| Behavior of a Duplex Stainless Steel in H2SO4 + NaCl Environments. (1998) | |||||||||
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| The aim of this paper is to study the effect of chlorides in diluted sulfuric acid upon the uniform corrosion resistance of a nitrogen containing duplex stainless steel grade UNS S32550 (alloy 255); base metal and TIG welds were tested in various chloride and sulfuric acid mixtures at 70C; the corrosion behavior of two austenitic grades (UNS S31603 and UNS N08904) was compared to the duplex one; the superiority of the alpha/gamma structure is evidenced in several mixtures where the austenitic grades suffer uniform corrosion; nevertheless, in mixtures containing high sulfuric acid and chloride contents, a selective corrosion of the ferrite phase can occur; such a phenomenon was studied by potentiokinetic polarization tests and microstructure examination; we proposed an isocorrosion diagram in order to underline mixtures in which the duplex alloy 225 (welds and base metal) can be used safely. | |||||||||
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