TIG welds are porous, anyone know why?

[pryantcc]

Subject says it all really. When I'm welding, I can see the weld foaming & obviously when it cools the bubbles make it porous. Does anyone know what causes this?

[TWOTENS]

On MIG welds it is usually a sign that your shielding gas has run out, or you've forgotten to turn it on. The resultant weld is not as strong as it should be.

[pryantcc]

On MIG welds it is usually a sign that your shielding gas has run out, or you've forgotten to turn it on. The resultant weld is not as strong as it should be.

The bottle is low, so this might be the problem. Thanks for your answer!

[m.thaddeus]

Hello There
Obviously something is interfering with the weld pool. Most likely is either too much or too little gas. I would imagine that if you can use a Tig then you know about cleaning the metal. A lot of modern Steel sheet comes with a fine Zinc based coating which shouldn't cause a problem, a few years back a fine layer of oil was the norm and this would have.

If the weld is dry and crust - and very hard then that suggests low gas and therefore a lot of oxides. A gassy bubbly weld which grinds off in the normal manner would suggest too much gas - causing gas bubbles in the weld itself.

A glassy weld suggest some foreign material has been incorporated into the molten steel.

~Hope this helps Martin