Questions-learning the hard way

admin

Hello to all,      I have been here for awhile, I have learned most of the key posters names.  I am new to welding,  I have a new tig machine to do some work on a pontoon project, a mix of aluminum and stainless parts.       I am struggling with the stainless.  I have done some searching and have tried most of the common things.  When I am welding T joints they look gray overheated. If I just do a fusion weld (no filler?) they look great.  If I just run puddles with filler (308L) they look great.  When welding the T joint I get ( Key holing?) poor filling in the base of the joint unless I really pour the heat too it.  Then I get  poor looking welds, very gray ruff looking.  Shouldn't be bad gas/plate as the fusion only welds look too good, shouldn't be the filler/plate as the puddles look good.       Others have had this problem and posted but they didn't post the solutions they found.  I have tried more stick out, less stick out, gas lens, larger tungsten, smaller tungsten, faster/slower.   To get good fusion I get gray crappy weld.  Would be happy with smooth nice gray weld but not ruff cooked mess.  As strong welds aren't all pretty but would be nice if they looked better.1/8 stainless elevator fixture platesdynasty 2001/8 thoriated  W/gas lens parts cleaned sanded acetone wash100% argon 1/8 308L140 amps but using a pedal Thanks ahead for any other suggestions.  Sorry no Pics,                    Tim
Reply:If you're key holing you could be getting contamination from the unshielded side possibly. If you can get pics it would be a great help. Sounds like you're not getting your tungsten down to the root of the weld so you're moving slower to try to get the puddle to flow to the root, which is overheating your plate and causing the hole. Get some 3/32 tungsten (more suited to 140 amps). Sharpen it then put a flat on the end if you don't already do that. If you do already put a flat on the end, try making it a little bigger, that will give you a little more penetration in the middle of the weld puddle, right where the root is. Give yourself a little more stick out if you need it to get right down into the joint. Use the pedal and give it just enough heat to get the surface to melt. Wait for the two pieces to flow together, maybe washing back and forth slightly, befor you add filler. Once you start adding filler give it more power. Keep your're tungsten down as close to the root as you can. You have to keep in mind that stainless doesn't flow quite as smoothly as regular steel. It's kind of thick, not as watery, so it doesn't like to flow to the root, unless that's where the heat is.Going out on a limb with this advice. I'm going to guess that you have the top of your T flat on a work surface with the leg of the T sticking up, and that it's the leg you're blowing through. If that's the case, try putting a piece of copper behind the weld. It will act as a heat sink so your two pieces are heated more evenly, and will act as a shield to reduce the risk of the back being contaminated.Hope that helps.
Reply:Originally Posted by novisionHello to all,      I have been here for awhile, I have learned most of the key posters names.  I am new to welding,  I have a new tig machine to do some work on a pontoon project, a mix of aluminum and stainless parts.       I am struggling with the stainless.  I have done some searching and have tried most of the common things.  When I am welding T joints they look gray overheated. If I just do a fusion weld (no filler?) they look great.  If I just run puddles with filler (308L) they look great.  When welding the T joint I get ( Key holing?) poor filling in the base of the joint unless I really pour the heat too it.  Then I get  poor looking welds, very gray ruff looking.  Shouldn't be bad gas/plate as the fusion only welds look too good, shouldn't be the filler/plate as the puddles look good.       Others have had this problem and posted but they didn't post the solutions they found.  I have tried more stick out, less stick out, gas lens, larger tungsten, smaller tungsten, faster/slower.   To get good fusion I get gray crappy weld.  Would be happy with smooth nice gray weld but not ruff cooked mess.  As strong welds aren't all pretty but would be nice if they looked better.1/8 stainless elevator fixture platesdynasty 2001/8 thoriated  W/gas lens parts cleaned sanded acetone wash100% argon 1/8 308L140 amps but using a pedal Thanks ahead for any other suggestions.  Sorry no Pics,                    Tim
Reply:as grimm1 is saying, you must shorten the arc length.
Reply:What is going on under the part?? You can have bad gas coverage and get drafting from under your part; it may bring int he gray coloring. If you have an open area under, maybe use simple tin-foil as a buffer to keep sheilding gas contained there a bit. Hard to say. I am thinking you are moving a bit too slow, and as such overheating the part. That will gray it out every time. SS= less amps, and concise movement. Not necessarily fast, but deliberate and smooth.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:You are either pulling in contaminates to the weld pool or getting it too hot. Your range of 100-140 amps is pretty broad, must be using a pedal? Hard to give heat advice with that big of range. I really have no idea what you are actually running. Stainless will not cooperate if it is hot.
Reply:Thank you for the repliesA couple more questions.  One of Grimm1 suggestions is a little more stick out / (weld bead )less arc length.  I am having a hard time not hitting the puddle with the tungsten.  If I just use the tungsten to make the puddle I am fine (fusion looks good) but when I add filler it fills out on too the tungsten.  Are you guys moving electrode in and out as well as along or just along.  1/8 ss would like 1/8 fillet weld how far away are you. do you  heat it up, pull away, fill puddle, move forward and  in. Or just moving along making puddles and filling  move make puddle and fill?Rojodiablo suggested blocking in back.  The pieces are just sitting on another does the puddle suck the contamination in?Tin foil backing like hvac guys use or cooking stuff.  I am using a gas lens and 15 cfh of agron do I need to make an air dam/ gas shield? do others do this kind of thing. As far as being smooth concise. I am new at this and the hand/motor skill are slow in coming.Thanks for the tips will try smaller tungsten and a gas shield and practice on smooth Tim
Reply:You would be using the tin foil Rojodiablo suggested to make the "air dam" to keep air from contaminating the back of the weld. I would use the regular cooking stuff, The HVAC tinfoil tape has adhesives which will burn and cause more contamination.As for my advice for more stick out/less arc length. I don't move in and out. Tig is a process that requires alot of finesse. As some one new to it, you are probably going to stick your tungsten in the puddle alot. Frustrating I know. Drove me insain, when I was in school they only gave me one piece of tungsten. They told me only having one would teach me to keep it clean. Having to regrind your electrode every couple minutes teaches you real fast to keep a close eye on your arc length. For your arc length, you'll want to balance it between having it close to the root, but not so close you're dipping the tungsten in the puddle. I suppose if you want to move in and out you could, but I'm not sure I would recomend it, because then you aren't learning to balance your arc length.What size filler are you using by the way? 3/32 would be good, 1/16 may be better, your puddle wont fill out to the tungsten as fast. Plus you can get it down to the root a little more easily.Another thing to watch is your torch angle. That's  some thing else new tig welders have a problem with. Angle makes alot of difference in how your puddle flows. Unfortunately I do every thing by intuition now. I'd have to go weld a sample similar to what you're doing, then put a protractor on my torch to tell you what angle to use. Maybe JohnnyWelder or some one can supply some more numbers for recomended torch angle.I'll say it again, if you can get some kind of pics, it would be a great help to understanding your problem.
Reply:Novision    I'll start by saying I rarely tig myself and most of my experience is from oxy/fuel welding and tig when I went to school.  My first suggestion would be to pratice on MS since its more forgiving then SS or Al, get your basics down and pratice, pratice, and practice.  Then when your comfortable then move on to the others steels.  Second, see if you can find someone in your area to teach you what to look for and help you learn.