You may choose either, low-nickel austenitic stainless steel filler metal such as 209, 219, or 240 OR duplex ferritic-austenitic stainless filler metal such as 2209 to match the strength of 304L/316L and resistance to Ch SCC. Since 304 and 316 grade contains Ni in the range of 8 – 12 % Nickel.

See Copson Curve (1959); it was from a study of austenitic stainless steels, it shows worst SCC performance at 6% Ni or so, and improving performance as the Ni increases in austenitic Stainless Steels.

Fig. 1 Copson curve for SCC in Stainless Steels, Shaded region represents nickel range of many austenitic Stainless Steels. Source (Ref:-1)

Ref: – D J Kotecki / J.C Lippod Welding Metallurgy of SS, Wiley Pub. Pg. 206-207.