Hello I am fabricating a performance boat rudder from 17-4 ss. It is a machinded rectangular plate with a 1" round welded to it. The blade will have a notch milled to receive the round pivot shaft . The notch fully beveled. When fitup on a bench the perimeter will taped and the back side will be flooded with argon. Using 630 tig wire. Have welded much 304 and 316 but never 17-4. What would be best procedure as far as preheat ( if any) interpass heat etc. This weldment will be subsequently heat treated to 170,000 psi . Thanks in advance for the info. Nate