Linking anisotropy with Fe₃C distribution in AISI 1045 steel

The anisotropy of the microstructure, thermal expansion behavior, corrosion resistance and magnetic properties of AISI 1045 steel was investigated. The distribution of Fe₃C lamellae in the investigation plane parallel to the radial directions of molds was observed to differ from that in the investigation plane perpendicular to the radial directions by transmission electron microscopy. The lattice constants a₀ of α-Fe deduced from the XRD patterns of samples prepared using a sand (S)-mold and cut parallel to the radial direction of the mold (S//) and using a metal (M)-mold and cut parallel to the radial direction (M//), the corrosion resistance measured using an electrochemical workstation, and the magnetic permeability obtained by vibrating sample magnetometry also indicated the existence of anisotropy in the tested samples. The anisotropic change of corrosion potential (E_corr), pitting potential (E_pit) and magnetic permeability (µ) of the samples was observed to depend on the orientation factor F₂₀₀ of α-Fe in the measured samples, which is controlled by the distribution of Fe₃C lamellae in the eutectoid structure.