Effect of initial microstructure on the creep behavior of TMCP EH36 and SM490C steels

Two steels, TMCP EH36 and SM490C, were prepared with the same composition but different rolling processes. The equiaxed grain of TMCP EH36 steel was produced by thermo-mechanical control rolling (TMCP) with an accelerated cooling process. The banded structure of SM490C steel was produced using a conventional hot rolling process. After creep, the results show that the apparent activation energy and apparent stress exponent in the band structure of SM490C steel are much higher than that in the equiaxed grain of TMCP EH36 steel. The creep stress exponent value from the threshold stress, σ0, concept in the dispersion strengthening mechanism can explain how the second phase distribution and morphology have an important effect on the creep behavior in this study.