Effects of grains‘ morphology on strengthening mechanisms in ODM401 14Cr ODS steel at high temperatures

Abstract

The effect of grain orientation on the mechanical behavior of the 14Cr ODS steel (ODM401) at temperatures 400–800 °C is analyzed. The tensile and stress relaxation tests are performed on tensile specimens with grain orientation parallel and perpendicular to the extrusion direction. The strengthening mechanisms are analyzed in terms of the internal and thermal stress component, dislocation glide and climb and grain boundary creep. Models of strengthening mechanisms are used for evaluation of their intensity for a given temperature, grain orientation and macroscopic plastic strain level (0.001, 0.01, 0.025). Both grain orientations provide similar strengthening up to 600 °C. The grain orientation parallel to the extrusion direction provides higher strength at temperatures 700–800 °C due to the reduced grain boundary creep and dislocations annihilation at grain boundaries.