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  • 1.  Embrittlement in Insulation pins Alloy309

    Posted 05-13-2020 09:18 AM
    Hi all,
    I am looking for a substitute for SS309 anchor pins, to fix ceremic insulation in a combustion chamber.
    Working temperature is approx. 1000 ˚C, temperature pins approx. 800˚C
    The pins have a diameter of 6mm and a length of 300mm. On 50% of the length the pin is flattened by
    cold forming for fixpoint in anchor hole.
    At the cold-formed spot we found creep and embrittlement, the pins break.
    The stresses on the pins are induced by the weight of the ceramic wool, this is a cyclic load due to vibrations.
    Alloy 310, 330, 601 is considered.
    Please advice.

    Leo van Sintmaartensdijk BSc


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  • 2.  RE: Embrittlement in Insulation pins Alloy309

    Posted 05-14-2020 08:28 AM
    Hi Leo

    At 800degC (1470degF) operating temp for your pins, you are in a range where austenitic stainless, such as 309, will form sigma.  That phase will embrittle the metal at room temperature.  To resist sigma formation​, you need a nickel content greater than 35%.  RA330 should be the minimum you would consider, alloy 600 or 601 would work fine as well, although at higher cost

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    Richard Duncan
    Metallurgist, Technical Sales
    Rolled Alloys
    Gibsonia PA
    724 713 1917
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