Urgent advice needed by novice tig user

[kiamaian]

Hi,

I live in Australia and I am using a new Sihio DC Inverter TIG WSM-200 which I believe is correctly connected.

I am having difficulties when I try to tig weld mild steel using 3/32" lanthanated tungsten electrodes. The tip of the electrode does not keep it's shape for more that a couple of minutes and become blunt and the arc then becomes unstable.


I am also getting a yellow powder stain around the weld. I am using argon shielding gas set at about 8 liters/minute and a no 8 alumina cup with the electrode protruding by about seven millimeters. I am using new clean 2mm mild steel fill in rod. The current is set to about 75 amps. I have tried reducing the current but the welding process is then painfully slow.

When I press the finger trigger on the torch I hear the noise of gas escaping and I am certainly using lot's of gas. However, is there any way of being sure the weld is being properly shielded.

I have watched demonstrations of the correct technique on UTube which I am carefully following. This is my first go at tig welding although I have considerable experience in straight forward oxy-acetylene welding.

Some of my early welds had a lot of pin holes and some slag formed on top of the weld similar to stick welding. I have scrapped these welds and I am starting all over again but want to avoid wasting time and materials as I have done up to now.

Your advice would certainly be appreciated as I getting very frustrated.

[mikecwik]

is the material super clean? down to the base metal and degreased? what filler rod are you using? double check the polarity earth clamp in+

contact tig starts seem to mess up the electrode if thats what youre using. i never understood how it does that since it happens way after the contact. some people use a copper start pad but it hasnt made much difference to me.

[Qwert66]

Yellow powder = presence of galvanization on the surface of the metal before welding. Requires better cleaning prior to welding. DO NOT BREATH ANY OF THESE FUMES IF YOU WANT TO LIVE.

[B_C]

Pictures would be helpful but it sounds like your dipping the tungsten (yellow stain) and not grinding it before welding again....It has to be clean. Also 7mm out of the cup is about 1//4 plus I think you will need to hold a tight clearance with that much sticking out with a STD cup.....( not gaslens) As mentioned galvanized metal won't give you the best results, so if your using galvanized sheet metal
you need to switch to a non- plated steel......Other that that I need pictures?

[kiamaian]

Thanks guys for all the help. You have given me some tips which I will try today and I will post again soon.

[kiamaian]

I tried again today taking great care to have the base metal very clean. I also reduced the amount the electrode was exposed. The weld was still not satisfactory so I got my oxy-acetylene equipment out and after grinding the metal back to scratch I started welding the old fashioned way.

It was immediately obvious that I have a severe pollution problem as when I started heating the joint I had a mini fireworks display with red sparks shooting upwards. I also noticed that when I formed a puddle of molten metal I could see pollutants floating on top. I let the joint cool down and applied some stainless steel flux which improved things but it was still not like welding good quality mild steel.

The cylinder I am trying to weld was galvanized many many years ago and the other metal is steel pipe but it is not genuine boiler tube.

It looks like the old case of the poor man paying twice. I could have saved money by buying better steel in the first place. Ugh!

In actual fact the tig welder was doing a good job in the circumstances. However, the pollutants were quickly making the electrodes deteriorate.

[kiamaian]

The plot thickens!

I have just welded a second joint using oxy-acetylene which I had not previously tried welding with TIG. It was quite easy to do and there was not the pollutants present as there was on the first joint.

All I can think of is that the first joint had remnants of tungsten present from the melt down of the electrodes I was using even though I had heavily ground the bad weld.

Fortunately, this is a hobby project and not a commercial project.

[mikecwik]

are you using a rod for tig or the ones you use for o/a? not sure if its the same there but here rg45 would be the o/a rod and er70s2 would be for tig.

[papasloan]

You dont want to use rg45 for tig welding. It does spark and leaves a crappy weld. Use er70 s2 or s6 for tig. I have used the er70s6 for gas wekding. it works fine if the metal is clean. oxy acet welding is more forgiving on cleanliness than tig is. Make sure its clean.
Also you dont want to weld galvanized or plated steel of any kind. It will give you the residue you say you are getting.
If you have to attach to anything galvanized you should try tig brazing rod ercusi. Like I said have to. Do not make a habit of it! The fumes are very toxic. Make sure you are well ventilated.
Your tungsten can be getting dirty from the rg45.
Clean the metal and make sure it is clean and not plated. Aluminized exhaust tubing will weld fine with tig or gas. Seems the alum just floats to the top of the weld bead. It doesnt seem to bother anything just looks a little strange when you run the bead.
I did the transition from gas to tig and tried using rg45 because it was here. Only took 1 time with tig then made sure rg45 only got used for gas welding.
Its like welding with dirty steel.
Like BC said make sure the metal is clean and not plated. and check to make sure you have the cables plugged in correctly. And you should be fine.
Keep the tungsten sharp and clean.

[kiamaian]

Hi,

I had a discussion with an employee of my local welding supplies shop and he asked me about the shielding gas that I am using and whether it was 100% argon.

On checking I found that I have been supplied with a gas that suits MIG welding which is largely argon but has a small percentage of oxygen.

Could this be the source of my problems? Namely rapid electrode deterioration, yellow staining around the finished weld and a form of slag on top of the weld and lots of pinholes which are revealed after wire brushing.

I can ring the gas supplier when they open tomorrow but I would like to know the answer before I start the discussion.

[B_C]

If you have Argon it will be just Argon......I have
Had bad batches of gas in the past
But nothing so bad that it gave the
Results you describe. Have you ever
Got good welds with the metal and
Set up you currently have? Again pictures
would be helpful.

[usmcpop]

You think maybe they gave you 98/2 Argon Oxygen mix for spray MIG welding? I would think that would make short work of the Tungsten, not to mention other ills.

[kiamaian]

The gas company replaced the cylinder today with another containing pure argon. This has solved all my problems and I am now getting clean welds that I am happy with. The gas that was wrongly supplied contained a small percentage of oxygen which may be required for MIG welding but is certainly wrong for TIG welding.

Thanks for all the responses and interest shown.

[Marksweldingams]

Well now I don't have to answer as I see you found your problem.
Yes if they use a co2 bottle or something else I've found them to be contaminated even with the correct sticker on them.
Good luck I love tig welding.