Weld test coupon fixture design for GTAW in Aluminum

[capntom62]

We are in need of certifying some more GTAW welders in Aluminum in the Aerospace industry, 1G position. There are a few schools of thought when it comes to fixture design. Some say have a copper backing bar that is grooved out with the largest acceptable root reinforcement with Argon back gassing holes. Others like myself, are saying a square groove that is deeper than the root reinforcement limits because the new guys need to learn how to control and cool the root to avoid excessive melt thru. Excessive root reinforcement on groove welds is our biggest turn back.

Any advise ?

 

[capntom62]

I was looking for more of what the practical shops due. AWS D17 does not cover fixture design.