[steamtrac]

Guys,
I really hope you experts here can give me a little help. I am a total newbie to TIG welding, but my desire in building a custom exhaust for my 2 stroke bike lets me take the effort
In preparation I am currently doing some other jobs, so that I learn the TIG welding technique on the fly. I have some “minor” quality projects to do in the workshop, eg some brackets or fixtures or other stuff. I hope I will earn my skills here, so that the exhaust will get perfect.

I was building a piece in 1015 (here in Germany this material is called St37 due to the strength of ~370 N/mm²). So a low carbon steel, which should be easily weldable – at least I thought it is. I have heavy problems with porosity. Some pictures are attached, they show the first pass, which looks horrible, and the second pass, which looks slightly less horrible.
When the puddle starts, it seems that gas is boiling out of the base metal. The puddle looks like a boiling pan of water. Adding filler rod makes it a little bit more calm, but not much.
I have checked everything, but before any question comes I do a summary:
• I am using the grey type tungsten, 2.4mm diameter, the tip was ground to a ~30° taper, grinding marks in axial direction.
• The base metal is 4mm, 1015 low carbon steel
• I used about 100A
• I am using Argon 4.6 as shielding gas.
• I used a no. 8 gas cup
• the tungsten tip was sticking out ~4mm
• I have varied the gas flow, without noticing big differences in the result, between 6 and 12 l/min
• I have checked the torch, hoses and gas regulator. It is gas tight. No leaks detected.
• I use a filler rod suitable for low carbon steel (although the problem is clearly coming from the base metal)
• I have tried stainless filler rod, which did not make things better. The stainless rod is not flowing like the low carbon rod.
• I am working inside, the welding table is not in a windy area. I would call it totally calm.
• The base metal had a temperature of approximately 20° C when I started, I did not see any water condensing or vapour or anything.
• I did grind the weld area before I have started. I also degreased with acetone – so the weld area was totally clean.

The porosity is really heavy and not acceptable, I must be doing something wrong. Can anybody help me here? What should I do different?
The most surprising to me was when trying a piece of 1.3mm stainless. I have left all settings identical, I have only cranked down the amperage, and changed to a stainless rod. The piece stainless welds beautifully! No porosity at all, a very quiet puddle, no spatter, no nothing. This was really a difference like night and day.

Does somebody have any idea what I am doing wrong? It must be possible to do a clean weld on 1015!
Thank you all!

And I want to thank Jody, who makes these excellent videos every week, I really enjoyed watching them.

Boris

firstbead.jpg (47.81 KiB) Viewed 1395 times

secondbead.jpg (45.93 KiB) Viewed 1395 times

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[AKweldshop]

Welcome to the Forum Boris
John

[noddybrian]

Welcome to the forum

The good news is it sounds like you have sound preparation of the parts & the basics of setup - a few things spring to mind looking at the pictures - the heat affected zone seems very big & the bead is slightly lacking fusion in places - I would think that 100 amps is low for 4mm thickness so your travel speed is too low to compensate - try upping the amps to 1amp per thou of thickness ( approx ) and going faster while maintaining the shortest arc length you can - but I suspect it's gas that's the problem - even the stainless is showing gas issues & / or overheating - listen at the torch to confirm adequate flow or better yet buy the gauge mentioned in several previous posts that sits on the ceramic cup - I think the big question though is what the heck is " argon 4.6 " - I've never heard the term - but it worries me the 4.6 likely refers to a % of some other gas - you need PURE ARGON - never a mix ( OK except some blends with helium for specialty stuff ) maybe you could clarify what the gas is in case I'm wrong - sure others will chime in their take on you problem.

[steamtrac]

Hi,
Thanks for the first reply. Argon 4.6 seems to be the german describtion, I have googled it, delivery conditions state that it contains 99,996% Argon, so I would state this as pure.

Yes, maybe I should double check with a flow meter if the pressure gauge is really reading the correct value, but listening to the sound the escaping gas at the torch makes, I think it can`t be too wrong.

I wasn't aware that a too slow travel speed may be an issue, me being a newbie defenetely likes slow speed But with the 1015 it is really so, that the gas comes out the base metal as soon as the puddle starts...

I really have no clue how I could improove things.

[noddybrian]

OK - sorry I did'nt know what the gas was - different countries & suppliers have different names - really not sure why anything would boil out of new cleaned steel though - only time I had an issue like this the steel was a " free machining " type that contained a high lead content intended to improve surface finish when turned / milled - this played havoc with welding & was not really suitable for the job - I'm sure Otto or someone with more Tig experience will have the answers you need.

[Otto Nobedder]

steamtrac, I'm going to throw a couple of silly questions/ideas out there.

When you ground and cleaned the parts, did you do the entire end of the flatbar, or just the face being welded? (Oils and contaminants will boil off the end, or even around the end from the back side.)

The "frosty" area around the weld reminds me of an aluminum weld. If your machine has high-frequency, make sure it's set for HF-start, and not HF continuous. I doubt this is the case, since the stainless beads seem fine.

Just for fun, try running a few beads on one piece of the 1015, like you did with the stainless. If you have trouble, you'll know it wasn't the prep of the joint.

One other possibility... In a fillet joint like that, it's easy to get too much torch angle trying to get a good view, and draw air into the joint from the force of the gas flow through the "vee" formed by the parts.

I agree the heat-zone is really big, but too much heat isn't likely to cause the initial problem with porosity.

I'll look up the analysis of that alloy, just in case, but I believe all the 1XXX steels are TIG weldable.

Good luck,

Steve S

[Braehill]

Boris,

I've actually had the same exact problem with brand new mild steel angle iron. About ten welds did the same thing. I used some 309 rod I had on hand and got it to weld out. When I checked up on the steel it was made in China. I asked my steel distributor if they had any steel made elsewhere and it welded just fine with the same exact settings, gas and all, though not sure where it came from as it was not branded.

Len

[Arizona SA200]

As with Otto Nobedder I think this may be a torch angle issue. Too much torch angle creates a vacuum behind the cup that draws in outside atmosphere. I see you are running a #8 cup but is it a collet body or gas lens. I try to run a 10 to 15 degree leading angle when possible but the gas lenses are more forgiving than the collet bodies are.

[AFSATCOM]

What filler wire are you using? SG2?
Were there any coatings on the metal?
You anywhere near Bitburg?

[Mike]

Welcome to the forum Boris.

[Markus]

Check your gas hoses one more time, just for double check. Also switch your torch parts to new one, if you have. Just to test those. That back gap, gas lens and teflon insulator.

What comes to argon 4.6 by AGA. It's actually over clean in this case.
Here in europe we have standard argon, then a little bit cleaner 4.6 and also super clean 5.0. There is none mixtures in these, just plain argon. However AGA also offers Mison argon, which is basicly plain regular argon too, but with 0.03% nitrogen monoxide (NO) added. Mainly because of ozone etc...

I hope you can sort it out soon


More about mison argon in this pdf:
http://www.google.fi/url?sa=t&rct=j&q=& ... 4564,d.bGE

[Braehill]

Guys,
The 4.6 designates the Argon has four 9's and the 6 in it's purity (i.e. 99.996) and the 5.0 is 99.999 or five 9"s as it's called in the gas world. Unless you're welding with a laser you're not going to see the difference between 40 PPM of impurities and 10 PPM. The standard for industrial grade liquid Argon in the US is 99.997 or greater but a cylinder filled off of a liquid tank may well end up in the 99.996 range.

Hope this helps.

Len

[steamtrac]

All,
Thank you for the kind comments so far.
I understand the torch angle issue theoretically, and as I am really inexperienced this may be the failure. But I have a question concerning this:
Isn’t the Argon carrying the arc? I remember a situation, where the shielding wasn’t good, and I could immediately recognize this, as the arc became unstable. Also, the colour of the arc changed. I saw funny rainbow colours which appeared very erratically.

So, can it be that a insufficient shielding can cause porosity, without noticing it in the arc colour and appearance?
Thanks.

[Arizona SA200]

You are correct when you speak of lack of shielding gas, the arc will become erratic. If this is not the problem then that leads me to believe either base metal or filler. Clean everything with acetone and see if you get better results.

[paul_s]

Welcome to the forum.