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  • Stainless Steel Welding Problems...

    Hey guys,

    I'm definately new around here, and I just wanted to say the site looks great, and I'm sure I'll be back often to read over all the various threads...

    A little about me, I work in the machine shop at the local university (I'm also a student) and occasionally do a little welding when specific jobs come in that require it... mostly TIG and MIG...

    Recently, I ran into a problem when trying to TIG some 316 stainless... The joint configuration is just a 4" square plate of 316 stainless, 3/8" thick, with a cylindrical fitting welding on top... The fitting is also 316 stainless with a 1.5" OD, and 1" ID, and 1.5" length... The task at hand is to TIG weld the fitting to the plate by running a bead completely around the base of the fitting...

    The problem I keep running into is that the weld bead keeps cracking (longitudionally) down the center of the bead all the way around the fitting... Almost like its being pulled apart, and it just splits...

    I've even tried preheating the base metal to around 350F to no avail... The welding set up I have been using is a Syncrowave 250DX, 2% red (3/32 Dia.) electrode, 100% argon gas, 316L filler rod (1/16" Dia.), 130-150 Amps DCEN...

    There must be something that is going wrong because the model we're trying to replicate has a beautiful weld on it...

    If anyone has any ideas or could suggest special techniques for this type of application, I would greatly appreciate the help...

    Thanks!

  • #2
    Originally posted by Torque1018 View Post
    Hey guys,

    I'm definately new around here, and I just wanted to say the site looks great, and I'm sure I'll be back often to read over all the various threads...

    A little about me, I work in the machine shop at the local university (I'm also a student) and occasionally do a little welding when specific jobs come in that require it... mostly TIG and MIG...

    Recently, I ran into a problem when trying to TIG some 316 stainless... The joint configuration is just a 4" square plate of 316 stainless, 3/8" thick, with a cylindrical fitting welding on top... The fitting is also 316 stainless with a 1.5" OD, and 1" ID, and 1.5" length... The task at hand is to TIG weld the fitting to the plate by running a bead completely around the base of the fitting...

    The problem I keep running into is that the weld bead keeps cracking (longitudionally) down the center of the bead all the way around the fitting... Almost like its being pulled apart, and it just splits...

    I've even tried preheating the base metal to around 350F to no avail... The welding set up I have been using is a Syncrowave 250DX, 2% red (3/32 Dia.) electrode, 100% argon gas, 316L filler rod (1/16" Dia.), 130-150 Amps DCEN...

    There must be something that is going wrong because the model we're trying to replicate has a beautiful weld on it...

    If anyone has any ideas or could suggest special techniques for this type of application, I would greatly appreciate the help...

    Thanks!

    I'm not the best source on this but it certainly looks and sounds as if you're doing everything correctly.

    Some things come to mind: Could it be that you really don't have 316L for your base metal? 316L is perfect for 316L work but if not matched, there could be an issue. How about your gas? I've not had it happen but on other sites I've heard that sometimes the wrong gas is loaded or even contaminated.

    If it's not a mis-match on your metal, which I doubt because it sounds like you are sure about it, or if something is not wrong with the gas, I'm stumped.

    I'd sure like to know what's wrong so I'll watch and see what others may have to say. Maybe wait 'til after the weekend for more responses.

    Good luck!
    Miller Syncrowave 200
    Milermatic 252
    Lincoln AC/DC "Tombstone"

    Comment


    • #3
      Thanks for the reply Synchroman, but I'm almost positive that two metals used for the plate and fitting were both 316 Stainless... unless one was marked incorrectly...

      As far as the gas goes, I'm about halfway through this bottle and haven't noticed anything different about it when welding other projects...

      Comment


      • #4
        316 S,s

        One problem is the material thickness 3/8" to what is the thickness of the tube or pipe?Anyway doesn't matter.
        Tig is not ment for that thickness.However you can tig it of course; But the problem you have is called hot cracking.try using a 1/8 or larger tungsten instead.Your current beads are to small for the material being welded.
        Everything eles that you are using is fine.no need to pre-heat.I mean you can if you want but I would not.If this info does not help any I know a few other things that might.

        O ya A pic would be nice.Because on here I think everybody has a camera.And we sure do love pictures.Anyway nice to see a new member join.welcome.
        Last edited by Darmik; 09-04-2007, 07:46 AM.

        Comment


        • #5
          Hey Torque1018-

          What kind of joint preparation are you doing on the tube? Bevel, flat edge?

          For those thicknesses are you doing a root pass and a cap?

          Have you tried autogenuously welding the parts?

          What flow rate are you using for the Argon? How much post flow? What size gas cup or lens?

          One thing also comes to my mind but I'm not sure it would cause your problem...

          You say that you are using 316 SS and not 316L. 316 SS has a higher Carbon content, .08% than 316L's (the L stands for "Low Carbon") .035% max. The higher Carbon content might be causing the cracking but I doubt it.

          I can't imagine you would be getting Stress Corrossion Cracking unless something is causing cross contamination.

          Pics would really help....

          - Paul
          The only stupid question is the one that never got asked.

          Comment


          • #6
            Pictures

            Here's a few pictures of the problem at hand and the relative sizes of the parts being welded...

            The cylindrical fitting has a 1/4 inch wall thickness while the plate is 3/8 inch thick (4 inch square)... There was no bevel or specific joint preparation before welding the parts together, and I only made one pass to weld the part once tacked in place...

            ZTFab, I'm using about 18 CFH of argon with a size 9 (...??) cup with about 12 seconds of post flow and 145 amps DCEN...

            Also, I'm sure that the plate is 316L SS, but not too sure if the fitting is 316 or 316L... Could that possibly be something to worry about..?

            Thanks for the help guys!
            Attached Files

            Comment


            • #7
              Another Pic..

              The other picture...
              Attached Files

              Comment


              • #8
                Welding Stainless

                Cracking

                -You could try using E-318 filler metal

                - How many passes are you doing?

                - When you stop to weld the other side how big is the crater that you leave behind?

                - Before you stop welding to weld the other side do you fill your crater?

                - How clean is the material being welded?

                - How small is your first pass? Toe to Toe. Do you have a fillet gage?

                - Is the tungsten clean?

                - How long have you been at this kind of welding?

                - Place a piece of copper under the piece to draw the heat.

                - The carbon content of 304L and 316L is .03% and 304 and 316 contain .08%

                - Do you have "any" kind of gap before welding?

                - How small are the tacks?

                - How are you tacking the piece 3,6,9,12?

                - When tacking are you using a filler metal?

                - Are you clamping the piece down before welding?

                - You may need a trailing gas.

                -Restraining a joint too rigidly during welding so that all the stresses of expansion and contraction end up concentrated in the weld thus causing weld cracking.

                - The decision to try and weld to large a gap between the base metal can also cause cracking

                - Wrong electrode or filler wire can produce embrittling elements into the weld.

                - Too fast a welding speed will result in a long weld crater that will produce columnar grain growth at 90 Deg to the weldiment, which will cause crater cracks.

                -I could go on and on and on forever when you talk Stainless Steel this is a very in depth subject the same with Aluminum. I hope this helps ya out.

                Comment


                • #9
                  i do alot of stainless. don't be scared to crank your gas up. 18 sounds like it's a bit low turn it up to 35 or better. stainless warps real bad so, watch the pre-heat. i tig stainless low heat you really don't want a real fluid puddle like carbon.

                  Comment


                  • #10
                    I Remember This Felling

                    These Guys Have A Lot Of Good Ideas And They Are All Telling You The Truth And There Is A Lot To It And They Can Tell You What They Whould Do And We All Have Our Ideas And There Good

                    The One Good Idea I Have For You Is The One I Do And That Is Practis On The Same Materall To See What You Need To Do To Make It Work

                    I Could Tell You My Thouts Like More Filler Matteral More Gas And So On But That Is For Me You Need To Practis That Will Help A Lot

                    Good Luck And Remember We All Have Been Here

                    Comment


                    • #11
                      It sounds like you have a something other than 316 ss. See if a magnet will slightly stick to it. If it does it is not 316 or even 300 series. You should have been able to fuse around that piece with no filler without cracking. Wrong material (or filler rod)
                      Last edited by Cracker(Jack); 09-06-2007, 03:04 AM.

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