[Jewelry making - Article 00640] - Re: [Orchid] Quenching in denatured alcohol

[James Binnion]

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>         The main reason for quenching in alcohol is to get a slower
>     cooling rate.  The heat transfer rate is slower in alcohol than in
>     water so the thermal shock to the item being quench isn't as great.
>     I've never delved into it's effect on grain growth. 

    Grain growth occurs on while heating up or while holding the item at
    annealing temperatures. Once you begin to cool, the grain growth
    stops unless the cooling rate is very slow (think furnace cooling)
    if you were not at  the peak temperature long enough. Grain size is
    mostly a temperature issue, once you get an item to a given
    temperature the grains will only grow to a size permitted by that
    temperature. The time that it takes for the grains to reach maximum
    size for that temperature is determined by the physical
    characteristics of the metals and the temperature you are holding it
    at. The higher the temperature the faster the grains will grow and
    the larger they will be. This is why annealing at too high a
    temperature is a problem, the grains get so large that the working
    characteristics of the metal are affected. It loses strength because
    of the large grain boundaries and can crack or fail during forming
    operations. Grains are made smaller only by cold working of the
    metal. 

Jim Binnion

James Binnion Metal Arts
Phone (360) 756-6550
Toll Free (877) 408 7287
Fax (360) 756-2160
http://www.mokume-gane.com
jbin AT mokume-gane.com
Member of the Better Business Bureau

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