Evaluation of Possible Test Methods For Qualifying Lean Duplex Stainless Steel

摘要

In the past five years the use of lean duplex stainless steels such as LDX 2101? (UNS S32101) has grown substantially. The lean grades are now used in a wide array of industry sectors including chemical processing, pulp and paper, oil & gas, transportation, desalination, and building/architecture. An issue that is continually raised about the lean duplex stainless steels is the lack of a standard qualification test to verify acceptable property levels. Existing standard corrosion tests such as those outlined in ASTM A 262, A 923, and G 48 are either not applicable for duplex stainless steels or are too aggressive to evaluate lean duplex stainless steels. Because of this Outokumpu has investigated the use of metallography, impact tests, and corrosion tests for evaluating the S32101 grade. This paper presents results from impact tests, electrochemical cyclic polarization tests, and immersion tests in ferric chloride solutions inhibited with NaNO3. Results from solution-annealed samples are compared with samples that were heat treated to produce undesirable phases such as nitrides, carbides, and sigma phase. Test results are correlated with aging times and suggestions on possible standard test methods are presented.