TIG welding - why does the ripple happen?

[Wing Commander]

Have a bit of DIY experience with MIG but no knowledge of TIG at all. Why does the end result look rippled?

Such as here

Is it deliberate and, if so, why?

Or is it because of the process itself?

[grim_d]

Because they have a separate filler rod which they push into the weld, a bit like gas welding, each ripple is where they moved position.

Having the "row of nickels" on your tig weld is the ideal scenario I hear.

Have a look at videos on youtube!

[Wing Commander]

grim_d said:

Having the "row of nickels" on your tig weld is the ideal scenario I hear.

OK, but why? Is it a strength thing? Will it help limit a tear if a crack in the weld appears?

[grim_d]

That's one I don't know! I can only assume it gives the strongest join.

[grim_d]

Scratch that.

It seems that the "ripple" welds are mostly cosmetic!

http://www.instructables.com/id/How-to-Weld-TIG/st...

[GAjon]

It's the weld profile of the moulton weld pool solidifiying as the joint is welded along. Imagine a wave lapping on a shore but instead of ebbing back it solidifies and the next wave laps up on that and so on and so forth.

[freecar]

Gas welding does the same, it comes from allowing a weld pool to build and then adding material as it is needed. Your weld pool essentially goes from shallow to deep to shallow to deep, the ripples are where the filler material has become one with the parent material. If you have a non ripply weld on top of the material then you have insufficient penetration. So I suppose people look for the "roll of nickels" to indicate sufficient penetration and technique.