That makes sense, Slowrotor. I've been stressing up 12mm plate recently - without FEA optimisation we still see failures! Just make sure there are no initiators for weld failure, and that joints are prepared/dressed for maximum weld strength. Counldn't find Enstrom details, but i bet they still don't overstress the welds.
http://www.b-domke.de/AviationImages/Rotorhead.html
I just assumed that all heli steel bits were either forged, high pressure cast, or machined.
Mart