Announcement

Collapse
No announcement yet.

Problems with TIG weld quality on steel

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Problems with TIG weld quality on steel

    I'm pretty new to welding in general, and totally new to TIG welding. I was working on some practice pieces last night and having issues. The work is 1/8" mild steel rod, doing T-joints, no filler, 30 amps on the machine, 100% argon. Maxstar 150 STH if that's important.

    The first two joints seemed to really go fairly well, flowed together okay, at least for my (non)experience level. The six I did afterward were pretty bad, to the point that one of them refused to adhere at all. Mostly it seems like what ends up happening is that have to heat up the pieces way too much before they finally start to flow. A lot of my joints looked "overcooked," kind of scaly, and the piece is red hot once I'm done.

    Before attempting the welds I wiped down the steel good with acetone and then scrubbed it with steel wool. Perhaps I don't have the pieces in good contact with each other? They are touching, but it's not perfectly even across the face of each piece.

    What distance should I be shooting for between the tungsten and the work? Maybe I'm making too long an arc?

    I was watching very closely, while trying to make the joint, and I guess what I should be seeing is that the steel will form a little puddle like what you'd see when gas welding, and then both pieces will flow together. What I was seeing, however, was just a little bright point on one piece, and it wouldn't get any larger, just stay at that one small point, even if I moved the tungsten around. I couldn't get the weld spot to grow without difficulty, or until the whole piece was about to collapse from excessive heat.

    Any thoughts would be a big help. Many thanks.

  • #2
    TIG Tips

    Gearhead: You are trying what's known as an "auotgenous" weld (no filler metal).

    Your amps are way too low. Should be up around 100 (85-140)

    1/16" ceriated tungsten (sharpened)

    1/4" - 3/8" cup orfice

    3/32" filler rod

    argon flow 11 CFH

    As a general rule, arc length is normally one electrode diameter, and stick out is 1/2 the diameter of the cup.

    Miller has a TIG handbook (actually the Student Pack is recommended) available on line, as well as TIG calculators.

    My guess is, with your amps so low, you're taking too much time to get any type of weld pool going, and the subsequent results.

    Make sure the steel wool is wiped off, as well.

    With the proper amperage, it would only take a matter of seconds to fuse those rods together.

    If you can get some flat bar stock (2" wide) they make for great practice coupons.

    Keep in mind, if it's got mill scale on it, (like A-36) you'll have some issues as well. TIG doesn't like mill scale.

    Cold rolled plate, CREW, HREW, DOM is much easier to work with when practicing TIG.

    Keep us posted.

    Dave
    Last edited by davedarragh; 02-25-2010, 10:11 AM.
    "Bonne journe'e mes amis"

    Comment


    • #3
      Your heat sounds too low for 1/8", try something in the 60 to 80 amp range unless the pieces are ver small. Keep your tungsten sharp, if you dip it, repoint it, it does make a huge difference especially in getting the puddle to fuse the two pieces. Steel can be overheated easily as well and this will cause porosity. I have found that filler needs to be added when welding steel, especiall if it has been gone over before or you will get porosity. I use a gas lens setup, that helps some too.
      In my limited experience steel is harder to weld than stainless steel.
      It takes a lot of practice to get it down, its not hard once you get the basics, it would help a lot if you had someone to show you.

      Brushing is good on the cleaning, grind the area if its very rusty etc, acetone isnt needed in my opinion on steel.
      The puddle needs to be established relatively quickly as the base metal degrades if its heated for a longer period than necessary.
      On a "T" joint I would use filler on carbon steel and try to do it in one pass, try not to go over it again.
      Practice is the key, it just takes lots of it to become proficient.

      good luck
      mike sr

      Comment


      • #4
        YES! Thanks for all the specifics!

        davedarragh, Student Pack is ordered and on the way. This is exactly what I need to answer all these basic questions.

        popsipes, Yeah, I think I've familiarized myself fairly well with degraded steel and porosity (*shakes head sadly*).

        I'm surprised at the amp levels both of you have mentioned. I've been reading about some stainless artists that are using as low as 15A! One guy said he was using 60, but I've not heard higher. I'm not going to argue at all, however. What I'm doing isn't working, and you guys know a lot more than I, so I have no problem trying something else. It is definitely taking way too long to get a pool going.

        I may pick up some flat stock for coupons and try burning those up a bit as well. I plan on doing a lot of work with rod, but for starters it can't hurt to just make long beads.

        Comment


        • #5
          TIG Tips

          Gearhead: Glad we could help. Stainless settings generally run 10% lower than mild steel, hence your associate's different settings.

          Good fit-up and joinery is also important with GTAW.

          Good luck and post some of your artwork when you get a chance.

          Dave
          "Bonne journe'e mes amis"

          Comment


          • #6
            I didnt see that you were welding rods together, that would require less heat thats for sure.
            One thing to look for at least on small parts is when it starts to get overheated, the base metal will throw off small sparks, once it does this the base metal is degraded and you will get some porosity, to get it to weld correctly I add some filler to kind of fix the problem. Its much better to not overheat the base metal to start with.

            A fresh prepped tungsten will bridge the best, if its contaminated it will make it almost impossible. Iusually use a sharp point on higher currents, on very low current I use a bit of a flat on the tip, cuts the arc wander with the small flat. I also use pulse on the low currents as my tungsten tip lasts longer.

            I might add that welding steel is new to me too, I have done years of stainless tube, and its similar but not the same, the steel I have only done for about 3 years or so, again there is no substitute for practice........

            Dave is one of the best on the specifics of welding.
            mike sr

            Comment


            • #7
              I didnt see that you were welding rods together, that would require less heat thats for sure.
              One thing to look for at least on small parts is when it starts to get overheated, the base metal will throw off small sparks, once it does this the base metal is degraded and you will get some porosity, to get it to weld correctly I add some filler to kind of fix the problem. Its much better to not overheat the base metal to start with.

              A fresh prepped tungsten will bridge the best, if its contaminated it will make it almost impossible. Iusually use a sharp point on higher currents, on very low current I use a bit of a flat on the tip, cuts the arc wander with the small flat. I also use pulse on the low currents as my tungsten tip lasts longer.

              I might add that welding steel is new to me too, I have done years of stainless tube, and its similar but not the same, the steel I have only done for about 3 years or so, again there is no substitute for practice........

              Dave is one of the best on the specifics of welding.
              mike sr

              Comment


              • #8
                Thanks, popspipes. Yeah, um, about those sparks? Seen those on a few occasions. I knew that wasn't right without even asking. I figured it was a sign of "been sittin' on this thing too long."

                Probably time for me to resharpen the tungsten, too. One of 'em I balled up, and I didn't realize at the time I should cut it, so I just resharpened it. I think I may have balled it by accidentally dipping it in the puddle. Can't hurt to cut it and start over.

                Comment


                • #9
                  Yes, if the tungsten is contaminated resharpen or cut off the contaminated end and resharpen, This is very critical on all tig welds especially steel.

                  I do the .020 .030 steeel stampings, and it is very critical on those.
                  mike sr

                  Comment


                  • #10
                    Originally posted by gearhead69 View Post
                    Thanks, popspipes. Yeah, um, about those sparks? Seen those on a few occasions. I knew that wasn't right without even asking. I figured it was a sign of "been sittin' on this thing too long."

                    Probably time for me to resharpen the tungsten, too. One of 'em I balled up, and I didn't realize at the time I should cut it, so I just resharpened it. I think I may have balled it by accidentally dipping it in the puddle. Can't hurt to cut it and start over.
                    Sharpen up a bunch. Try for consistency in the grind so when you goober one, you can swap it and keep going without noticing a difference. I tend to keep half a dozen or more ready to go in whatever size I am running. Sometimes I'll go all day on one or two (they do 'wear' in use. You eventually notice that the arc starts hard and wanders, even though the pint still looks basicly ok), other times a few minutes a piece and I do a stupid. Especially in an awkward position, or if I am wound up, or had too much coffee, or....

                    When you grind, be sure that the grind lines run with the tungsten, not around it. If you grind around it, the tip is more likely to spit off. Also, a small flat, rather than a needle point is recommended for pretty much all applications. A needle point tends to spit off into the weld.

                    I would suggest about 50 to 70A for rod this size, 1/16 or 3/32" tungsten., with the flat about 1/64". When you start, the puddle should form in a second or so, and for fusing rods this size, maybe three second arc time total.

                    If the tip spits, or you dip the tungsten, grind out the tungsten from the weld. In some applications it is BAD to leave it (can lead to cracking), but, even when it really doesn't matter, it is good practice to grind it out.

                    Comment


                    • #11
                      All right, so I got some time back on the box last night, and the information here really helped! I have learned in drag racing, that you pretty much want to change just one thing at a time so that you know what is affecting what. Since I have so many things I could be doing wrong, and I want to know how the weld looks when I do them wrong, I just changed one thing. I upped the amperage.

                      Last night I was welding at 75A instead of the previous 10A. I made sure my CFH was about 15. I also focused on keeping my arc short. Things went much more smoothly. Heat did come on a lot quicker, but I only came close to burning through one time. I was able to get in about fifteen welds last night, and while many of them are still bad, they are much better than the disasters of the night before. I got fusion on all of them, and the very last two that I did almost look like what you would want a weld to look like!

                      I picked up a little 1/8" flat stock last night to cut into coupons so I can work on those a bit. This weekend I will work on some other things, like getting my tungsten sharpened up properly. I probably need to pick up a few extras of those, as mine came with only one of three different sizes.

                      One thing I noticed which I'd like some feedback on: When I do a T-style joint and I'm doing autogenous welding, is it common for there to be a sort of dished look to the weld, like sunken a little? I had a few look like that, and I'm wondering if that's normal, or if I'm doing it wrong, causing the bead to sort of collapse.

                      Comment


                      • #12
                        "T-Bar TIG"

                        gh: Have you tried "coping" the end of the rod? You'll get much better results if you have a good fit. Take it to a grind wheel, and make a concave so it mates tighter with the "T" rod.

                        Dab a little filler, autogenous is normally used on thinner material (sheet metal).

                        See how that works for you.

                        Dave
                        "Bonne journe'e mes amis"

                        Comment


                        • #13
                          Good point, Dave. I have not tried coping yet, though last night I was clamping the pieces together to make sure they were absolutely positively touching. I will have to cope some joints and see how they turn out.

                          What do you recommend as filler for mild steel? All I've got lying around right now is 308 for stainless filler.

                          Comment


                          • #14
                            TIG Wire Filler

                            Originally posted by gearhead69 View Post
                            Good point, Dave. I have not tried coping yet, though last night I was clamping the pieces together to make sure they were absolutely positively touching. I will have to cope some joints and see how they turn out.

                            What do you recommend as filler for mild steel? All I've got lying around right now is 308 for stainless filler.
                            Get you some ER70S-2 carbon steel TIG filler wire. It's only about $4/lb. Keep some 1/16" and 3/32" on hand, as those are what is used most. If you plan on some real small work, .045 is commonly available.

                            Dave
                            "Bonne journe'e mes amis"

                            Comment


                            • #15
                              Originally posted by davedarragh View Post
                              Get you some ER70S-2 carbon steel TIG filler wire. It's only about $4/lb. Keep some 1/16" and 3/32" on hand, as those are what is used most. If you plan on some real small work, .045 is commonly available.

                              Dave
                              I use the .023 wire version for the sheetmetal I work on. I use a piece of 1/16" copper tube about a 16" long to keep it relatively straightened out, just feed a short length of the wire thru it.
                              mike sr

                              Comment

                              Working...
                              X