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Post by Garry Coles on Sept 30, 2022 13:05:37 GMT
Hi. Many years ago I obtained two 12 in X 1 in diameter bronze looking round bar. I didn't know what sort of bronze it was, so it was not going to be used on any thing important. I thought it would come in handy for something one day. And today it did. I am machining up some pipe flanges for a globe valve. The bar machines very nicely. Now, when I was cleaning the lathe afterwards I noticed that a magnet that I had close by had some of the bronze on it. On closer inspection I found it to be only very slightly magnetic. Can someone enlighten me as to what this sort of bronze is.
Thanks
Garry
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Post by Jo on Sept 30, 2022 14:07:34 GMT
It's a bronze alloy, possibly manganese bronze or one of the aluminium bronzes. Ali bronze machines easier.
Jo
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jackrae
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Post by jackrae on Sept 30, 2022 14:34:18 GMT
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Post by simplyloco on Sept 30, 2022 16:51:43 GMT
Agreed. No such thing as magnetic bronze as none of its components are ferrous. |
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Post by flyingfox on Oct 1, 2022 7:14:50 GMT
Could have nickel in it?
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Post by John Baguley on Oct 1, 2022 9:26:55 GMT
The aluminium bronzes are slightly magnetic as they can contain up to 6% iron as well as nickel. I've just tested a piece in the workshop and a magnet sticks to it quite happily.
John
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Post by simplyloco on Oct 1, 2022 10:04:47 GMT
I stand corrected as I was only referring to the alloys of copper and tin!
Aluminum Bronze contains approximately 9-14% aluminum and 4% iron while Nickel Aluminum Bronze contains approximately 9-11% aluminum, 4% iron and 5% nickel. That addition of nickel in the latter further improves the corrosion resistance of a material that is already strong in this area.
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uuu
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Post by uuu on Oct 1, 2022 11:05:52 GMT
This has sparked my interest - so I've run a magnet over the bars in my small stash of bronze - and it sticks to two of them. That's a helpful identifier.
Wilf
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jackrae
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Post by jackrae on Oct 1, 2022 11:49:09 GMT
This has sparked my interest - so I've run a magnet over the bars in my small stash of bronze - and it sticks to two of them. That's a helpful identifier. Wilf It doesn't tell you what it is - just what it isn't  |
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uuu
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Post by uuu on Oct 1, 2022 12:32:33 GMT
Yes - what would be more a more useful test is to know if silver solder will stick to it - before I've lovingly crafted some fittings from it.
Wilf
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jo479
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Post by jo479 on Oct 1, 2022 18:31:49 GMT
If you add salt to easyflo flux you can silver solder Ali Bronze, I made some auto drain cocks once and couldn't solder them together, I mentioned it to the chap from C.Alloys and he said add salt so I did and it worked, so I rescued them from the scrap bin.
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Post by springcrocus on Oct 1, 2022 21:12:57 GMT
If you add salt to easyflo flux you can silver solder Ali Bronze, I made some auto drain cocks once and couldn't solder them together, I mentioned it to the chap from C.Alloys and he said add salt so I did and it worked, so I rescued them from the scrap bin. Interesting! I have marked up a couple of pieces of bronze with "will not solder" after previous problems. The stuff machines reasonably well but seems to hate silver-solder. Time for an experiment, methinks. Regards, Steve |
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Post by chris vine on Oct 1, 2022 23:18:51 GMT
I was given some "bronze" once. I made a complex part from it and could not silver solder it.
Whatever I did leaked. It was porous through the parent metal.
Eventually the penny dropped. It was leaded bronze. Good for bearings. but the lead burns out when you silver solder it and you get a porous mess...
Chris.
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Post by 92220 on Oct 2, 2022 8:18:46 GMT
If you add salt to easyflo flux you can silver solder Ali Bronze, I made some auto drain cocks once and couldn't solder them together, I mentioned it to the chap from C.Alloys and he said add salt so I did and it worked, so I rescued them from the scrap bin. Now that sounds interesting (!!), but how much salt? Is it a small proportion or a large proportion? I'd like to know so that I can try it without too much wastage. Getting it wrong could be a bit dodgy! Bob. |
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Post by nick952 on Oct 2, 2022 9:07:30 GMT
From the Cup Alloys Site:-
Hint 3
Brazing Aluminium Bronze with up to 10% aluminium? Add 20% by weight of table salt to the flux powder. The increase in chloride ions helps to remove the aluminium oxide.
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Post by ettingtonliam on Oct 2, 2022 9:39:34 GMT
I was given some "bronze" once. I made a complex part from it and could not silver solder it. Whatever I did leaked. It was porous through the parent metal. Eventually the penny dropped. It was leaded bronze. Good for bearings. but the lead burns out when you silver solder it and you get a porous mess... Chris. I was once told that silver soldering leaded bronze will be OK provided you don't overheat it, and don't keep it at soldering temperature for very long. I think that means that a quick heat on a fitting would be OK, but leaded bronze bushes in a boiler where its probably going to be at soldering temperatute for an extended period would not be advisable. |
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abby
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Post by abby on Oct 4, 2022 12:49:08 GMT
Interesting thread , and aluminium bronze is definitely magnetic , along with several other non-ferrous materials , including oxygen. As already stated it is a bitch to silver solder and from personal experience it is equally difficult to cast.
An aluminium oxide tube forms around the stream of molten metal as it pours from crucible to mould.
Leaded bronzes contain varying amounts of lead upto 20%.
During years of involvement with casting bronze sculptures, I became very attracted to antique japanese bronze sculpture , especially because of the deep patinas they obtained.
Researching a particular bronze I was suprised to find that it was 25% lead.
I made an ingot of this alloy by melting the copper and adding the weighed amount of lead, mixing and pouring into an ingot mould.
As the alloy cooled and set silver globules of molten lead sweated out all over.
After cooling the ingot and sweated lead was re-melted and cast again three times before all the lead became alloyed.
Sorry if that was boring but just shows how difficult it is to make some alloys.
Dan.
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Post by chris vine on Oct 4, 2022 14:53:11 GMT
Not boring, but fascinating!
My piece of leaded bronze which I had used to make a blast nozzle with gallery and holes for four blower nozzles, was several pinholes when I had silver soldered it. Reheating to seal them made more holes. On the third reheat it was simply porous and I gave up. Machined from another piece of bronze!!
Chris.
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