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Indexed by:期刊论文

Date of Publication:2018-11-01

Journal:JOURNAL OF IRON AND STEEL RESEARCH INTERNATIONAL

Included Journals:SCIE

Volume:25

Issue:11

Page Number:1149-1155

ISSN No.:1006-706X

Key Words:Ultra supercriticality; Hot corrosion; Sulfidation; Chloridation

Abstract:Hot corrosion rates of Super 304H austenitic stainless steelpre-coated inNa(2)SO(4)-25%NaCl mixture salt film in air at 650 degrees C and 750 degrees C have been investigated by corrosion kinetics curves. The corrosion products are examined by means of X-ray diffraction and scanning electron microscopy coupled with energy-dispersive spectrometer, and electron probe micro-analyzer to analyze the scale structure and element distribution of the cross section. The results indicate that the kinetics curves are similar and display parabolic growth, and the mass gain obviously increases with the increasing temperature. A two-layer oxide scale composed of Fe oxides containing CuFe2O4 and Cr2O3 forms on the surface of the alloy and easily exfoliates with extending corrosion time or with improving corrosion temperature. Moreover, a corrosion-affected zone with micropores and micro-cracks appears beneath the oxide scale. It is concluded that the selective oxidation occurs and a protective oxide scale forms at the early corrosion stage. The melt salts destroy the integrity of the oxide scale and accelerate hot corrosion of the alloy by the cyclical oxidation-chlorination during the further corrosion processing. In addition, internal sulfidation also contributes to the corrosion of the alloy.