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.