Ask your WELDING questions here.

Discussion in 'The Garage' started by KTM640Dakar, Mar 5, 2007.

  1. clintnz

    clintnz Trans-Global Chook Chaser

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    I have welded mild steel gussets to my 640's 4130 subframe with no issues. I would have used 4130 for the extra pieces but it wasn't available locally in the size I needed & the extra few % of strength wasn't critical.

    Cheers
    Clint
  2. Strong Bad

    Strong Bad n00balicious

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    4130 will work just fine
  3. KTM640Dakar

    KTM640Dakar Motorsick

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    The 4130 Chromoly steel is a higher tensile strength than 1018 but you can weld them together. Use an ER80S-D2 welding wire like Super Arc LA90 to match the 4130 or use a mild steel ER70S-6 it match the 1018. Either will work.

    :D
  4. griffo1962

    griffo1962 Long timer

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    more a question about post welding treatment....

    my kid has a scooter with a smallish crack in it. it is an expensive deck so I want to try and get it fixed rather than buy a new one. according to interwebs it is made from 6061T6. once it is welded will it need to be heat treated?

    tia

    g
  5. MiteyF

    MiteyF Long timer

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    I just today read a bit about someone repairing a motorcycle swingarm that was 6061. There were differing opinions from "throw it away if you value your life" to "depending on potential stress risers from where the weld is, as compared to the forces on the swinger, it should be OK"

    Perhaps post a picture so the better-informed welders can help?
  6. griffo1962

    griffo1962 Long timer

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    good idea. I'll try and get one soon.
  7. jar944

    jar944 Been here awhile

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    If it was a trail bike, I wouldn't have a issue running that swingarm. O/a heating or not. Lots of welded swingarm extensions that are 12+ inches that have not failed.

    Also Honda uses 7xxx series for their extrusions. Lots of guessing in that welding web thread.
  8. MiteyF

    MiteyF Long timer

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    Lots of guessing on that site in general :lol3 not to say my welding projects don't have their fair share of speculation!
  9. Benesesso

    Benesesso Long timer

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    First question, why did it crack? From vibration/normal riding or a crash? Your as-welded area gives up a lot of strength--nearly half. The weld area will likely crack again, and sooner. You must use filler metal when welding 6061--no autogenous welding for that alloy. Use 4043.
  10. griffo1962

    griffo1962 Long timer

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    I think it was general use and jumping it. It started out approx 10mm and is now about 50mm long. got it 4043 filler.
    Do you have any experience with gas (oa) welding aluminium? lots of youtube videos showing it being done.....
  11. Benesesso

    Benesesso Long timer

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    No. I am much more of a welding engineer than a welder. I've never had the skill for the art of good welding. But there is a lot of science and engineering behind good welds. Yes, OA welding of alum. is fine, but you have to use flux. Many welders think the flux is to take care of impurities in the base metal, but the primary reason is to break down the tough alum. oxide that covers the surface.

    If you do proceed to weld it and manage to do it without weld bead cracking, during riding it is very likely to crack again alongside the weld (the HAZ).
  12. D.T.

    D.T. Difficult but useful

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    We have a compressor at work that started leaking oil. It was from a weld where a foot was welded on for mounting. Coupler went bad and it started vibrating, hence the crack. Tank is 1/2" thick and was full of oil. Curious to see how the person would go about repairing it.

    We called a few people to get it repaired and a R stamp for inspection.
  13. Danjal

    Danjal Insert wit here.

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    From personal experience in commercial applications- welded aluminum will crack again at the weld unless finished and welded correctly. Weld it,then grind off the weld so you don't make a stress point there and call it a day unless his scooter goes pretty fast. The picture will do good in determining stress points.

    At one point in time I started welding perpendicular lines across our fender welds,they'd hold longer,but would eventually fail at a weld again and normally follow the thicker bead of repaired aluminum. Those that I ground back flat had much less of a failure rate. By design the fenders flex going down the road. While I'm not an engineer by trade,I'm assuming the thicker welded area was more rigid andthe added stiffness caused the cracks.
  14. ericrat

    ericrat Long timer

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    I have done a very little bit of gas welding Aluminum with a Henrob torch. the Henrob isn't magic, but the low pressure helps to not blow through the puddle. It works. But, it puts a lot of heat into the piece. This is great for aluminum bodywork, gastanks, stuff that is needs post weld forming as it comes out annealed.

    I would think TIG would put a lot less heat into the piece.

    Eric
  15. griffo1962

    griffo1962 Long timer

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    I have a Henrob as well. Only used it a few times but really like it so far. Going out today to try and find the supplies I need.....
  16. KTM640Dakar

    KTM640Dakar Motorsick

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    6061 T6 is a popular aluminum alloy. You can weld it with 4043 or 5356 filler metal. TIG or MIG weld it. You don't need to heat treat it.
  17. griffo1962

    griffo1962 Long timer

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    thanks :D
  18. griffo1962

    griffo1962 Long timer

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    finally got some time for photos. it's longer than I thought, close to 70mm plus found 2 off shoots as well.

    [​IMG]
  19. KTM640Dakar

    KTM640Dakar Motorsick

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    Grind out so it is shinney and weld it.



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  20. KTM640Dakar

    KTM640Dakar Motorsick

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    What happens is that the heat affected zone near the toes of the weld is the weak link and that is where the crack happens. Also if there is a thick to thin area it will create a stress riser and through fatigue will crack.


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