TIG weld consistency issues - porosity and rust color

[gearhead69]

The other night I was running some autogenous lines down a few little coupons, just practicing getting the arc started, checking the affects of different amperage and the like (using 1/8" mild steel). I had something odd happen, and realized it's been part of what I've experienced all along and not even known it.

I did a few beads and they looked fine - just a clean line. I went to do another, without making any changes, and the next line was full of porosity and had that rusty, brown discoloration all around it. The rest of them wen that way. I ended up with one good line and about six or seven terrible ones, and all on the same piece of steel. I was running the gas at around 14. From what I've been told, that's plenty for the job. Tungsten was clean, and I even replaced it for good measure and had the same on/off results.

I have had this happen on several different pieces of steel a similar way. Sometimes I can do two dozen and they'll all look fine, then I go to do another, and all of the sudden they're terrible, and nothing seems to fix it. The arc can become very hard to start as well at this time.

I'm guessing these are symptoms of gas flow issues? I tightened up my bottle to welder connections, which didn't seem loose, but what the ****. I then used soapy water on the entire hose and fittings from the welder to the torch - no issues.

First off, I guess my question is, are these issues related to gas flow or gas quality? Second, any thoughts on narrowing down the issue would be great. This is sort of driving me nuts. I can make a bunch of good beads, then go to do some real work, and all of the sudden all I'm doing is creating craters full of holes.

Many thanks.

[1havnfun]

well you may not need that much gas flow. You might be getting some turbulance at the puddle.
How many amps are you running.
are you using a gas lense or a regular nozzle. How big is the nozzle.
how far do you have the tungsten sticking out of the nozzle.
How far do you keep the tip of the tungsten from the work piece.
Are you running DC. sorry had to ask.

[Aerometalworker]

Brezzy work area? Any fans, open doors, etc?

[davedarragh]

TIG Issues

GH69: Couple of questions. What type of machine are you using, and give us a run down on your tungsten, amps, nozzle size, etc.

Secondly, if you are using A-36 mild steel, there is always considerable "mill scale" which creates problems, unless removed. Mill scale can create "turbulence" in the shielding gas, causing irregularities and subsequent porosity, due to poor gas coverage.

It's very possible, it could be a combination of several issues.

GTAW isn't as "forgiving," as stick or short-arc MIG.

Give us all your particulars, and we'll see if we can help diagnose the cause.

Here's some settings for you to try:

DC-

1/16" Thoriated or ceriated tungsten

95-125 amps

1/4" - 3/8" Nozzle

100% Argon @ 11 CFH

3/32" filler rod (70S-2)

Use a cup brush or knot wheel on an angle grinder, and wipe the debris clean.

[gearhead69]

Okay, here are some of the particulars:

-Miller Maxstar 150STH
-DC
-100% argon
-Amperage was varied between 60 and 95A
-thoriated tungsten
-.040 tungsten with a #5 cup (that's 5/16", correct?)
-also 1/16" tungsten with a #5 cup
-no fill rod
-work piece ground free of mill scale using bench grinder
-gas flow was changed between about 15cfh to 20cfh - it seemed to do better higher, but I didn't get to play with it long enough to see if that was going to continue. I only got to do about half a dozen lines before I had to quit, and it's just as likely to come out badly next time I strike the arc. I know higher pressure is not recommended, but lower didn't seem to be doing me any favors, so I just tried it for the heck of it.

[Coalsmoke]

If you have a clean picture you could post it would be a help. Usually what you are experiencing stems from a gas, tungsten, or material impurity problem. Do you have any 1/16" 2% ceriated? If so give that a shot and let us know. Also, be on the look out for other indicating patterns, ie. porosity starts after freshly regrinding the tungsten, would indicate a contaminated spot on the sharpening wheel. Keep in mind that you can cook A36 and it will no longer weld well. If you were to weld over the same HAZ area 3+ times and especially if you are running a little hot you can 'cook' the steel to the point that it will no longer produce clean welds.

[gearhead69]

I will try to get some photos shot, thanks. I don't have any ceriated tungsten, unfortunately.

Hopefully tonight I'll get a few minutes free and I can run some beads, see how things turn out. With my luck everything will go perfectly, and I'll have nothing to show but good welds!

Thanks for the thoughts on grinding tungsten. I *think* my wheel is clean - I bought it expressly for grinding tungsten - but perhaps while regrinding once I got something on it without knowing any better. I'll have to watch for that.

I have really been looking for patterns, but it seems I can make a great clean bead, go to a spot 1/4" away, and changing nothing, end up with a terrible weld. Perhaps I'm missing something. I'll have to make notes perhaps.

I do believe that the extension of my tungsten isn't too far out, but I will have to double-check that. I don't think my arc is too far either, but I'm new, so what do I know? I just know to keep it close, and if you get too close, well, you end up grinding tungsten, so it's basically just far enough back to keep from doing that.

[davedarragh]

Gearhead: 95 amps is a little high for a .040 tungsten. They're good up to 80 amps, but even that high, you should switch to a 1/16" You're either not getting enough heat to the work to make a bead, or it's too much for the smaller tungsten.

As a rule of thumb, for starters, tungsten stickout should be 1/2 the diameter of the nozzle, and arc length is the diameter of the electrode.

Keeping arc length consistent is the key to effective TIG welding. You'll experience "long arc" issues, the same as you would in SMAW. Sounds like this may be some of your problems.

Try a 1/16" tungsten at 120 amps, proper stickout and arc length, and it should work just fine. Turn your gas back a little.

You are moving the torch "into" your work, correct? (If you're right handed, moving from right to left)

Miller has an excellent GTAW handbook (in fact I recommend the Student Pack) available through this website.

Let us know how it goes.

[gearhead69]

Thanks to all the help so far. Below is a link to a photo of some of the issues I have been having. At least it will give you an idea of what my crap looks like. On the second to the left piece at the top you can see that there is a sort of Z-shaped weld that looks fine in the middle of all that rust. This is sort of typical of the kind of on-and-off problems I've been having.

The very next minute I can get some time on the torch I will be working with all the suggestions, but if the photo helps explain what I'm doing wrong, feel free to let me know. Thanks.

http://www.flickr.com/photos/22099580@N04/4501145901/sizes/o/

[gearhead69]

Okay, so here is a photo with some of the issues I had mentioned initially:

http://farm3.static.flickr.com/2790/4501145901_900a7550f2.jpg

You can see a good bit of that rusty-looking discoloration to a couple of the pieces.

Here is a photo of a piece I did last night following the instructions from everyone here:

http://farm5.static.flickr.com/4060/4503830015_e316bd67d7.jpg

The particulars:

-1/8" MS, thoroughly ground free of scale on a grinding wheel
-100 amps
-100% argon at 11cfh
-1/16" thoriated tungsten, extended .14 --- (yes, I got the calipers out and measured that so I would be sure to have it right!)
- #5 cup
- Except for the two lines with the arrows drawn next to them, I kept the tungsten as close as I could to the work without dipping it. For those two, as a test, I backed the arc way the **** away from the piece just so I could postitively identify the results of a weld that was done incorrrectly with too long of an arc.

I got a little porosity on two of those, but the rest look fairly decent. I haven't been able to practice enough again to be able to repeat those crazy failures from the other day like in the first photo. But if someone could eyeball those really rusty ones and let me know what you think might be going on there, that would be great - just the general sort of "Well, that happens when you do XXX" would be really good to know.

I am in the process of reading the TIG Handbook from Miller, but haven't found any definite answers to these questions yet.

Thanks again.

[jasonspoon]

Post a pic of your tungsten as well. In the rust colored pics, that's usually what you get with a contaminated tungsten.

Can you hear the gas coming from your torch? Try some welds with it incrementally higher & see if they get better. Make sure your argon bottled is wide open, some guys only crack it a little. I would make sure nothing is restricting your flow.

Does your torch have a valve on it? Make sure it is open, even if the machine has a gas solenoid.

J

[davedarragh]

Okay, so here is a photo with some of the issues I had mentioned initially:

http://farm3.static.flickr.com/2790/4501145901_900a7550f2.jpg

You can see a good bit of that rusty-looking discoloration to a couple of the pieces.

Here is a photo of a piece I did last night following the instructions from everyone here:

http://farm5.static.flickr.com/4060/4503830015_e316bd67d7.jpg

The particulars:

-1/8" MS, thoroughly ground free of scale on a grinding wheel
-100 amps
-100% argon at 11cfh
-1/16" thoriated tungsten, extended .14 --- (yes, I got the calipers out and measured that so I would be sure to have it right!)
- #5 cup
- Except for the two lines with the arrows drawn next to them, I kept the tungsten as close as I could to the work without dipping it. For those two, as a test, I backed the arc way the **** away from the piece just so I could postitively identify the results of a weld that was done incorrrectly with too long of an arc.

I got a little porosity on two of those, but the rest look fairly decent. I haven't been able to practice enough again to be able to repeat those crazy failures from the other day like in the first photo. But if someone could eyeball those really rusty ones and let me know what you think might be going on there, that would be great - just the general sort of "Well, that happens when you do XXX" would be really good to know.

I am in the process of reading the TIG Handbook from Miller, but haven't found any definite answers to these questions yet.

Thanks again.

Looks like those rusty one's were a result of too low of amps, with the smaller tungsten, and generally just poor torch angle and arc length.

Always have a good work clamp connection, when working with small, loose pieces. Work away from the ground (this holds true of any welding process).

Most importantly, make yourself comfortable. You'll have plenty of time to work in contorted positions. Position yourself, so you're comfortable at the END of the weld, with the best possible view. When learning, it's easy to start out like "gang busters," only to find yourself unable to successfully complete your weld, due to physical limitations (arms, hands, line-of-sight, etc.)

Try some pieces with filler metal, you'll find the results more rewarding.

[rezsst]

tig welding over 20 years. it looks to be to hot. i like to clamp it to other metal to help draw out some heat. let cool between passes

[gearhead69]

Thanks for all the help so far. It looks like things might be improving! I tried things again last night using all the same settings, only added the use of 3/32 ER70S filler rod.

The first one or two beads look a little they way I'm thinking they are supposed to look. After that, they kind of degrade. Anyway, if you could take a look and give your thoughts, I'd appreciate it. I noticed that I got a little pop and some porosity, and seemed to have some issues the more I worked with having the weld pool sputter and pop a little. I couldn't entirely get it to stop. Not sure what I was doing to cause that. The first weld went very smoothly, and I was happy with it as a start in the right direction.

http://farm3.static.flickr.com/2711/4516172029_7e7e023f60.jpg

Thanks again for the assistance. I think I'm making a little progress. I did do some tests based on what has been said about torch angle and tungsten contamination and found out just how much of a difference that can make.

[mdbreaux]

I am so pleased to see this thread becasue I just shut down my tig welding frustrated with the same problems. I can weld perfectly and then when I start again, nothing but porosity and brown discoloration. I am using an Arcmaster 185, 1/16 thoriated tungsten, 1/16 filler, mild steel lap joining 1/8 to 12 gauge, 75 amps, #5 ceramic cup. I welded several inchest perfectly, then porosity and brown discoloration. Then perfect, then problems again. Driving me crazy. I am also welding in the overhead position and it is not fun for a beginner. It does not make sense to me. I also tried a 3/32 tungsten with #6 cup. My gas fow is at 10 cfm, but it seems to work better with more gas flow - 12-15. I am outdoors, dead still air. I noticed my Argon went from 500 to about 400 by the end of the ordeal. SHould I get thge bottle filled now that I am below 500??? Any suggestions greatly appreciated. Oh yeah, my steel was grinded, wire brushed with a drill, then stainless steel brushed and repeatedly ss brushed between welds.