Long-Term Creep Performance of Ferritic SOC Interconnect Steel

ABSTRACT: Crofer^® 22 H is a well-known commercial ferritic stainless steel for the construction of SOC interconnect plates. Its performance under creep loading conditions in the temperature range from 700 to 800 °C was evaluated against a pre-commercial trial steel to signify the impact of thermomechanical treatment history on long-term creep response. While the commercial grade prevailed in solution treated, i.e., low dislocation density, state, the trial steel was put into creep service in a deformed, i.e., high dislocation density, condition. Dislocations do play a major role in the early stages of the nucleation of strengthening Laves phase precipitates, and for this reason, sensitively impact the creep response of the materials in the primary stage of creep, which even affects the following (limited) secondary stage and especially the transition into the creep life dominating tertiary creep stage.