bar stock in a specific size (1/2" AF, 5/8" AF, 3/4" AF).

Don't even try to find it here in Canada or in the USA or anywhere in North America. It doesn't exist. All there is is leaded bronze and nothing in hexagon. I need to be able to silver solder it. I have never been successful in silver soldering any type of metal containing lead (i.e. mild steel, stainless, brass, bronze). Others will violently disagree but I am talking about having a structurally sound joint which will be stronger than the parent metal. You can get a joint which looks good but it has no structural strength.

True phosphor bronze exists in the UK. There are two well known types Colphos 90 and PB 102. Both of these alloys have similar corrosion resistance.

Colphos 90 contains zinc and lead in addition to copper and tin and is very easy to machine - like brass. Sources vary on its silver soldering properties. I have not tried it but will not use it for what I want. It is available in rounds, square, hexagon, flat, strip etc. Not all suppliers have every type.

PB 102 is a wrought phosphor bronze. It contains no lead or zinc, just copper, tin and a bit of phosphorous. It is excellent for silver soldering and brazing. However it is difficult to machine (20-25% of free machining brass). It is supplied in rounds, square, hexagon, flat, strip, etc. Not all suppliers have every type.

The above can be ordered in very small quantities (sold by the inch or in 6 inch lengths or a foot in length) by a number of model engineering type metal houses. Despite this, it is not going to be cheap to buy and the shipping here is $$$. Some UK suppliers also do not ship here.
 
Don't even try to find it here in Canada or in the USA or anywhere in North America. It doesn't exist. All there is is leaded bronze and nothing in hexagon.
Sounds like you have done the research but I'm quite sure non-leaded bronze can be had in N-Am. But looks like slim pickens for hex bar you are after. What makes it potentially complicated is trade names. Its time consuming to hunt down the composition list corresponding to title but it should be available. This site is clunky to navigate but they show similar alloys with/without lead & 'some' insight as to composition. Just curious what are these particular fittings for?



PB 102 is a wrought phosphor bronze. It contains no lead or zinc, just copper, tin and a bit of phosphorous.
well... maybe a little 🙂
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I'm uncertain what you are making but would it be possible to start with round (or even square) stock and mill it into a hexagon? For a one-off it is likely cheaper and less effort than searching the world for exactly what you want.
 
Hi All,

Peter: Those lead zinc numbers are trace or zero unless you need some special ultra pure lab or scientific metal. Maybe, at today's prices if you want to buy a ton of it they will make a special run but otherwise forget it.

Replenishing my supplies as getting very low on certain larger phosphor bronze hex sizes. Also used for internal smoke box fittings (like my blast pipe which I just made and described here) and bronze bushes and other fittings set directly into a copper boiler. No zinc or lead permitted here - I am very conservative in this regard. May try certain grades of stainless for smokebox internals in the future but I need to silver solder an internal built up smokebox phosphor bronze assembly soon.

Ken: nobody here (I tried) will sell you true non leaded (phosphor) bronze. Don't believe me - just try it. Ask Helmut Heitz.... when he tried also for one of his locomotives. He went all over North America looking and nothing.
 
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It was just a thought that starting with round rather than hex might expand the list of possible suppliers.

What is the shape of the final part? Is it possible to make it without requiring that multiple pieces be silver soldered together?
 
Hi Ken,

The simple answer is no. It requires an internal annular sealed ring which can be machined but not sealed (superheated) steam and boiler pressure tight without silver soldering the parts together.

Hi whydontu,

Lets see what quote I get back from the UK supplier I have been in touch with first. I have spent far too much time and effort on this already. My DOM tube escapade was quite enough. As I have found out and know, there are lots of things on paper but not in reality.
 
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