I am in need of some suggestions on a weld procedure.
Part: Forged horizontal turbine shaft (hydro), chemistry matches AISI 1040. (C=.39%)

Customer specifying ASME code to be applied to repair for procedure qualification.

Since 1040 does not have a P#, I understand the need to qualify a procedure.

Weld work is crack repair around 3-1/2" dia. dowel pin holes in the coupling flange of the shaft. Small cracks 1/4" up to 1/2" long, depth uncertain, but not likely very deep. Cause of cracks also uncertain. (also waiting on hardness testing results).

Will likely GTAW most of the excavations, may have to SMAW one large spaulded out area about 3" dia. x 1/4" deep. Need some help with preheat, and spec. for GTAW filler rod. Lots of adjacent machined surfaces and
I am trying to avoid excessive preheat to try and prevent any flange or shaft distortion.
Thanks!