Dull looking welds...?

[longrod]

Just wondering if anyone can help me with this?
I'm new to this TIG thing but have been giving it a few goes on scrap 316 (see attached).

The welds look rather dark and dull, not bright and shiny and not at all like what they should do. Is this something easy to solve (wrong argon setting, wrong gas etc), or am I just a lousy welder?
Machine is a Cebora 1665, current was a bout 70m amps, tubing is 1/2" NB with about a 2mm sidewall thickness. Shielding gas is pure Argon at about 17cfh
The wall is standard housebrick...

Thanks in advance for any advice, and well done on a great forum.

 

[bert]

have you tried bevelling the tube at the welds so you can lower the amps and still get full penetration. i use about 30-35amps on 1.5mm tube thats been bevelled and have to move quite fast.

Argon is the right shielding gas but it looks like your just getting it too hot.

 

[StickNtig]

Make sure what your welding to and the consumable are both clean, make sure your getting good gas coverage.

We use a degreaser to clean materials and consumables etc

 

[longrod]

Thanks for those, I'll knock the amps down a bit, I was working to the 40 amps per millimetre rule but it I must admit the metal looked very red indeed and seemed to be burning through a lot.
I have some degreaser so will try the cleaning thing too.
Thanks again.

 

[hotrodder]

Arc length, arc length, arc length... http://www.mig-welding.co.uk/forum/showthread.php?t=7862 On small diameter tube/pipe the constantly changing 'angles of attack' for the torch and wire make this quite difficult.

Fillets/partial pen welds aside stainless really needs to be purged- the back of the weld will oxidise heavily (coked/sugared welds) if it's not protected from O2 in the atmosphere. When new/learning heat control is usually a bit lacking... if/when welding too hot* these oxides will be pulled through the puddle and result in a sluggish/manky weldpool which'll make life more difficult and add to the grey dullness of the finished weld

Check out the welding tutorials at the top of this page if you haven't already. The reason they suggest beginning with flat sheet that's a min of 2 or 3mm thick is that it makes life easier for both the above reasons amongst others.

Another good resource here that also has a pic of a coked/sugared stainless weld... http://www.millerwelds.com/resources/articles/common-TIG-GTAW-welding-problems-visual-guide-graphic If you go to the resources tab at the top of that page and click on 'improving your skills' you'll find the TIG resources section which is mostly really good stuff- don't take the welding amperage calculator as gospel, it's often miles out and their idea of a short arc length is a bit sloppy although kinda understandable as it's aimed at beginners

* too hot doesn't necessarily mean too many amps, it can be the reult of moving too slowly as amperage is related to travel speed.

 

[backpurge]

As has been said above, everything is getting too hot, bit hard to tell from the photos but it looks as if the weld bead is quite wide. On this thickness material there is no need to weave, you need to keep the bead as small as possible. Aall your kit looks OK, yes, there are far better gases for welding stainless but you should be able to get good results with argon.
The key is don't get dis-heartened, just keep practising, you will find it all falls into place

 

[langy]

I would use a 1mm Tungsten and 1mm rod for that job, set your gas around 6, Can't suggest amps as i use a pedal.

 

[Tig man aza]

Maybe try a gas lense I noticed a big difference on stainless when i started using them common setup is 1.6mm gas lense with a No.8 ceramic