Duplex Steel S 32304—A Low Cost and Corrosion-Resistant Alternative to the Austenite Containing Molybdenum

In Germany the “BAM-List – Requirements for Tanks for the Transport of Dangerous Goods” is the basis for substance-related prototype approvals for tank containers undertaken by the BAM - Federal Institute for Materials Re­search and Testing. Compatibility evaluations of selected metallic materials as well as of polymeric gasket and lining materials under the influence of approximately 7000 dangerous goods have been published in the BAM-List since 1989.

The duplex steel S 32304 was originally developed as substitute for the austenitic grades 316L and 316Ti. Due to its characteristic profile this steel was qualified for applications requiring high strength values at concomitant adequate corrosion resistance. Because of its lower content of the alloy elements nickel and molybdenum this duplex steel is a cost-efficient alternative to the molybdenum containing austenite. 

Only a limited number of corrosion test results of S 32304 under the influence of dangerous goods published in the BAM-List were available. Therefore test specimens of this steel were exposed to selected corrosive substances.

Due to the reduced alloy content a reduced corrosion resistance of the duplex steel S 32304 in acidic substances, such as formic acid, acetic acid and sulphuric acid, in comparison to the austenitic CrNiMo-steels was observed. Tests in an alkaline medium showed sufficient resistance.