TIG Dimples

[johngargano]

I do a great deal of TIG welding with mild steel (1018). While I have mastered the beginning and main part of the bead, my termination points have either dimples or craters. How does one terminate the TIG bead with a smooth finish? I have tried lowering the amperage, yanking the torch away quickly, making smaller and smaller circles, etc.

How do you masters do it?
Thanks

John G.

 

[MikeMilburn]

Hi John,
It's been a while since I've done any amount of tig work, but I used to break the arc, wait a second or so to allow the puddle to cool, reestablish the arc for a time long enought to fill the crater and lower the amperage as I broke the arc.
One thing to remember, do not move the torch away from the molten puddle or you'll have a burnt crater, and watch your post flow gas times. High frequency on start was a great help too, saved a lot of sharpening....Mike

 

[welder123]

Hello John I am a nuclear pipe welder, we mostly weld carbon steel chrome and stainless. When I am not using a foot peddle I will move side to side quickly so that my puddle solidifies and I will break the arc in a forward motion and file away the point of termination. When I am using a foot peddle I pretty much do as Mike has described. I will lower my current and oscilate side to side quickly so that the puddle solidifies and I am not breaking the arc in a large molten puddle. If your power source will allow you to lower the current all the way to termination by using the foot puddle or other current control device this should fully eliminate any craters. Hope this helps!

 

[mcprofusion]

Hi Johnny

I weld for UA United Association for Plumbers and Pipefitters. I would have to agree with welder123, with his technique. We call it "Walking the Cup"...by rolling your torch side to side in a tighter weave pattern in a forward motion, filing away the point of termination. I use this technique for most of all SS Steels and especially for Manual SS Tube Fusion welding.

 

[mcprofusion]

Another note...dimples..i call them fish eyes. Especially in GTAW of Piping, it is imperative that the eye is properly terminated. A fish eye can penetrate deep into the material, causing a through thickness pin-hole.