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Thread: Weld cracking in dissimilar steels

  1. #51
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    Re: Weld cracking in dissimilar steels

    Quote Originally Posted by shovelon View Post
    This is the tig procedure I purchased from AWS.
    Holy cow, $200 for a set of instructions? Is that typical? I've paid less to psychics for winning lottery numbers.

  2. #52
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    Re: Weld cracking in dissimilar steels

    Quote Originally Posted by Kelvin View Post
    Holy cow, $200 for a set of instructions? Is that typical? I've paid less to psychics for winning lottery numbers.
    Welcome to the world of 'specs' and 'standards'

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  4. #53
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    Re: Weld cracking in dissimilar steels

    Quote Originally Posted by ronsii View Post
    Welcome to the world of 'specs' and 'standards'
    Like buying site prints to make a bid?

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  6. #54
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    Re: Weld cracking in dissimilar steels

    Quote Originally Posted by 12V71 View Post
    Like buying site prints to make a bid?
    That too

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    Re: Weld cracking in dissimilar steels

    Quote Originally Posted by Kelvin View Post
    Holy cow, $200 for a set of instructions? Is that typical? I've paid less to psychics for winning lottery numbers.
    Tig is not a prequalified process in AWSD.1 and D1.6. Since qualified procedures are required it is quite cheap to buy from AWS compared to qualifying the procedure yourself. Usually CJP coupons are welded to a set of parameters. Then sectioned, bend tested, tensile tested, and to apply to PJP joints macro testing is done to support the CJP s qualification. If passed the minimum acceptance criteria the time, material, and lab testing all before reports are written can cost anywhere from $2000 to $4000 depending on the joint, post weld heat treat or not, and material involved. I processed one this summer welding grade 50 steel to 304 and 316 stainless with various bevel configurations independently and the costs were over $15,000. Well worth the cost to complete a multimillion dollar project for my customer.

    Don't get me started on qualifying alum joints. Almost nothing is available for purchase.
    Weld like a "WELDOR", not a wel-"DERR"
    MillerDynasty700DX,Dynasty350DX3ea,Dynasty200DX,Li ncolnSW2002ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig4ea,MigMax1ea.

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  9. #56
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    Re: Weld cracking in dissimilar steels

    Quote Originally Posted by shovelon View Post
    Tig is not a prequalified process in AWSD.1 and D1.6. Since qualified procedures are required it is quite cheap to buy from AWS compared to qualifying the procedure yourself. Usually CJP coupons are welded to a set of parameters. Then sectioned, bend tested, tensile tested, and to apply to PJP joints macro testing is done to support the CJP s qualification. If passed the minimum acceptance criteria the time, material, and lab testing all before reports are written can cost anywhere from $2000 to $4000 depending on the joint, post weld heat treat or not, and material involved. I processed one this summer welding grade 50 steel to 304 and 316 stainless with various bevel configurations independently and the costs were over $15,000. Well worth the cost to complete a multimillion dollar project for my customer.

    Don't get me started on qualifying alum joints. Almost nothing is available for purchase.
    Wow, that's an eye-opener. Thanks for the info.

  10. #57
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    Re: Weld cracking in dissimilar steels

    Finally got them welded out.

    This was my procedure:

    Bolt up with the 7 bolts (not the arp studs I will use on vehicle), light tension.

    Pre heat to 300c, tack a each bolt (7 points around dia)

    check heat, weld out 50mm runs, checking heat as I went. I did not let it get below 270c and did not weld if it was over 310c.

    after root run was complete a quick wire wheel and check temp, bring back to 300c and repeat for second pass.

    remove bolts as fast as possible

    post heat up to 500c, and kept there for 30 mins. After that I kept a bit of heat on the end flange and housing so it would not wick the heat out too fast. Then when the weld was down to 250 let it air cool.

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  12. #58
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    Re: Weld cracking in dissimilar steels

    Quote Originally Posted by husq2100 View Post
    Finally got them welded out.

    This was my procedure:

    Bolt up with the 7 bolts (not the arp studs I will use on vehicle), light tension.

    Pre heat to 300c, tack a each bolt (7 points around dia)

    check heat, weld out 50mm runs, checking heat as I went. I did not let it get below 270c and did not weld if it was over 310c.

    after root run was complete a quick wire wheel and check temp, bring back to 300c and repeat for second pass.

    remove bolts as fast as possible

    post heat up to 500c, and kept there for 30 mins. After that I kept a bit of heat on the end flange and housing so it would not wick the heat out too fast. Then when the weld was down to 250 let it air cool.
    Excellent! Nice to see a plan come to fruition.
    Weld like a "WELDOR", not a wel-"DERR"
    MillerDynasty700DX,Dynasty350DX3ea,Dynasty200DX,Li ncolnSW2002ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig4ea,MigMax1ea.

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  14. #59
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    Re: Weld cracking in dissimilar steels

    Quote Originally Posted by husq2100 View Post
    bugger, I was hoping I was going to able to see it lol

    What are your thoughts on post heat treatment? Spec say 1 hour, ttoks is saying 8-12 (huge difference) and id be struggling to keep it there for even an hour?
    Sorry to come back to this so late.

    I was thinking of the WPS for a main steam B3 weld (36" internal diameter with a 6" wall thickness) the WPS for that is 12 hours for the round trip, bringing up to temp, holding for an hour and back down which takes 8-12 hours, I overlooked that small detail in my first post

    I would still be careful with that with the PWHT you were able to give it, 500C is far below what B3 normally needs, but Shovelon's guidance here is something to listen to, he has alot more experience with qualified WPS's than I do.

    With that said, I've seen improperly heat treated B3 welds fails in spectacular ways in service which is what makes me nervous.
    Last edited by ttoks; 01-18-2021 at 08:49 AM.

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    Re: Weld cracking in dissimilar steels

    Quote Originally Posted by ttoks View Post
    Sorry to come back to this so late.

    I was thinking of the WPS for a main steam B3 weld (36" internal diameter with a 6" wall thickness) the WPS for that is 12 hours for the round trip, bringing up to temp, holding for an hour and back down which takes 8-12 hours, I overlooked that small detail in my first post
    Holy cow, 36" ID pipe with 6" wall, what is that, like Schedule 10,000? It boggles the mind to even consider how much power could go through such a steam pipe...any idea what temperature / pressure the steam is? I bet it would cut through a pinhole like a water jet!

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    Re: Weld cracking in dissimilar steels

    Quote Originally Posted by Kelvin View Post
    Holy cow, 36" ID pipe with 6" wall, what is that, like Schedule 10,000? It boggles the mind to even consider how much power could go through such a steam pipe...any idea what temperature / pressure the steam is? I bet it would cut through a pinhole like a water jet!
    just as a visual, this one is only a 12" pipe going into the turbine steam chest (the main steam like splits into 6 12" lines going into the HP turbine), Pressure is 2400 PSI at 600C (1100 degree's F), as for power, as for power, 740'000 horsepower at the generator, probably closer 1million in thermal energy going through a main steam line.



    honestly it's probably more than 6", i've never actually measured it but a 9" grinder will only cut about 1/4 of the way through.
    Last edited by ttoks; 01-18-2021 at 09:23 AM.

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  19. #62
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    Re: Weld cracking in dissimilar steels

    That looks set up for narrow gap welding but the extended lip in the middle is to allow room to do the root pass? Is the root Tig welded or Mig and automatic or manual? I suspect there's some corrosion allowance as well. A friend of mine worked on some 400 ton cokers and the piping was 4" double extra heavy wall. They were using automated orbital Tig welders and had to be done to nuclear spec... meaning if the X-ray wasn't perfect, it couldn't be repaired. They'd have to cut the entire weld out and start over.

  20. #63
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    Re: Weld cracking in dissimilar steels

    That's a "J" prep. Allows access to the root with the stick rod while minimizing the number of fill passes compared to a bevel prep. There will be a standard gap in the prep.

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  22. #64
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    Re: Weld cracking in dissimilar steels

    It's a U groove (double J groove) which is a type of narrow gap welding. Was more curious how the root was done.

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    Re: Weld cracking in dissimilar steels

    Quote Originally Posted by Welder Dave View Post
    It's a U groove (double J groove) which is a type of narrow gap welding. Was more curious how the root was done.
    root is done with TIG with an 6" long tip cup to be able to reach all the way into the prep.

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    Re: Weld cracking in dissimilar steels

    That sounds like it requires some experience to do.

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    Re: Weld cracking in dissimilar steels

    Quote Originally Posted by Welder Dave View Post
    That sounds like it requires some experience to do.
    the welding itself isnt actually all that hard, the hard part is that they're always pre-heated to 280C (540F) so not burning your hands is the biggest challenge.

    also there isnt really any corrosion happening, the pipes are almost always hot, and a thick (like 3/32 thick) layer of scale forms on the outside, i've never seen one get pitting ect, failure mode is always cracking from heat cycling as the boiler comes on and off line for repairs or cleaning, a new bit of pipe generally lasts 20-40 years before they start cracking.
    Last edited by ttoks; 01-19-2021 at 09:10 PM.

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  28. #68
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    Re: Weld cracking in dissimilar steels

    Interesting, I know a lot of vessels add corrosion allowance. When I was working with a friend on a 2 -1/2" thick vessel welding the nozzle and repad it was pretty toasty. Used 2 tiger torches (weed burners) to preheat it and then poured pounds and pounds of 1/4" 7018. It was still hot when we came in for the next shift. It didn't help the repad was cut too big. Supposed to be 20" but cut for 24" nozzle. Shop figured it was cheaper to fill with weld than have a new 2-1/2" thick repad made. Repad also had to be cut in half because there wasn't enough room to weld the nozzle with the repad tied to the flange like most repads are. Time went by fast welding it though. Just pouring rod.

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    Re: Weld cracking in dissimilar steels

    Quote Originally Posted by husq2100 View Post
    Hey all,

    I started a thread here a while back

    https://weldingweb.com/vbb/showthrea...r-rod-for-709M

    but am getting closer to doing the job. Ill be welding some 709M (basically 4140) to the end of an axle housing flange. I do not know what the flange is made from.

    I hope to have a piece of each for test welding.

    I have ordered the correct filler rods for he 709M, but im concerned that there may be a problem with cracking and the axle flange material.

    When you get cracking in the weld with dissimilar steels, is the cracking obvious to the eye, or only seen by X Ray?
    If it were me I would use ER70S-2 and TIG weld it, no preheat other than the TIG torch until both base metals bond naturally. The reason is it is more forgiving and fights cracking, much better especially when you have two dissimilar materials, and with TIG we first blend the two base metals and then add the filler which connects them very well and becomes a material very similar to both metals. Chromoly is a very sluggish metal it starts to approach titaniums sluggishness, it resists heat.

    You can also preheat and use a 7016 ARC rod.

    You could also do ER70S-6 if you flame spray with Argon and also melt and bond the two base metals in the puddle, that would be a very good weld, the problem is getting penetration and an even weld, as well as having to keep it horizontal. As well as having problems starting hot enough without a run-in tab. Chromoly is a very sluggish metal it starts to approach titaniums sluggishness, it resists heat. That is why I TIG it slow and hot with only a little wire, mostly penetrating and blending.

    The Germans make a lot of custom electrical connections using a pipe with machined flanges made of 4140 that have to hold up very well, they use a much harder rod but to be honest I believe they will be subject to cracking. I was asked to examine the weld by a German machinist, it looked like a weld that was loaded and just waiting to crack but he was raving about it. You have to look at the weld as a weak point and because of the structure created by the weld, a hyper-strong point, and not just make the weld strong, but allow it to flex or it will certainly crack next to the weld and not plastically deform.

    Sincerely,

    William McCormick
    If I wasn't so.....crazy, I wouldn't try to act normal, and you would be afraid.

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  31. #70
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    Re: Weld cracking in dissimilar steels

    Quote Originally Posted by farmersammm View Post
    I guess first off..........this stuff ain't really supposed to be welded http://www.matweb.com/search/datashe...4e502e6f992c7d

    If it is welded, taking into account the nearest ASTM steel is 4140, it should be welded in the annealed state http://www.interlloy.com.au/our-prod...el/?output=pdf. If welded in hardened state, it's a bit more complicated according to the specs.

    Why you'd weld this stuff with TIG is beyond me, especially such a large piece that's gonna soak up a lot of heat. Most recommendations call for low-hy SMAW.

    Sorry, I guess it's SAE 4140
    It TIG's well, you just have to preheat with the TIG torch, bond the base metals, and move very slowly for good penetration. The ARC rod has trouble blending the base metals and penetrating even preheated but you can do it. It looks a little cold or you get undercut.

    Sincerely,

    William McCormick
    If I wasn't so.....crazy, I wouldn't try to act normal, and you would be afraid.

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  33. #71
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    Re: Weld cracking in dissimilar steels

    Quote Originally Posted by husq2100 View Post
    The above post of mine has the weld prep and root run of test piece. This one shows second, fill pass and break. Note, I penetrated edge of hole and bolt. Bolt snapped on removal , this is not an option!

    The reason for the funny start near right hand end is when I was welding I did a false start there, that is I started (wasnt thinking) then thought as the real pieces are round, there is no "end" to start on. So I stopped moved in a little and started again (hope that makes sense)

    2.4mm tungsten at about 45 degrees sharpened
    1.6mm filler
    300c pre heat
    140 amps for root
    160 for second and 3rd passes ( I just looked up my notes as I did this a little while ago, I thought it was 2 passes but notes say 3?)

    2nd and 3rd passes were done when test piece had cooled to 300c.
    Smear this on the bolt before you weld.

    https://www.amazon.com/Rectorseal-73.../dp/B008A3UFB8

    It is pretty good stuff.

    Sincerely,

    William McCormick
    If I wasn't so.....crazy, I wouldn't try to act normal, and you would be afraid.

  34. #72
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    Re: Weld cracking in dissimilar steels

    Quote Originally Posted by William McCormick View Post
    Smear this on the bolt before you weld.

    https://www.amazon.com/Rectorseal-73.../dp/B008A3UFB8

    It is pretty good stuff.

    Sincerely,

    William McCormick
    Good idea. Never occurred to me to use anti-seize.

    Thanks!


    Sent from my iPad using Tapatalk
    :

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  36. #73
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    Re: Weld cracking in dissimilar steels

    DMW cracking is another fabrication issue that can and does result in equipment failure. It usually occurs at the weld juncture where carbon steel or low alloy steels are welded to austenitic stainless steels in high temperature applications.

  37. #74
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    Re: Weld cracking in dissimilar steels

    Quote Originally Posted by Barclay View Post
    DMW cracking is another fabrication issue that can and does result in equipment failure. It usually occurs at the weld juncture where carbon steel or low alloy steels are welded to austenitic stainless steels in high temperature applications.
    That is why er309 is recommended. Personally I prefer er312. The both have the high ferrite content to deal reduce sensitization in Dissimilar Weld Metal joints, but I like the higher strength of er312. I will use 309L if the procedure or customer prefers it.
    Weld like a "WELDOR", not a wel-"DERR"
    MillerDynasty700DX,Dynasty350DX3ea,Dynasty200DX,Li ncolnSW2002ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig4ea,MigMax1ea.

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  39. #75
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    Re: Weld cracking in dissimilar steels

    Quote Originally Posted by ttoks View Post
    Sorry to come back to this so late.

    I was thinking of the WPS for a main steam B3 weld (36" internal diameter with a 6" wall thickness) the WPS for that is 12 hours for the round trip, bringing up to temp, holding for an hour and back down which takes 8-12 hours, I overlooked that small detail in my first post

    I would still be careful with that with the PWHT you were able to give it, 500C is far below what B3 normally needs, but Shovelon's guidance here is something to listen to, he has alot more experience with qualified WPS's than I do.

    With that said, I've seen improperly heat treated B3 welds fails in spectacular ways in service which is what makes me nervous.
    I went by the material specs and research into stress relieving. I figured your specs took into account the massive thickness and size compared to mine. And as for air cooling after I had my heated sand set up, I was concerned about it cooling too slowly and changing the crystalline structure (from what I read) again, spec said "air cool". I did how ever make sure that no windows or doors open in the shed, to keep heat outboard of the weld (until it 250c) being a tube and it would cool faster. And after all that oxy heat, the shed was hot lol
    Last edited by husq2100; 4 Weeks Ago at 12:48 AM.

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