In terms of Malleability, which grade of stainless is closest to copper?
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    Default In terms of Malleability, which grade of stainless is closest to copper?

    I'm working of a medical device and am looking for a stainless wire around 20 gauge diameter that will bend and roughly hold its shape similar to copper. I want to minimize memory in the material as much as possible.

    What would be the closest grade of stainless to use?

    gm

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    They are two completely different alloys. Stainless will strain harden to a greater extent, that property is not comparable.

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    Quote Originally Posted by RC Mech View Post
    They are two completely different alloys. Stainless will strain harden to a greater extent, that property is not comparable.
    Thanks for the reply.

    I realize they are completely different alloys. Maybe I should simply ask which grade of stainless is the most malleable?
    gm

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    304 is the usually go to for stamped and drawn stainless products so industry must have a reason.

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    The 3XX stainless work harden so when you bend them it takes more effort to bend them back. You only have a few bites at that apple before the material fails.

    Good luck,
    Matt

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    Quote Originally Posted by Matt_Maguire View Post
    The 3XX stainless work harden so when you bend them it takes more effort to bend them back. You only have a few bites at that apple before the material fails.

    Good luck,
    Matt
    Thanks for the feedback.

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    Aircraft Spruce has stainless safety lock wire in a variety of sizes, and being meant for tight wrapping around screw heads it's a soft temper. Cheap too...

    SAFETY WIRE - STAINLESS STEEL - 1 LB SPOOL from Aircraft Spruce

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    Quote Originally Posted by Milland View Post
    Aircraft Spruce has stainless safety lock wire in a variety of sizes, and being meant for tight wrapping around screw heads it's a soft temper. Cheap too...

    SAFETY WIRE - STAINLESS STEEL - 1 LB SPOOL from Aircraft Spruce
    Wow...at that price, its well worth picking some up to experiment with. Thanks for the link!
    gm

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    There's a constant for materials known as the strain hardening exponent ( Strain hardening exponent - Wikipedia ). There's more discussion at this link: Work hardening - Wikipedia . The larger the exponent, the higher the rate of strain hardening.

    Here's a table of the exponent that I found. Annealed copper is listed as .54, 304 as .45, 410 as .10, 17-4PH as .05.
    strain-hardening-exponent.jpg

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    Biggest issue most common stainless wires going to be in as drawn temper and thats pretty dang springy, annealed stuff is noticeably less, 304 or 316 are both pretty similar though in my experience.

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    I took Milland's advise and ordered a 1# roll of .025 SS annealed wire. Cost me $20 shipped. Will experiment with that and see.

    Another option I thought of is to use silver wire from a jewelry shop. From what I understand, the only metal that is more malleable that silver is gold. Just not sure how its surface will stand up to the autoclave process. This is going on a surgical device.

    gm.

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    Quote Originally Posted by adama View Post
    Biggest issue most common stainless wires going to be in as drawn temper and thats pretty dang springy, annealed stuff is noticeably less, 304 or 316 are both pretty similar though in my experience.
    Safety wire is fully annealed (quenched in the case of 302-304). Basically used just once & tossed for new if re-torque is required. Gets pretty stiff the first time you twist it and seriously stiff buzzing around in an airplane after a few hundred hours.

    Good luck,
    Matt

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    Default Surgical stitch wire is type 316L

    When closing up after open-heart surgery, they put the sternum back together with six stitches through the bone using stainless steel wire. The sternum was sawed in half aling the vertical centerline. The alloy is 316L.

    Corrosion of stainless steel sternal wire after long-term implantation | SpringerLink

    Wire stitches can also be made of pure titanium (permanent) or a titanium alloy (dissolves after six months or so).

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