Welding 17-4ph to grade 316 1

I'd go with Alloy 600 (Inconel) or something close in a Ni base filler metal. The thermal exp. will match the 17-4 side fairly well. Preheat as much as you can.

Also, keep the entire weld area *real* clean.

The "Inconel" weld fillers referred to would be alloy 82 wire (ERNiCr-3) or 182 covered electrodes (ENiCrFe-3) and will more or less match the expansion coefficient of the 17-4. Important if the thing is to operate hot,say 500F or so. Shield GMAW welds with argon or argon helium mix, do not use argon-oxygen & neverever use 75Ar 25CO2 on any stainless or nickel alloy.
You may also make this joint with the 316L weld fillers.
H1150 is one of the best heat treated conditions for welding. Preheat 200-300F suggested for restrained welds, or for heavy sections, about 4" or greater.

James Kelly

Excellent reply from CalvinKelly....covered all aspects thoroughly.

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Thanks very much guys.

When welding dissimilar materials like these, determine which material governs the end use and service life of the weld. Should the strength requirement of the 17-4 govern or that of the 316? Should the weld match the corrosion resistance of the 316? Should the coefficient of expansion match that of the 316? If the 17-4 high strength governs, ERNiCr-3 or similar nickel base alloy filler metals are recommended. If the 316 governs, ER/E 309-Mo type filler metals are recommended.