Creep–structural relationship in steel alloy 800 H at 900–1000°C

Abstract

The creep properties of the 32Ni–20Cr steel alloy 800 H have been investigated in the temperature range 900–1000°C. The results show that the creep behaviour is characterized by various irregularities. Structural analyses performed for selected creep conditions have revealed that significant structural instabilities become relevant during the creep process. As a result of the continuous ripening of the carbide precipitates the density of carbide pinned dislocations, which are assumed to provide an important contribution to strength, decreases as the creep process advances. In correlation with creep crack formation, a nitriding effect can occur during long term testing in air which is accompanied by an increase of the creep resistance.