Page 1 of 2 12 LastLast
Results 1 to 20 of 24

Thread: Cracking welds...............

  1. #1
    Guest ross@rmrrestorations's Avatar
    Join Date
    Jun 2003
    Posts
    4,668

    Cracking welds...............

    ....not in a good way.
    The guy I sold my roadster to just sent me this pic. It's from a moby so poor quality but you should see the issue.






    Apparently all 6 or 8 welds where the tubing goes through the boxing plates have cracked. At this point I should say that this is a Mr Roadster centre section that came pre welded with lovely looking machine welds.
    The car has sat in Garrys garage whilst he was overseas. It has the weight of a motor etc sitting on it, but this seems to be a tension type issue.
    All my other cross members, front end and rear shocks, are fine.

    Anyone seen or heard of this before???
    Last edited by ross@rmrrestorations; 08-12-11 at 12:47 PM. Reason: second pic added

  2. #2
    NSRA member
    Join Date
    Jun 2003
    Posts
    4,657
    Images
    2
    very odd.

    There doesn't look to be an awful lot of material in the joint but the pattern would seem to indicate any either.

    The shadow on the boxing plate seems to indicate there is significant undercut but there's so much material in that style of crossmember it surely shouldn't be an issue. But all of the welds appear to have cracked open? Wow .

    More and better pics might help.

    Chris
    Bumper sticker - This is an historic vehicle and only has three speeds....... if you don't like this one you sure as hell won't like the others.

  3. #3
    Guest ross@rmrrestorations's Avatar
    Join Date
    Jun 2003
    Posts
    4,668
    Chris, I,m trying to get better pics just now and also look out some of my pics of when it was naked in the steel.
    I,m a hundred percent sure the tubes go all the way through the boxing plates and are welded on one side only.
    I,m trying to fathom out how every join could have effectively been pulled apart by just sitting parked up??

  4. #4
    NSRA member malstbird's Avatar
    Join Date
    Jan 2008
    Posts
    939
    There is a possibility that there are some residual stresses in the welds themself

    The only possible thing I can think of at the moment is that some external thermal changes have occured - the coeeficient of linear expansion for steel is approximately 4/10th thou per inch per degrees C - if there has been large changes in the temperature where the chassis is stored then it is feasible that along with the residual stresses then contractions of the K member has caused the weld to fail

    It does look like it has failed in tension

    Is the crack all the way through the weld ??

    Mal
    I was told hotrodding was expensive, I laughed.......but it wasnt for long

  5. #5
    Guest ross@rmrrestorations's Avatar
    Join Date
    Jun 2003
    Posts
    4,668

  6. #6
    Moderator jsf55's Avatar
    Join Date
    Sep 2003
    Posts
    14,970
    Images
    59
    Quote Originally Posted by malstbird View Post
    There is a possibility that there are some residual stresses in the welds themself

    The only possible thing I can think of at the moment is that some external thermal changes have occured - the coeeficient of linear expansion for steel is approximately 4/10th thou per inch per degrees C - if there has been large changes in the temperature where the chassis is stored then it is feasible that along with the residual stresses then contractions of the K member has caused the weld to fail

    It does look like it has failed in tension

    Is the crack all the way through the weld ??

    Mal
    I weld .... but i'm no welder ! that bead doesn't seem to be "thick" enough as if the power was set too high ?
    something i was told about called tension weld cracking springs too mind ?
    http://books.google.co.uk/books?id=F...0steel&f=false

  7. #7
    Guest ross@rmrrestorations's Avatar
    Join Date
    Jun 2003
    Posts
    4,668
    Just spoke to him again. Whilst he was in Afghanistan it sat in his garage at home which is unheated. It has been in his heated military workshop for a few weeks now, but I can't see that variance being enough to do this. I think the tube to box plate welds have been done by a different welder to the ones joining all the tubes together.
    They look to have alot more filler added.
    Before it was all painted it was in my workshop for ages and it'a baltic! I would have thought it may have shown up before now?

    Bottom line is it all needs pulled apart an re-welded.
    Last edited by ross@rmrrestorations; 08-12-11 at 02:19 PM.

  8. #8
    NSRA member
    Join Date
    Feb 2009
    Posts
    1,568

    welding

    I could post this up on the Mig Welding forum for any one to comment on if you wish,

    Scarey to see the results of whatever caused the failures, just nice to know there was no serious injury as a result.

    Stan

  9. #9
    NSRA member langysrodshop's Avatar
    Join Date
    Jun 2003
    Posts
    28,748
    Images
    53
    How odd is that Ross !!!
    Any advice or help given is actually based on having done the job, not read about doing it or Googling it.

    www.langysrodshop.co.uk Our parts are air freighted so 5-7 day delivery, The best GRP Willys body available/Rebel Wirings only UK dealer/Speedway Motors authorised dealer/Summit racing/Jegs/Hotrod parts supplied, MAC Autos, We deal with all the US hotrod suppliers even non car related stuff.
    Brake,Oil & Fuel etc plumbing stockist/Totally Stainless fastener dealer/Dolphin Instrument dealer, LMC & Brothers Trucks,
    Stainless Exhaust tube & mandrel bends stockist

  10. #10
    NSRA member Blackpopracing's Avatar
    Join Date
    Nov 2007
    Posts
    4,499
    Images
    1
    I assume it is definitely the weld Ross?

    Without proper inspection, could it be just the paint has shrunk back???

  11. #11
    Guest ross@rmrrestorations's Avatar
    Join Date
    Jun 2003
    Posts
    4,668
    Luckily, the guy is a mate and even though he is pi55ed off at having to strip it all down again, imagine if he had finished it and taken it for an mot to be told the frame was cracked!
    I said I would reweld everything foc but he isn't really local anymore.

  12. #12
    Guest ross@rmrrestorations's Avatar
    Join Date
    Jun 2003
    Posts
    4,668
    Quote Originally Posted by Blackpopracing View Post
    I assume it is definitely the weld Ross?

    Without proper inspection, could it be just the paint has shrunk back???
    Mark, when he first called me that's exactly what I suggested. Some of the other welds I smoothed over and thought maybe the filler had cracked, but it is every tube full circle.

  13. #13
    NSRA member Blackpopracing's Avatar
    Join Date
    Nov 2007
    Posts
    4,499
    Images
    1
    Very strange then?

    Could it be the wrong welding rod/wire?? dissimilar metals etc?? causing shrinkage??

  14. #14
    NSRA member 59zody's Avatar
    Join Date
    Mar 2004
    Posts
    363
    Images
    2
    Ross
    Without knowing what the base materials welded are (not what they are claimed to be) and what the filler metal chosen was (to determine tensile and yield strength overmatch), its difficult to distinguish root cause.
    The paint has to be removed to determine the extent of cracking, but regardless there is a definite issue that needs taken out and rectified, merely welding over again leaves the problem there for a matter of days, months or years, who knows its latent and will reappear.

    Centre line weld cracks are either down to residual stresses or wrong match of filler wire, or inadequate reinforcement. Some of the welds look like they were not very generous with the amount of filler wire put in (also undercut at the base materials tell this). Bunch together the lack of weld, wrong filler material and something forced into the jig for welding and after some time you get what you see in the photos.

    If the weld was to crack due to fatigue (fluctuating loads), the failure area would be at the the toe of the weld to base metal area (called Heat Affected Zone or HAZ). This is where hardness is usually highest and the toughness lowest (brittle).
    The temperature differential you explain by the storage conditionsshould make no major difference, I dont think the chassis was subject to -40degC to +50 degrC swing in a short time for thermal expansion restrictions to play its part.
    For a weld or base metal to crack, it means something has to change dynamically to instigate the failure path. If nothing has changed ,then its down to wrong filler wire and possible poor weld quality (buried defects).

    I would notify the manufacturer and check through the grapevine if this has been heard of before, it may well have been but kept hush due to reputation and repercussion.

    The welds need ground out completely and redone, but without definite base material information you would be hoping the component materials are weldable.

    Stuart

  15. #15
    Guest ross@rmrrestorations's Avatar
    Join Date
    Jun 2003
    Posts
    4,668
    Well I,m sure all these yank parts are mild steel dom tubing and cold rolled flat plate. That's about as much info as you get from them.
    I bought the x-member second hand but new.
    As I said, all the other welds are fine and look to have more filler added.
    Whatever stresses may have been in the frame, or even just that x-member, will surely be relieved by this "opening up"
    None of my welds have cracked hence why I told him I would reweld everything.

    Total bummer though.........

  16. #16
    Moderator jsf55's Avatar
    Join Date
    Sep 2003
    Posts
    14,970
    Images
    59
    Having a think about this, but surley if one side has cracked, why would the other? all the tension should have gone ?

  17. #17
    NSRA member langysrodshop's Avatar
    Join Date
    Jun 2003
    Posts
    28,748
    Images
    53
    Ross have you cleaned any of the joints down to the raw steel yet ??? Be interesting to see
    Any advice or help given is actually based on having done the job, not read about doing it or Googling it.

    www.langysrodshop.co.uk Our parts are air freighted so 5-7 day delivery, The best GRP Willys body available/Rebel Wirings only UK dealer/Speedway Motors authorised dealer/Summit racing/Jegs/Hotrod parts supplied, MAC Autos, We deal with all the US hotrod suppliers even non car related stuff.
    Brake,Oil & Fuel etc plumbing stockist/Totally Stainless fastener dealer/Dolphin Instrument dealer, LMC & Brothers Trucks,
    Stainless Exhaust tube & mandrel bends stockist

  18. #18
    Admin IanT's Avatar
    Join Date
    Aug 2005
    Posts
    7,816
    Images
    55
    No, I'm not a welder either, but look at Picture C, page 8 of this paper on "Residual stress analysis and fatigue of multi-pass welded tubular structures"

    http://www.ultrasonicpeening.eu/Files.aspx?f_id=61492

    And is it possible the cracks have been there a lot longer - but the paint edges have only just lifted away to make them more visible now?
    IanT (°||°)
    "that Plymouth had a Hemi with a Torqueflite"

  19. #19
    Guest ross@rmrrestorations's Avatar
    Join Date
    Jun 2003
    Posts
    4,668
    I,m going to call the guy again today and get him to remove some paint, but he seems certain it is an actual crack on the tubes.
    After I painted it, it was in my yard for probably almost a year whilst I did other bits and pieces to make it a roller etc.
    When I sold it, it looked absolutely fine. I cleaned theframe up before putting the body on so would have noticed anything then.
    If it's the paint shrinking(2k over etch) why only on these tubes? All the other tube ends that go across the frame should have done so also...but they haven't.

  20. #20
    NSRA member langysrodshop's Avatar
    Join Date
    Jun 2003
    Posts
    28,748
    Images
    53
    Its only an educated guess Ross but i reckon when you clean it back you will find the crack is in the paint only Not saying its happened here but i have seen paint crack on welded joints where the paint hasn't adhered to the rod used. I hope !!!
    Any advice or help given is actually based on having done the job, not read about doing it or Googling it.

    www.langysrodshop.co.uk Our parts are air freighted so 5-7 day delivery, The best GRP Willys body available/Rebel Wirings only UK dealer/Speedway Motors authorised dealer/Summit racing/Jegs/Hotrod parts supplied, MAC Autos, We deal with all the US hotrod suppliers even non car related stuff.
    Brake,Oil & Fuel etc plumbing stockist/Totally Stainless fastener dealer/Dolphin Instrument dealer, LMC & Brothers Trucks,
    Stainless Exhaust tube & mandrel bends stockist

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •