Peening Aluminium
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  1. #1
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    Peening Aluminium

    Has anyone ever peened an Aluminium weld to relieve stress?
    I've never heard of it myself , would it achieve anything on Aluminium ?
    My initial impression is no, but I'm open to input from the more knowledgeable here.

    We need to weld up 17 beams out of 200x50 box section (8mm wall) they have 160x 10mm bottom flanges welded to the bottom for the full length and some other assorted fittings .
    They are for some very large external ally louvers .
    A good guess is better than a bad measurement

  2. #2
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    Re: Peening Aluminium

    Never heard of anyone doing it. I used to weld a lot of AL and never had to.
    The difference between art and craft is the quality of the workmanship. I am an artist.

  3. #3
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    Re: Peening Aluminium

    X2

    I've peened connecting rods but never Aluminum..

    ...zap!


    I am not completely insane..
    Some parts are missing

    Professional Driver on a closed course....
    Do not attempt.

  4. #4

    Re: Peening Aluminium

    We shot peen forged pistons (2618).

  5. #5
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    Re: Peening Aluminium

    Quote Originally Posted by Brett View Post
    Has anyone ever peened an Aluminium weld to relieve stress?
    I've never heard of it myself , would it achieve anything on Aluminium ?
    My initial impression is no, but I'm open to input from the more knowledgeable here.

    We need to weld up 17 beams out of 200x50 box section (8mm wall) they have 160x 10mm bottom flanges welded to the bottom for the full length and some other assorted fittings .
    They are for some very large external ally louvers .
    1-pics or a drawing would help the rest of us visualize what you're talking about, mate.

    2-Since you're describing welding a flange along the entire length of the beam, is what you're really asking about is controlling significant distortion of the beam from welding this continuous welding of the flange????

    3-If my guess is correct, then peening won't buy you zip.

    4-planned placement of the welds, relative to the sides of the box beam will help--some; if that's possible, within the design.

    5-the ultimate way to manage this weld-induced distortion, is to pre-stress the beam,
    prior to sequential tacking and welding this flange. Myself and others, here can provide you with at least a general idea of how to do this. Prepare to do some r & d, and make some scrap parts.
    In any case--you will not end up with a dead straight beam. With some effort, you can get it 'close'...but not 'perfect'.

    This needs to be discussed with your customer, prior to beginning the job--defining, in writing what is acceptable and what isn't--with tolerances.
    Blackbird

    Fat Bastard for President-2016

  6. #6

    Re: Peening Aluminium

    When I hear peening of aluminum, all I hear is work hardening which isn't really a good thing.

  7. #7
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    Re: Peening Aluminium

    Quote Originally Posted by dave powelson View Post
    1-pics or a drawing would help the rest of us visualize what you're talking about, mate.

    2-Since you're describing welding a flange along the entire length of the beam, is what you're really asking about is controlling significant distortion of the beam from welding this continuous welding of the flange????

    3-If my guess is correct, then peening won't buy you zip.

    4-planned placement of the welds, relative to the sides of the box beam will help--some; if that's possible, within the design.

    5-the ultimate way to manage this weld-induced distortion, is to pre-stress the beam,
    prior to sequential tacking and welding this flange. Myself and others, here can provide you with at least a general idea of how to do this. Prepare to do some r & d, and make some scrap parts.
    In any case--you will not end up with a dead straight beam. With some effort, you can get it 'close'...but not 'perfect'.

    This needs to be discussed with your customer, prior to beginning the job--defining, in writing what is acceptable and what isn't--with tolerances.

    Sorry Dave I should not of mentioned the beams , it was the beams that first started me thinking of it.
    I have never needed to do it my self as the only steel we use is stainless , and then only thin wall. But I have heard of people talking about peening manually large V butt joints in mild steel to relieve tension across the face of the weld. I would not attempt a structural weld that size as it is out side my experience, training and expertise.
    I was wondering if it was ever done on aluminium.

    Brett
    A good guess is better than a bad measurement

  8. #8
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    colorado
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    Re: Peening Aluminium

    Never peened aluminum but using the wrong alloy aluminum welding rod could crack.

  9. #9
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    Re: Peening Aluminium

    Quote Originally Posted by Brett View Post
    Has anyone ever peened an Aluminium weld to relieve stress?
    I've never heard of it myself , would it achieve anything on Aluminium ?
    My initial impression is no, but I'm open to input from the more knowledgeable here.

    We need to weld up 17 beams out of 200x50 box section (8mm wall) they have 160x 10mm bottom flanges welded to the bottom for the full length and some other assorted fittings .
    They are for some very large external ally louvers .
    Relieve stress? No, the base material is usually too "plastic" durring cooling and it will move rather then create stress.

    However, it can be used to straighten after welding, but it usually isn't done on corner joints for obvious reasons.

    The alloy will determine how the material work hardens.

  10. #10
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    Re: Peening Aluminium

    Quote Originally Posted by makoman1860 View Post
    Relieve stress? No, the base material is usually too "plastic" durring cooling and it will move rather then create stress.

    However, it can be used to straighten after welding, but it usually isn't done on corner joints for obvious reasons.

    The alloy will determine how the material work hardens.
    Cheers makoman
    A good guess is better than a bad measurement

  11. #11
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    Re: Peening Aluminium

    Quote Originally Posted by Brett View Post
    Has anyone ever peened an Aluminium weld to relieve stress?
    No, I usually find a more creative way to relieve stress. 12ga on furry things, explosives, etc...

  12. #12

    Re: Peening Aluminium

    The peening closes microscopic cracks that are in almost all aluminum and other metals. It's the same as if you took a chisel with a mushroomed and split head and hammered all the metal back together and eliminated the gaps- you made it stronger.
    This is why you shot-peen connecting rods. Oh...many shops claim to shot-peen rods and pistons but they are just bead blasting them. To do correct shot-peening, there is a special procedure and special equipment that's necessary.

  13. #13
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    Re: Peening Aluminium

    Quote Originally Posted by turboblown View Post
    The peening closes microscopic cracks that are in almost all aluminum and other metals. It's the same as if you took a chisel with a mushroomed and split head and hammered all the metal back together and eliminated the gaps- you made it stronger.
    This is why you shot-peen connecting rods. Oh...many shops claim to shot-peen rods and pistons but they are just bead blasting them. To do correct shot-peening, there is a special procedure and special equipment that's necessary.

    Ehhhhh sorry your way off in left field with that one.

    Shot peening puts the surface of the part in compression so that as the part is alternately loaded, the tensile loads are carried sub-surface. This increases the fatigue life by not putting the highest stresses on the surface where surface conditions ( corrosion pits, ridges, etc ) can cause stress risers etc. Sorry for the simplification here and not hitting all the details, just wanted to give an "eagle eye" view of it.

  14. #14

    Re: Peening Aluminium

    I guess I was trying too hard to put in in simple tard terms.
    Yes- what you said. That was my description of "closing the gaps" and distributing the load.

  15. #15
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    Re: Peening Aluminium

    Quote Originally Posted by turboblown View Post
    I guess I was trying too hard to put in in simple tard terms.
    Yes- what you said. That was my description of "closing the gaps" and distributing the load.

    Ok good,
    Have to be careful when talking about cracks and such. If there are surface cracks, peening does no good as it just peens them shut, not away.
    We see this frequently in crankshafts where the journal fillets have been "heat checked" durring grinding, inducing micro cracks, then the fillets are shot peened. The crack still exists, and is an initiation point for a fatigue crack. This is also why parts that are shot peened are checked with magnetic particle inspection and not dye penetrant, since the area in tension is actually sub-surface, any cracks that form will form below the surface of the part and may not have breached yet.

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