Abstract
The Bureau of Mines is investigating low-chromium alloy substitutes for type 304 stainless steel (type 304 ss). The purpose of the research is to reduce the chromium content in austenitic stainless steels used for corrosion-resistant applications. Nine fe-9cr-12ni alloys containing additions of 0 to 5 pct mo, 0 to 2 pct V, and 0 to 2 pct cu were selected for evaluation. All of the experimental alloys containing 5 pct mo and an alloy containing 2mo-2v-2cu possessed structure and tensile strengths similar to those of type 304 ss. Alloys containing 5mo-2v and 5mo-2v-2cu had acceptable welding properties as measured by the varestraint test. Alloys containing at least 2 pct mo had corrosion resistance comparable to that of type 304 ss in solutions of nitric acid, phosphoric acid, acetic acid, and citric acid. In chlorides, all the experimental alloys were susceptible to localized corrosion and stress corrosion cracking similar to that of type 304 ss. The corrosion properties were established by weight-loss tests, electrochemical polarization tests, and stress-corrosion cracking tests. An fe-9cr-12ni-5mo-2v alloy and an fe-9cr-12ni-5mo-2v-2cu alloy had a combination of welding properties, tensile properties, and corrosion resistance that were most comparable to those of 304 ss.
