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Tig Welding penetration is affected by the angle of the tungsten grind.
There are several charts in text books and on web sites that depict the penetration profile caused by different grind angles of tungsten electrodes.
I like to see things for myself so I tested 3 very different angles on pieces of 2% lanthanated electrodes ...all 3/32" (2.4mm).
I let the piece cool completely in between beads and kept the arc gap the same for all three beads.
Travel speed as constant too on a welding turntable.
I cut the beads all the same distance from the start point and polished and etched using a stainless steel heat tint removal solution.