Thermally activated plastic deformation behavior of nano oxide dispersion strengthened Fe-18Cr steel: Experiments and analysis

Strengthening Mechanisms in Nano Oxide Dispersion-Strengthened Fe-18Cr Ferritic Steel at Different Temperatures

“…It varied from 0.78 to 0.81 in the temperature range of 873 K to 1173 K. More discussion on K r values is presented in our earlier paper. [44] Earlier, Kim et al [34] also found a similar range of values (0.75 to 0.78) in the temperature range of 873 -1273 K in n-ODS-14Cr steel. Accordingly, the strength due to nanoprecipitates above transition temperature estimated from dislocation detachment model (Eq.…”

“…The variation of yield strength (obtained at a range of temperatures from RT to 1473 K and a strain rate of 10 À2 s À1 ) normalized by temperature-dependent shear modulus (G T (GPa) = 89.5[1 À 0.84((T-300)/T M )] [43] ) with temperature is presented as a master plot in Figure 5. The yield strength data in the temperature range from RT to 1173 K correspond to the hot extruded material (present study) and those in the temperature range from 1273 K to 1473 K correspond to the upset forged material (refer our earlier paper [44] ). To get an overall insight of the deformation mechanisms governing the deformation in n-ODS-18Cr steel, the entire data are presented in the master plot.…”

“…(ii) In regimes II (773 K to 973 K) and III (973 K to 1473 K), the normalized yield strength decreases with increasing temperature indicating that multiple thermal activation mechanisms have started playing a substantial role resulting in the yield strength becoming lower than the athermal values. More interestingly, the strength obtained above 1273 K is mostly due to one dominant mechanism, i.e., Rö sler and Arzt mechanism [41] (see Section III-E-B-B) and the contributions of other strengthening mechanisms are regarded as insignificant (more details are given in our earlier paper [44] ).…”