Creep-fatigue interaction in a bimodal 12Cr-ODS steel

•Creep-fatigue interaction in a bimodal ferritic 12Cr-ODS steel was studied.•Symmetrical loop became asymmetrical upon introducing hold-time at either peak tensile or compressive strain.•Hold-time introduction resulted in a pronounced microstructural evolution.•Extensive precipitation/coarsening of Laves phase is associated with intergranular cracking and lower cyclic life under hold-time waveforms.•To avail ODS benefits to the maximum, secondary phase (Laves) coarsening has to be suppressed.