The Bureau of Mines has developed a low-chromium stainless steel with low-temperature corrosion resistance in acidic media and elevated temperature oxidation resistance in air. Two alloys, nominally containing Fe-8Cr-16Ni-5Si-1Cu and 0 or 1 Mo, were evaluated for their potential as low-Cr (8% Cr) substitutes for conventional (18% Cr) stainless steel. Corrosion resistance was electrochemically evaluated in 1 N H2SO4, 25% HNO3, 86% H3PO4, and 40% citric acid, and by mass-loss measurements in 1 N H2SO4, 25% HNO3, 86% H3PO4, glacial acetic and 40% citric acids, and distilled water. Static oxidation tests were performed at 700 and 800°C. Corrosion resistance for both alloys was equivalent to type 304 (UNS S30400) stainless steel in the 86% H3PO4, glacial acetic and 40% citric acids, and distilled water; poorer in 25% HNO3 and better in 1 N H2SO4. The oxidation resistance for both alloys was slightly poorer than type 304 SS at 700°C and slightly better at 800°C.

Subject
Acids, Water, Oxidation resistance, Corrosion resistant alloys, Stainless alloys, Corrosion rate, Microstructure, Molybdenum alloys, Copper alloys, Corrosion resistance, Stainless steel, Alloys, Oxidation
Keywords:
chromium, corrosion behavior diagram, high-temperature oxidation, low Cr, mineral acids
NACE International
1992
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