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Thread: Making 85-5-5-5 brass

  1. #1
    Senior Member Robert's Avatar
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    Making 85-5-5-5 brass

    I'm planning on making some red brass.



    I have about 1.8 kilo of Cu. I have weighed out about 110 g of Pb (from an xray tube) Sn from eBay, and Zn from the usual source. That ugly chunk top left is mystery brass that I am assuming is about 70/30 Cu/Zn. I will add about a kilo of that for volume and that will dilute my concentrations a little. That will be OK as long as there is no Si in it which I doubt. Some of the Zn will burn out during melting too. There is some solder on the pipe which is probably Sn-Sb? I will be happy if I end up around 85,8,4,4. If I can get all the copper into solution this will look really red. The lead will be at least 3% which will help with machinability.
    Any thoughts from you metallurgists out there?
    It will probably cost me $21 of propane to make $20 of brass....
    Robert

    On second thought: If my mystery brass really is 30% Zn, I should add NO zinc. Combined with the 2 kilos of other metals that would still yield 10%(minus losses as fumes)
    Robert
    Last edited by Robert; 03-19-2017 at 11:31 PM.
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  2. #2
    Senior Member HT1's Avatar
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    from that picture I do not thing your mystery metal has that much zinc. I would guess just from color under 10% zinc. but that is an educated guess from a poor picture ... listen to the other advice you will get here about melting copper... I would avoid the whole issue and try to find red brass rather then make it. what you loose in oxide will be brutal, and you will use more the $20 in propane melting Cu


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  3. #3
    Moderator DavidF's Avatar
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    Im seeing a whole cup full of zinc LOL
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    I vote with HT-1 on using red brass scrap. It's everywhere. Unless of course you are an incurable experimenter. Then go for it. Most plumbing valves and threaded fittings are red brass. (Brass pipe I think is a different alloy than the fittings.) I collect them and keep buckets of them in my foundry. I just make sure I take out the valve seats, which are sometimes silicon bronze.

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  5. #5
    Quote Originally Posted by Robert View Post
    It will probably cost me $21 of propane to make $20 of brass....
    Just curious, Can you count the cost of propane if you poured a project right away? You would be burning propane to melt bought ingots,right?

  6. #6
    Senior Member Robert's Avatar
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    Thanks guys. I'm gonna give it a whirl. That mystery metal might be less Zn than I thought. So much the better. I have made brasses before without too much difficulty. The zinc losses tend to be ridiculous. I am thinking I will use about $10 of propane on this. The plan it to melt the mystery brass first and then dissolve the Cu in that. I will let y'all know!
    No ingots unless I have extra. I am going to pour this in molds for turning shapes. Cylinders and such.

    HT- assuming I am melting the brass first, in what order and when should I add the other metals? Should I add the Pb abd Sn first then try to dissolve the copper? Should I save the Zn for last since it will be oxidizing and fuming off?
    R
    Last edited by Robert; 03-20-2017 at 02:40 AM.
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  7. #7
    Senior Member HT1's Avatar
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    Melt the brass first, you will loose most if not all the zinc in it ... here is why
    zinc boils at 907c
    yellow brass (85Cu, 15 Zn) melts at 940c, so at the point your brass is liquidus you are loosing Zinc,
    Cu melts at 1085c( Which is higher then the top pouring temp I use for yellow brass 1050c
    C83600 Your goal melts at 1009c and pours at 1065-1287c... that top number is damn hot i would never go above 1200c
    Now remember copper transfers heat away very fast, 4 times faster then brass (see) http://www.engineeringtoolbox.com/th...ity-d_429.html
    So you are depending on the Mysterious "dissolving effect" that some on here claim... I suspect that if you where starting with a red brass like C83600 you might see this dissolving effect with less zinc loss because the zinc probably forms a solution with the lead. but this is opinion not fact. the fact is that most brasses are not in solution but are a mixture, and this allows zinc to boil off.

    I would cut the copper into small enough pieces to fit in the crucible bottom, hammer the pipe flat, to decrease the surface area to mass ratio to help with the oxidization you will have to have some Phos-Cu to degass your finished product. you can use a flux to cover your melt, but it will do little good til there is a liquid bath covering all metal. if you have access you could inert the entire hat with argon or nitrogen, but I dont know how feasible that is in a gas furnace, unless you also have a crucible lid... works great in an induction furnace...


    Good read here https://www.copper.org/applications/...pipe_stds.html

    Personally I would not try it from scratch, if you had 10 Lbs of C83600 and wanted to double it by adding Cu, Zn, Sn, Pb that would be much more reasonable as you could get everything under the molten bath


    V/r HT1

  8. #8
    Senior Member Robert's Avatar
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    Poured!



    I started by melting the brass. My furnace was running great and very hot. Melted 1 Kg before I was ready. Then I added the Sn. Then I started adding copper. It melted/dissolved very nicely into the heel. Next was the Pb. I decided to definitely add some Zn at the end. Boy did that make a lot of white smoke. Hard to hold your breath while stirring. Good thing I have a good ventilation system.
    I poured at about 1850 deg F. More later after I try to machine it!



    Robert
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  9. #9
    Senior Member HT1's Avatar
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    Oh, the black wrinkly appearance on the top of your ingots and risers is a good sign you have more Sn then Zn.
    always plunge zinc under the surface. just tie it to a metal rod with heavy Cu wire. no need to stir, and you loose less to the atmosphere


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  10. #10
    Senior Member Robert's Avatar
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    Quote Originally Posted by HT1 View Post
    Oh, the black wrinkly appearance on the top of your ingots and risers is a good sign you have more Sn then Zn.
    always plunge zinc under the surface. just tie it to a metal rod with heavy Cu wire. no need to stir, and you loose less to the atmosphere


    V/r HT1
    Good tip! Thanks.

    More pics!







    I like the color so far.

    R
    "Whether you think that you can, or that you can't, you are usually right."
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