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Thread: Headpins

  1. #11
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    As is understand it, precipitation hardening is different from work hardening in that it makes metal hard but brittle, so not ideal for thin wires. Dennis.

  2. #12
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    Why cant you harden it in the normal way. I want it for the ends of earwires, just a feature, instead of making a ring, plus I want to make some more studs for me which are just a ball on a wire.

  3. #13
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    Quote Originally Posted by Patstone View Post
    Why cant you harden it in the normal way. I want it for the ends of earwires, just a feature, instead of making a ring, plus I want to make some more studs for me which are just a ball on a wire.
    You can harden it in the normal way. Argentium work hardens just the same as traditional sterling. All I was saying is that you can, if you want, also harden Argentium by a simple heat treatment, which can result in a greater hardness than you can achieve with traditional sterling. (But it's not compulsory.)

  4. #14
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    Oh I see, always worked with sterling, and gold if I can afford to buy it. I will give it a try next time I place an order, thank you.

  5. #15
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    Quote Originally Posted by Dennis View Post
    As is understand it, precipitation hardening is different from work hardening in that it makes metal hard but brittle, so not ideal for thin wires. Dennis.
    Interesting - I've not heard that before. I simply assumed that precipitation hardening and work hardening would result equally in increased brittleness - plasticity decreasing in proportion to hardness increasing. But perhaps there's a difference in the internal structure of the alloy in each case? A superficial Google search doesn't reveal anything much - any suggestions as to where I could find out more about it?


    Going back to the oven/kiln issue - this is part of an answer I got a while back from Peter Johns, the inventor/creator of Argentium. I had several other questions, but was asking here specifically about precipitation hardening:

    a) How critical is the timing and how should it differ for items of different sizes - say, for example, a skinny earwire or a chunky ring? I've read advice ranging from 30 mins to 2 hours...

    We generally recommend 300C for two hours because in our experience most objects, no matter how large or thick, will be hardened in this time. Thin wire should harden in one hour at 300C. It is also possible to use lower temperatures for smaller size objects. At 220C for two hours for example, small objects should harden sufficiently (220C being the maximum temperature in most UK domestic ovens). The hardening times quoted are time at temperature, followed by a slow cool.

    b) Should this always be the last stage before final cleaning and heat-treating for tarnish resistance, or is it OK to carry out some further work on a piece - eg cutting/engraving/polishing - after precipitation hardening?

    Hard metal is generally better and easier for polishing, engraving and machining. We recommend hardening Argentium 960 after the last annealing or soldering operation and before finishing. Stones can be set when Argentium silver is annealed or has been hardened. When hardened Argentium 960 is about the same hardness for setting as fourteen karat gold. Where stones have to be set that are sensitive to heat it is obviously better to harden before setting the stones.

  6. #16
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    Quote Originally Posted by ajda View Post
    Interesting - I've not heard that before. I simply assumed that precipitation hardening and work hardening would result equally in increased brittleness - plasticity decreasing in proportion to hardness increasing. But perhaps there's a difference in the internal structure of the alloy in each case? A superficial Google search doesn't reveal anything much - any suggestions as to where I could find out more about it?
    a) You're correct, but precipitation hardening is more thorough/even than work hardening.
    b) http://www.amazon.co.uk/Introduction.../dp/1408122634 - not Argentium specifically, but a fairly good treatise on the tech side.

    Hard metal is generally better and easier for polishing, engraving and machining. We recommend hardening Argentium 960 after the last annealing or soldering operation and before finishing. Stones can be set when Argentium silver is annealed or has been hardened. When hardened Argentium 960 is about the same hardness for setting as fourteen karat gold. Where stones have to be set that are sensitive to heat it is obviously better to harden before setting the stones.
    "Hard" here is relative. Hardened silver is still not really a patch on hardened tool steel - it is still a very soft metal. Don't have the Brinell figures to hand at the moment.

  7. #17
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    Thanks for the book link, Peter - another one to add to my ever-expanding wishlist... At risk of flogging this one to death, here's a link to a short article explaining precipitation hardening in simple terms - http://argentiumguild.blogspot.co.uk...argentium.html
    Alan

  8. #18
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    My assumption was based on this excerpt from Ganoksin, from which I assumed that while work hardening distorted the internal structure, precipitation hardening left it crystalline.
    Attached Thumbnails Attached Thumbnails Precipitation hardening.jpg  

  9. #19
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    Quote Originally Posted by Patstone View Post
    I dont normally make headpins but when I do mine dont seem to be perfectly round, is there a knack to this or is it just pot luck and filing after.
    A tip I found somewhere works for me with sterling, which is when the ball first forms it will ride up the wire. Remove the heat immediately. Otherwise I will try Argentium too :-)

  10. #20
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    I'm weird. I like the less than perfect pins.

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