Creep deformation behavior of nano oxide dispersion strengthened Fe–18Cr ferritic steel

The objective of present work is to investigate the creep behavior of nano oxide dispersion strengthened Fe–18Cr ferritic steel (Fe–18Cr–3W–0.3Ti–0.35Y2O3) over a range of temperatures 923–1023 K and range of stresses 175–400 MPa. The analysis of creep data according to the power law equation suggests high apparent stress exponents (17–26) and high apparent activation energy (~690 kJ/mol). Microstructural analysis indicated that no change in the grain and nanoprecipitate size occurred in the sample crept at 973 K and 225 MPa after 2600 h. Transmission electron microscopy studies on crept samples revealed substantial dislocation activity in the grains and the interaction between dislocations and nanoprecipitates. Based on the analysis of results, dislocation detachment mechanism is identified as a creep mechanism in the present steel. Accordingly, the creep results are rationalized based on the dislocation detachment model and mechanical threshold stress model.