6069 aluminum and welding

Discussion in 'Cycling Equipment' started by the blur, Apr 15, 2004.

  1. the blur

    the blur New Member

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    does uncontrolled heating/melting of this aluminum weaken its "structure"? does aluminum have a structure? can welding weaken a tube if it's deformed a bit?
    why do i ask? i have a new mountian bike frame and there's a bulge near one of the welds. the tube is not thin there, as there is no defect on the inside of the tube. just a 1 cm by 3-4 mm slight bulge on the outside of the tube. the manufacturer will exchange it but i don't want to bother if it's just cosmetic. any opinions? i have pictures if necesary. thanks
     
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  2. Vintage

    Vintage Guest

    Absolutely. Pic's will help but I think you must accept the
    replacement offer!! It gets serious especially on certain
    areas of the frame where the stresses are at the max such as
    the joint between downtube and headtube where many
    manufacturers add gussets at the bottom. In addition, the
    joints on the tubes frames go through not only tensile or
    compressive stresses, but also TORSIONS! The bulge reduces
    the tube strength to withstand torsions. Remember how
    fatique aluminum mat'ls are.

    the blur <[email protected]> wrote in message
    news:<[email protected]>...
    > does uncontrolled heating/melting of this aluminum weaken
    > its "structure"? does aluminum have a structure? can
    > welding weaken a tube if it's deformed a bit? why do i
    > ask? i have a new mountian bike frame and there's a bulge
    > near one of the welds. the tube is not thin there, as
    > there is no defect on the inside of the tube. just a 1 cm
    > by 3-4 mm slight bulge on the outside of the tube. the
    > manufacturer will exchange it but i don't want to bother
    > if it's just cosmetic. any opinions? i have pictures if
    > necesary. thanks
    >
    >
    >
    > --
     
  3. the blur

    the blur New Member

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    it's not really close to the actual weld-it's on the side of the top tube about an inch from the head tube. it's below a gussett weld on top of the top tube. i think its minor-probably cosmetic only. you can feel it and see it if the lighting is right. there's no defect on the inside of the tube(-i can feel through the head tube)
     
  4. Jim Beam

    Jim Beam Guest

    the blur wrote:
    > does uncontrolled heating/melting of this aluminum weaken
    > its "structure"?

    yes

    > does aluminum have a structure?

    yes

    > can welding weaken a tube if it's deformed a bit?

    yes

    > why do i ask? i have a new mountian bike frame and there's
    > a bulge near one of the welds. the tube is not thin there,
    > as there is no defect on the inside of the tube. just a 1
    > cm by 3-4 mm slight bulge on the outside of the tube. the
    > manufacturer will exchange it but i don't want to bother
    > if it's just cosmetic. any opinions? i have pictures if
    > necesary. thanks

    its not cosmetic, it's structural. take advantage of the
    manufacturers generous offer & have it replaced. to
    perform a safe repair requires substantial work, time &
    expensive equipment making it most unlikely to be an
    economic exercise.
     
  5. In article <[email protected]>, jim beam <[email protected]> wrote:
    >the blur wrote:
    >> does uncontrolled heating/melting of this aluminum weaken
    >> its "structure"?
    >
    >yes
    >
    >> does aluminum have a structure?
    >
    >yes
    >
    >> can welding weaken a tube if it's deformed a bit?
    >
    >yes
    >
    >> why do i ask? i have a new mountian bike frame and
    >> there's a bulge near one of the welds. the tube is not
    >> thin there, as there is no defect on the inside of the
    >> tube. just a 1 cm by 3-4 mm slight bulge on the outside
    >> of the tube. the manufacturer will exchange it but i
    >> don't want to bother if it's just cosmetic. any opinions?
    >> i have pictures if necesary. thanks
    >
    >its not cosmetic, it's structural. take advantage of the
    >manufacturers generous offer & have it replaced. to perform
    >a safe repair requires substantial work, time & expensive
    >equipment making it most unlikely to be an economic
    >exercise.

    Just wanted to add my comments. 2 years ago I discovered a
    crach in my Cannondale bike in the right chain-stay. The
    crach was about 3/4 around the tube about 4-5 cm from the
    dropout, and was caused by an accident 5 years before that.

    I got the frame welded by a friend, who works with metals at
    the university in town. I know that the fram will never be
    as strong as before, but it is a lot stronger compared it's
    state when I discovered the crack. After all, I have been
    riding the frame with that crack... and not noticed it.

    I now use the bike as a spare one when training in bad
    weather. The new bike is only used during competition and
    training in good weather.

    --
    Jørn Dahl-Stamnes
    http://spiderman.novit.no/dahls/
     
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