Low cycle fatigue properties of 8Cr–2WVTa ferritic steel at elevated temperatures

The effects of test temperature and tension holding on the fatigue properties of reduced activation ferritic/martensitic 8Cr–2WVTa (F-82H) steel were investigated by conducting low cycle fatigue tests at temperatures ranging from RT to 650°C under the axial strain-controlled condition with strains ranging from 0.5% to 2.0%. Fatigue life data were formulated as strain-life equations. A large reduction in the fatigue life was recognized at temperatures above 600°C. Softening without showing a saturated region was observed in the fatigue softening curves at temperatures above 600°C. Tension holding during fatigue tests reduced the fatigue life at 400°C, 500°C and 600°C. The microstructural examination showed that the large softening during cycle was associated with carbide (M23C6) coarsening and Laves phase (Fe2W) precipitation at 600°C.