First TIG, not going so well!!

[paul r]

Hi,

Tried to TIG two scrap pieces of mild steel box section together 50x50x2.5..

Attached is the pic of an attempt at a butt weld. I used about 75 amps and 6lpm argon. 1.6mm rod and filler.

I also tried a fillet and couldnt get it to work. First attempt just stuck to one side and didnt touch the virtical piece. I went over it again with more filler and it just kind of bubbled up and made a mess!

In need of help i think!!

Paul.

 

[shenion]

Looks like the weld is contaminated with oil or mill scale.

TIG needs spotlessly cleaned metal. Grind down surface (flap disk works well) and clean inside/out with solvent (I use acetone, don't use brake cleaner.)

 

[paul r]

Looks like the weld is contaminated with oil or mill scale.

TIG needs spotlessly cleaned metal. Grind down surface (flap disk works well) and clean inside/out with solvent (I use acetone, don't use brake cleaner.)

I'll be honest and say i didnt bother to clean it as it was just a test!

Would that be the problem with the fillet too? how does it not being clean affect the weld?

Cheers,

Paul.

 

[shenion]

Look at the black pits in the weld, that is the impurities bubbling out.

Too low a gas flow will have similar effects, but tend to be on the surface and edges. Yours looks like it is coming from underneath.

I wire brush mine (SS brush on drill) and it seems to be enough. Most of mine is old steel, new stuff often has oil on it to keep from rusting.

 

[Wedg1e]

My usual rule-of-thumb would suggest you needed more like 90A for that wall thickness but it doesn't actually look too far off, other issues aside.

 

[paul r]

My usual rule-of-thumb would suggest you needed more like 90A for that wall thickness but it doesn't actually look too far off, other issues aside.

When I went upto 90a, it just blew holes in the steel.....

Paul.

 

[Shox Dr]

I'll be honest and say i didnt bother to clean it as it was just a test!

...and therein lies the problem, with 99% of people learning to weld, because "it's just a test" they think it doesn't require the preparation.

WRONG

Everything is in the preparation

 

[paul r]

...and therein lies the problem, with 99% of people learning to weld, because "it's just a test" they think it doesn't require the preparation.

WRONG

Everything is in the preparation

I'll get a flap disc from wickes on the way home and try again later I'll see if they do acetone too..

Cheers,

Paul.

 

[paul r]

Right,

Couple more pics. First one is another practice, second and third are welds on my bench. I ground the metal this time and cleaned with acetone. I couldnt grind the inside of the box section though as i couldnt get the grinder in there, so i just gave it a good wipe with acetone.

I think the first one(practice) was ok, appart from the little hole - I guess this is contamination from the back of the steel??

The second pic(my bench), I think is quite good? the start and end need a bit more practice, so any pointers on that would be good?

The third pic - There was a little hole as in the first picture. I tried to go over it again with some filler and it bubbled up and made it worse....is this contamination again? How can I avoid it?

Any comments?

Cheers,

Paul.

 

[shenion]

Still looks like oil. Have had engine crankcases that were real bad (aluminum).

Could have missed some spots or touched them with oily hands when handling. I notice they are only on the curved corners. It might possibly be pulling in air from the back, but usually that makes them pitted, not cratered.

Are you keeping the filler clean? Could be you dragged it on the oily parts. Keep it in the gas so it does not oxidize; one of my common mistakes.

I have had to grind a few back the bad spots and do again. The welds do look good. Looks like you have a consistent travel and filler speed.

 

[GeorgeB]

Couple more pics.

I'm impressed. If I can produce TIG welds like that after a couple of days I'll be amazed! You can't be going far wrong.

 

[paul r]

Still looks like oil. Have had engine crankcases that were real bad (aluminum).

Could have missed some spots or touched them with oily hands when handling. I notice they are only on the curved corners. It might possibly be pulling in air from the back, but usually that makes them pitted, not cratered.

Are you keeping the filler clean? Could be you dragged it on the oily parts. Keep it in the gas so it does not oxidize; one of my common mistakes.

I have had to grind a few back the bad spots and do again. The welds do look good. Looks like you have a consistent travel and filler speed.

thanks for the comments, very helpfull. I left the filler on the floor and then on top of some unclean metal - so I bet that's it? Also finding it difficult to keep the filler inside the stream of argon, but I guess that's just practice?

If it's pulling air in from the back, what's the solution? More gas flow? I'm using 7lpm at the moment.

Thanks for saying the welds look good! I'm really trying at it makes me feel like I'm getting somewhere!

Cheers,

Paul

 

[paul r]

I'm impressed. If I can produce TIG welds like that after a couple of days I'll be amazed! You can't be going far wrong.

If I can, then I'm sure anyone can! My hands aren't exactly steady! I do find it takes a lot of preparation and patience though. Where as with stick welding you just 'point and go' with no prep, but the welds aren't half as pretty!

Paul

 

[shenion]

Yes, I have grown to love stick. My MIG has sat idle most of this year. Stick/TIG for almost everything (and brazing with Oxy/propane.) Stick is great on stuff I'm too lazy to clean.

Increasing the gas flow might help when air is pulled from the back, it can make it worse (venturi effects.) Like I said, it looks like oil contamination, air is small pits.

Try again, I'm surprised you still have probs. I had some square tube that had lots of oil. So much, even MIG had problems.

Edit: did some TIG tonight:

Fusion weld (no filler) thick metal (brackets) to thin (trailer fender). Was hard to balance doing footpedal. Varied current higher on thick and less as moving to thin. Not real neat, but a good weld. I ground both pieces. What is not clear, is there is a big crater in the top right. Got the exact same on the mirror part. I had ground paint off, top bottom and fender. Must have missed the side at the tip. Probably just a small spec of paint.

Does not take much

 

[justin]

im new to welding just learning the basics in college but when on their tigs the gas flow needs to be on about 10 lpm to get good results on similar thickness metals

 

[langy]

I would of thought 90 amp to, I remember when i learn't and i was using less amps and moving slowly, I would try 90 amps and move a bit quicker

My usual rule-of-thumb would suggest you needed more like 90A for that wall thickness but it doesn't actually look too far off, other issues aside.

 

[Syafi]

cleaning is the part that is the easiest to do yet its is very tempting not to clean. end result with clean material is very easy to weld plus the weld look beautiful. without cleaning it is faster to start welding but took much longer to finish because well, we will have to grind those weld or go through the weld again and start and stop much too often compared with clean material.