Bioinspired fibrous microstructure breaks strength and toughness trade-off in plain carbon steel

Warm rolling at eight temperatures was conducted on two mixed ferrite-pearlite initial microstructures in order to develop strong but tough plain steel. The obtained wood-like fibrous microstructure in AISI 1045 plain steel breaks the strength and toughness trade-off dilemma. After rolling at 500 °C, the tensile strength reaches 1020 MPa, and the impact toughness is as high as 120 J. Intensive α-fiber (<110>//RD) and η-fiber (<100>//RD) textures, as well as necklace-like fine carbide, were developed in the fibrous microstructure. With increasing rolling temperature, the tensile strength and impact toughness decreased due to the reduced texture intensity and the increased carbide size. The high strength of fibrous steels is mainly originated from the dispersion and dislocation strengthening, while the impact toughness is controlled by the carbide size and the occurrence of delamination mechanism.