High-Temperature Stress-Rupture Properties of a Ferritic Steel for Solid Oxide Fuel Cell Interconnect

Abstract

The high-temperature stress-rupture properties of a ferritic steel (Crofer 22 H) for use as an interconnect material in planar solid oxide fuel cells are investigated. Constant-load creep tests are carried out at 650 to 800oC. For a given applied stress, the creep rupture time is decreased with an increase in temperature. The creep rupture time is well correlated with the applied stress by a simple power law for each testing temperature. The fitted power-law curves of 650-750oC look somewhat parallel to each other while the curve of 800oC is steeper than the others. A greater reduction of creep strength in the long-life region is present at 800oC. Larson-Miller relationship also does well in correlating the creep rupture time with applied stress and temperature. Fractographic and microstructural observations indicate such a significant reduction of creep strength in the long-life region at 800oC can be partially attributed to a precipitate coarsening effect.