Problem with TIG

[bmzero]

Setup: Lincoln Precision TIG 185
Joining 4130 and Mild Steel
30 PSI on gas
150 on output setting

A couple of days ago I ran out of gas. So I took the tank back to my local filler. He asked me if I needed pure Argon and I said yes. I wasn't really sure, but I'd never heard anything about an Argon mix. I brought that tank home and began welding. Immediately I began having problems with gas bubbles rising out of the bead. I assumed it was a problem with the "pure argon" so I headed to Google. I found a few people recomending an Argon mix for ferrous metals. I assumed that was the problem so I took the tank back today and swapped it for a mix tank. This time I swallowed my pride and asked what I should have. He said I did need the mix and gave me a new bottle.

Problem solved, right??? Nope! I'm still having the same issue. I have also noticed a very visible redish color ring around the bead. I've seen this bead before when the gas has run out.

Can anyone steer me in the right direction here?

Here's what the bead looks like, after I ground the first bead out with an angle grinder.



thanks,
.brit

[Bob Sigmon]

Brit,

With 99.999% of TIG you use straight argon! With aluminum you could use an argon helium mix.

Gas flow is in cfh (cubic feet per hour). 30 cfh is too high and probably dragging atmosphere into the shielding gas. 15 - 20 cfh is plenty.

If your tank has a gas mix take it back and get straight argon. Clean you base metal and filler (for 4130 you should be using ER80-D2) with a stainless brush and then wipe with actone (not other thinners as they leave a residue and will cause problems).

Good luck and let us know what happens for you.

[bmzero]

Here's the thing I can't figure out. I've been using this welder and for the most part, the same settings for about a year now. The work I do is mostly the same metal and thickness, so things don't change often. I haven't had any problems until this last tank switch. So, I have to believe it's a problem with the gas.

It's possible that when I got the first tank, it was actually a mix tank (accidentally) and when I brought it back and asked for another mix tank I actually got another mix tank. That would put me with two tanks of mixed gas, both causing the same results.

I will try the welding shop again today and see if they can help me get it straight today.


thanks for the info,
.brit

[diesel]

What kind of gas did you get? That red oxidation looks purty. The popping/bubbling could have been a result of your lines not being completely purged. Make sure the sticker on the tank says Argon only.
d.

[Bob Sigmon]

Brit,

I think you hit the nail right on the head! If the first tank was a mix it would tend to cause the type of oxidization that you are experiencing around your welds and lots of porosity.

Good Luck!

[OldSparks]

Just a word to any newbies about porosity in general. What's showing in the picture has to be ground out entirely to the full depth and a little extra on either side or else it will reoccur when you weld over it. You can usually get away with welding over mild porosity when stick welding, but tig welding has no forgiveness.

[Bigger Valves]

Brit,

With 99.999% of TIG you use straight argon! With aluminum you could use an argon helium mix.

If your tank has a gas mix take it back and get straight argon. Clean you base metal and filler (for 4130 you should be using ER80-D2) with a stainless brush and then wipe with actone (not other thinners as they leave a residue and will cause problems).

Good luck and let us know what happens for you.

Bob,
Argon/He mix can be used on any metal and not just aluminum. It has a few different characteristics depending, but it creates a hotter arc no matter what you're welding. I'd also prefer er70s-2 for normalized 4130 and definately suggest it heavily for 4130 to MS welds.

[blueoval557]

not to go against Bob, but I agree with the ER70-S2 filler for 4130. thats all ive ever used and i know thats what all the big name drag car chassis builders use...
Kyle

[Bob Sigmon]

No argument from me. I have just read in a number of different sources that the ER80 is closer in tensile strength while the ER70 has better enlongation characteristics. If the frame is controlled by a particular governing body, they usually specify weld type, filler, etc.

Thanks of the info on the heilum mix. I do know that you don't want any CO2 mixes and that's probably what Brit got.

[blueoval557]

Bob, I have done the same reading. I read that 80-S2 is actually closer in strength to 4130 base metal is than 70-S2, but that the 70-S2 allows more flexibility. And that 80-S2 wont flex at all in an incident of an accident, while 70-S2 will.
Kyle

[bmzero]

Thanks for the good information guys.

I went back to the shop and got another bottle. He assured me that this one was pure Argon, but of course there's no sticker on the bottle to verify. I guess I'll just give it a shot once more.

As suggested earlier, I will try to grind out most of the original weld. I was afraid that may become an issue so that's why I gave it a shot before. Thanks for the heads-up on that.

It will be a few hours before I can get back to my shop and do some welding. I will post the results of the initial run to verify the problem was with the gas (hopefully).


thanks again,
.brit

[bmzero]

Well, bad news. The gas wasn't the problem.

The new bottle, which does have a sticker labelling it "Argon", still helps to create the redish orange film around the bead. I'm all out of ideas.


Any thoughts?


thanks,
.brit

[RcRacer]

Now that you've eliminated the gas, you probably need to look at the gas fittings into the welder, the solenoid and the torch to see if you are getting a good seal or you will get atmoshere introduced into the gas. That can give you the symptoms you are seeing.

[Conrad_Turbo]

Try a new piece of metal? See if it happens again.

[Bob Sigmon]

Just a quick thought - did you check to see that all the connections on the torch and the consumables are tight. If they are loose, you can draw atmosphere into the argon. Also do you have any build up in the cup? That could cause problems.

You said that you have been doing these weld previously, have you changed any part of the prep stage?

You might try some stainless filler if you have any around. 308L has been known to help in some situations with mild steel.

Have you tried welding on some random scrap to see if it is doing this on everything or just what you are working on?

I'm not really sure where to go from here. Maybe some of the more experienced guys will have some thoughts.

Sorry that you are have this problem. I hope that you get it worked out.

(I see that some other have had the same thoughts while I was typing)