High Temperature Sulphidation Behavior of Fe20Cr6Al-Y,Hf Steel
The high temperature corrosion behavior of Fe20Cr6Al-Y,Hf steel was studied in the range of temperature 800-1000oC in H2/H2S atmospheres at pS2=10-2 ,10-3 and 10-4 Pa sulphur vapor pressures. Kinetics depend on the temperature and sulphur vapor pressure. After 24 hours the whole specimen was practically consumed because the samples were 0,06 cm thick. Morphology of the scales have been performed by SEM techniques. Phase and chemical composition have been studied by EDX and XRD techniques. It was found that scale formed on Fe20Cr6Al-Y,Hf alloy was built with porosity sulphides layer. EDX analysis of the scale surface show that the any aluminum, hafnium and yttrium sulfides were found in the formed scale layer, however small amounts of Al2S3 was detected in scale/steel interface. Also internal sulphidation was observed. A phase analysis of the formed scale revealed that it is composed mainly of an FeS, Fe7S8 phases and CrS, Cr5S6. Result were compared with data obtained on the pure Fe and Cr samples.
Pierre Steinmetz, Ian G. Wright, Alain Galerie, Daniel Monceau and Stéphane Mathieu
M. Homa and Z. Żurek, "High Temperature Sulphidation Behavior of Fe20Cr6Al-Y,Hf Steel", Materials Science Forum, Vols. 595-598, pp. 763-768, 2008