Alloy frame headtube dent-any material scientists out there?

leighz
leighz Posts: 175
edited February 2009 in Workshop
Bought a bargain frame today - or at least I thought it was a bargain until I saw a tiny dint in the very top of the headtube. It's very slightly deformed the inside but the integrated bearing still goes in okay. The inside surface is not split

Pain is that I know the place I got it from doesn't have another.

Frame is made out of 7005. Will it survive? Or will it split?

Do I take it back or just build it, ride it and see?

Example image:

ywhapb.jpg

More images: http://headtube-dint.fotopic.net/c1648836.html

Comments

  • redddraggon
    redddraggon Posts: 10,862
    I reckon it'd fine, but I ain't graduated from the School of Materials yet.

    If it was new I'd send it back for a replacement if it is possible.
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  • Wappygixer
    Wappygixer Posts: 1,396
    I'd say its fine.
    It doesn't look like a high stress area.All the stresses will go higher up the bearing cup.
    Even if it does crack I'm sure 7000 series alloy can be welded as its not heat treated ( I stand to be corrected on this though)
  • redddraggon
    redddraggon Posts: 10,862
    Wappygixer wrote:
    I'd say its fine.
    It doesn't look like a high stress area.All the stresses will go higher up the bearing cup.
    Even if it does crack I'm sure 7000 series alloy can be welded as its not heat treated ( I stand to be corrected on this though)

    7000 series are normally heat treated. They are welded first and then can be heat treated to lower the damage in the HAZ.

    They are often treated using the T6 method.
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  • LeighB
    LeighB Posts: 326
    Looks ok to me, aluminium alloy is quite resilient so I don’t think it would be a problem. Most stuff that is sold for the road is over engineered to allow for miss treatment. I used to work in a garage and they had a TIG welder and the main mechanic did all sorts of repairs on alloy components that were damaged; I don’t remember having any fail.
  • k-dog
    k-dog Posts: 1,652
    That's a pretty thick part and as others have said won't be under a lot of stress so it will be fine.

    I wouldn't even think about welding it - the heat will transfer and weaken the thinner tubes of the top tube which is a bigger issue.
    I'm left handed, if that matters.
  • nicklouse
    nicklouse Posts: 50,673
    ok the bearing fits, but does it seat properly on the bottom?

    It could be ok.

    if the bearings fit and seat ok then i would not worry.

    I have seen worse dents "sorted" on standard headset fittings.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
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  • Al_38
    Al_38 Posts: 277
    Looks okay to me - if the headset goes in it should be fine. that area is unlikely to be highly loaded in normal use on the bike too
  • on-yer-bike
    on-yer-bike Posts: 2,974
    nice picture
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  • leighz
    leighz Posts: 175
    cool

    I'll just stick it together and ride the thing then

    thanks all
  • maddog 2
    maddog 2 Posts: 8,114
    you could always put a load of dints in it, so it looks like a design feature..
    Facts are meaningless, you can use facts to prove anything that's remotely true! - Homer