High temperature tensile properties of metallic materials exposed to a sulfuric acid decomposition gas environment

Corrosion tests using plate and U-bend specimens of Alloy 800H, Hastelloy X R and Inconel 600 were conducted in sulfuric acid decomposition environment of thermochemical hydrogen production process. Then tensile tests using ba r specimens after corrosion were carried out to evaluate the effect of the corrosion on high-temperature tensile properties. Corrosion in sulfuric aci d decomposition environment proceeds through formation of surface corrosion film and grain boundary penetration consisting of internal oxidation and s ulfidation. Corrosion cracking and acceleration of corrosion under stress w ere not observed in the corrosion tests at 850 degreesC in this environment . The values of 0.2% proof stress after corrosion are above 80% compared wi th those of solution-treated alloys and values of ultimate tensile strength after corrosion are above 90%. In addition, little decrease in high-temper ature ductility by corrosion is observed.