The Bureau of Mines conducted research on the partial replacement of chromium in stainless steel. The alloys examined contain 8 to 9 pct cr, 11 to 14 pct ni, and additions of up to 5 pct mo, 2 pct cu, and 2 pct V for corrosion-resistant applications and up to 5 pct si and 2 pct al for heat-resistant applications. Molybdenum additions enhanced the corrosion resistance to approach that of type 304 stainless steel (304ss) in phosphoric acid, nitric acid, citric acid, and acetic acid. Alloys with si and al additions had 800 deg. C oxidation resistance superior to that of type 304ss. The stress rupture resistance of the best si-al alloys was comparable to that of type 304ss. The alloys had tensile properties typical of austenitic or martensitic stainless steels, depending on their structures. They exhibited greater tendency to hot crack during welding than did type 304ss. Additional levels of ni, mn, or c may be needed to stabilize an austenitic structure in these substitutes. Additions such as mo, si, and al have potential to substitute for approximately one-half of the cr in stainless steels for many applications.
J. Mater. for Energy Syst., V. 7, No. 1, June 1985, PP. 75-81