Tig questions

Date 11-03-2011 14:38

I know that contaminating the tip of the tungsten while welding is bad, but exactly why?

Where's a good place to learn more about stainless steel?

At the end of the weld it's always that ugly grey color, the rest of the weld is rainbow colored but right when I break off the weld it's discolored. I've tried holding the torch in place after I've broken the arc to allow argon to run over it, but it has no effect. How do I get the end of the weldment to look like the rest of the weld?

By Superflux (****)

Date 11-03-2011 15:05

First and foremost, it will "spit" pieces of tungsten into the puddle and make a really ugly white spot on the x-ray.
Second, it makes a blob on the tip and reduces arc control.
Dig through this forum and you will find all you ever needed to know and more.

Sounds like you are getting too hot/too slow of travel speed. Do you have an amp control? A thumb wheel or foot pedal? Sounds like you also might need to work on how to terminate properly. You need to let the puddle cool by slowly backing off the heat (amps). Sometimes the work needs to cool off before continuing to weld the next pass.

By defaced (**)

Date 11-03-2011 15:51

To add to what Superflux has said, a contaminated tungsten will often change the shape of the arc which can really screw with the puddle.

If the end of you weld is at the edge of a part, say like you butt welded two sheets together and the end of the weld is at the end of that seam, there's nothing there to help hold the gas in place. The gas is just falling off the edge of the plate and not doing you much good. That gray color is an oxide that can complicate additional passes if you were doing a multipass weld. Adding "dummy" material to help dam the shielding gas in is a good practice, both with manual and automated TIG. At my station I keep a stash of randomly sides steel blocks and plate stock that I've acquired to help contain shielding gas.