Microstructure and fatigue crack growth of EA4T steel in laser cladding remanufacturing

EA4T steel has been used widely in railway axles. Considering the failure behavior of railway axles and other solving methods, laser cladding remanufacturing was used for repairing the railway axles. The microstructure and fatigue fracture mechanism of EA4T steel in laser cladding remanufacturing were investigated by optical microscope (OM), scanning electron microscope (SEM) and X-ray diffraction (XRD). The fatigue life and fatigue crack growth were measured by three-point bending experiments. The microstructure of cladding layers was composed of columnar crystal and fine dendrites, and the main phases of cladding layers were γ and Fe2B shown by XRD results, which lead to the highest micro-hardness value in the cladding layer. The da/dN-ΔK curves and fracture morphologies indicate that the cladding layers could delay the fatigue crack initiation and improve the fatigue life of EA4T steel.