The influence of Si content upon the corrosion resistance of Fe-12Cr and Fe-12Cr-12Ni alloys exposed in a reducing/sulphidising atmosphere at 450°C

摘要

Many materials programmes have been directed at assisting in the selection of the most economic materials having sufficient durability for components operating with metal temperatures of 300 to 550°C. In highly reducing/sulphidising gases, low-alloy steels corrode too fast to permit their long-term use at greater than about 250°C. The use of coatings or higher-alloy materials may introduce unacceptable cost penalties. There is an obvious cost incentive, therefore, in improving the performance of less expensive alloys by elemental additions which ensure the formation of an adherent protective scale. Results are presented here of a study concerned with the corrosion of some 12%Cr "model" alloys with Si additions of 1.3 to 4% exposed in a non-equilibrated CO-rich gas, of the type found in a dry-feed entrained slagging gasifier, at 450°C. Significant improvements in corrosion resistance of the higher Si alloys are discussed and compared with results on selected, more expensive commercial alloys.