Low cycle fatigue behaviour study of a nano precipitate strengthened ferrite-bainite 780 steel

•Low cyclic fatigue behaviour of a nano precipitate strengthened ferrite bainite steel was studied.•The dislocation structure formed in the ferritic grain during cyclic loading determined the fatigue response of the material.•Strain accumulation at ferrite-bainite interface in the form of deformation bands led to hardening of the interface resulting in crack deflection.•Although the nano precipitates influenced the dislocation structure formation during cyclic loading, they did not significantly affect the fatigue response of the steel due their low number density and non-uniform distribution.