Meaningful Tests for the Quality of Superduplex Stainless Steels (SDSS)

Abstract The strong detrimental influence on both toughness and corrosion resistance of intermetallic particles (IMP) in the microstructure of duplex stainless steels is well known. Toughness and corrosion testing along with microstructural examination of samples has been used as a collective to determine either “freedom from” or “acceptable” levels of deleterious phases in the microstructure of these steels. However, users of duplex alloys continue to report problems. This paper considers how meaningful current test regimes and acceptance levels are and how they correlate with each other. The value of ferritiscope testing to detect intermetallic particles is also considered. Overall, the paper proposes more meaningful test acceptance levels and procedures along with, supplementary ferritiscope testing to optimise the capability of this group of tests to detect deleterious phases.