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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

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