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Thread: Improving your alloys

  1. #21
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    Waiting for a lunch meeting to start and was throwing things into dogpile.com. I came up with this:

    http://www.siliconsources.com/index.html

    Anybody try getting silicon from them in backyard quantities?
    Angus MacGyver a.k.a Clifford C. Claven, Jr.

  2. #22
    Senior Member HT1's Avatar
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    Quote Originally Posted by Robert View Post
    I usually machine parts of my castings on a lathe or mill. They do not machine well, especially with a carbide tool. HSS seems better. Is there anyway to improve this thru the use of flux or other additives? How is the 6061 barstock I am familiar with different? I seem to get short broken chips instead of continuous. The material also seems more porus. Do I need to de-gas it? If so how? I did not see a thread about this.
    6061 is heat treated, weld it, and it will machhine awful, like you are scraping putty off your shoe unless the tools are SHARP!

  3. #23
    Senior Member machinemaker's Avatar
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    typically when extruding 6061 you can quench it as it exits the die which is enough to get a T6 heat treatment. Part of this is due to the chemical make up of the alloy. If I remember correctly it is the Mg in 6061 that helps this heat treating. I wonder if you did a solution heat treatment on your castings if they would come back to a T6. I know that you can do this with 357 high mg castings and forgings.
    kent
    Kent
    There is beauty, power and excitement in simple old technology!

  4. #24
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    quenching is just part of T6, it will also require an aging process, holding it at an elevated temp 350F+- for 2-5 hours, depending on thickness. But the extrusion/forging process will incorperate this. but it will require an alloy; CU, Si, Mg are common alloy materials in Al

  5. #25
    Did I read somewhere that adding a little copper into an aluminium melt will improve machinability?

    And would there be any trade-off in strength?

  6. #26
    Senior Member machinemaker's Avatar
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    If I remember right copper additions to aluminum typically do a couple of things. First is that it makes a harder alloy, this can be to the point that it can be brittle. It can also cause casting problems. I remember trying to cast a copper alloy for a rolling stock and it would crack and break if it cooled to fast. However, this was casting continuous slabs for rolling. Seemed like there was a large amount of stress on cooling and it was brittle enough to shatter like glass, I think that it was a fairly high copper alloy though. I used to buy an as cast plate for machining that machined beautifully, but it could not be welded, I can't remember it's trade name. But it did machine great. Copper additions can change the melting temps lower than other alloys. Not sure about what that would do for casting and shrinkage. I am not sure that this is much help. you might look for what ever is used in the as cast plate, it used to be a patented alloy and there was not much chemistry published, but maybe the patents are expired or someone else has something similar.
    Kent
    There is beauty, power and excitement in simple old technology!

  7. #27
    I'd be interested to know how much copper you would dissolve into a melt of alu to make it machine up nicely.

    Machined a part out of Duralumin once (think it was duralumin anyway). It was absolutely lovely to machine!

  8. #28
    Senior Member 4cylndrfury's Avatar
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    Thanks for making this a sticky!
    Last edited by 4cylndrfury; 11-03-2011 at 02:31 PM.

  9. #29
    Senior Member 4cylndrfury's Avatar
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    I wanted to post this here (especially since Rocco, GT, and pat-j fixed the HOF thread - Big THANKS guys!!!) so this information is not lost - this is an exerpt from some information sent from Machinemaker to Rasper regarding DIY Silicon Bronze, or "Everdur":

    Both the Mn and Si will go into solution in the copper very easily. I think the hardest thing is melting the copper without having a lot of oxidation. Here is what I have done when alloying starting from the beginning. I first weigh out my charges, since I use the formula of 94% Cu, 4% Si, 1% mn and the commercial formula has 1% "other", I figure the 1% other is already in the copper, so it is more like 95%. I also add a little bit more copper to cover any oxidation. I will charge the crucible with the heaviest copper scrap I have and use charcoal or coal in the charge to keep the oxidation down. I was told that if you have enough extra carbon with the metal it will reduce some of the oxide on your scrap back into copper, so I use a generous dose of charcoal in the pot. Once you get that first charge of copper melted keep adding charcoal as a flux and start adding more scrap until you have your total amount of copper melted. The silicon metal will want to oxidize too so when I have the copper melted I will turn off the burner, skim back the copper then quickly add the silicon metal and stir. I like to force the silicon under the surface by stirring while dumping the silicon into the copper. I have a piece of steel sheet that I bent into a gentle v shape that I can put the silicon metal on and use as a slide to put the silicon right onto the top of the copper then stir. When the copper is hot enough to be liquid it is very chemically aggressive and the silicon will go right into solution. Oh ya I usually have the mn in with the silicon. After adding the Si and Mn I turn the burner on and get things up to pouring temp, I figure the adding cold metal to the pot drops the temp a little low. Once back at temp, Throw some borax on for flux, I skim, take the pot out and pour the molds. The only problem I have ever had is not keeping the furnace atmosphere rich enough and oxidizing the copper too much where it gets lumpy, sort of mushy with oxide.
    I am sure you will do fine, go for it!
    kent



  10. #30
    Whoa I see a new alloy god over here. Very nice and comprehensive guide for newbies like me Cheerio!
    I believe incoloy to be the best alloy in the world!

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