durabar residual stress
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  1. #1
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    Default durabar residual stress

    Say I took a 4x5x4 chunk of durabar, took off 1/2" all the way around to get rid of the skin, and then drilled a 2.75" hole through the face of it, and then cut it on the diagonal across the center of the hole, does anyone have an idea of how much spring I would see, i.e., deformation in the 2.75" diameter?
    I need to make a cylindrical part with maybe .003 to .007 clearance for the remaining part of the hole. Cutting the block first and them measuring is difficult due to subsequent operations on the block.


    Thanks

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    None. Too much mass involved to see any "spring" in the part. I've worked with Durabar for nearly 40 years and have seen very little distortion in cases like this. Probably less than 0.0005". Now, where I've seen more distortion is in larger OD's with 1" to 1-1/2" wall thicknesses. We have the thin rings induction heat treated on the OD's before we split them into segments. The rings will egg shape, but the segments do not show any distortion.

    If you are worried about it, stick it in the oven and do a stress relieve at 1,000 deg. F for about 3-4 hours air cool then split.

    Ken

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    does that have a skin?

    if your making the hole to clamp onto something cut the slit first.

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    As described above, skin is long gone by 1/2" or more. I'll be cutting out just about half of the section, so a bit more than a slit.

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    Quote Originally Posted by 4GSR View Post
    None. Too much mass involved to see any "spring" in the part. I've worked with Durabar for nearly 40 years and have seen very little distortion in cases like this. Probably less than 0.0005". Now, where I've seen more distortion is in larger OD's with 1" to 1-1/2" wall thicknesses. We have the thin rings induction heat treated on the OD's before we split them into segments. The rings will egg shape, but the segments do not show any distortion.

    If you are worried about it, stick it in the oven and do a stress relieve at 1,000 deg. F for about 3-4 hours air cool then split.

    Ken
    I'm with 4GSR, it should be next to nowt, but to be sure stress relieve first, .......or part machine leaving <> 0.1'' all over, leave to take up it's new shape then finish machine, .......which as we haven't seen the drawings, IMO is a call only you can make.
    Last edited by Limy Sami; 08-03-2020 at 02:02 AM. Reason: pyto

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    Dura isn’t really made by any method that builds stress, ok there is a bit, it’s continuous cast, there is shrinkage but it’s fairly stable from my expirence, nice stuff really
    Mark

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