Effect of Thermal Diffusion Temperature on Coating Structure and Properties of Electro-Galvanized C72D2 Steel Wire

Electroplating process was used to galvanize the surface of C72D2 steel wire, and the mass of the coating per unit area was 45 g·m^-2. The thermal diffusion treatment was carried out at different temperatures (450-550℃), and the galvanized steel wire was drawn into monofilament by wet drawing process. The effects of thermal diffusion temperature on the structure of the coating, the tensile strength and rotating bending fatigue performance of monofilament were studied. By comparing with hot dip galvanized steel wire and monofilament, the best electro-galvanized thermal diffusion process was optimized. The results show that with increasing thermal diffusion temperature, the Zn-Fe alloy phase in the electro-galvanized steel wire coating increased, and the Fe-rich phase increased, while the Zn-rich phase decreased. When the temperature was above 520℃, the Fe₃Zn₁₀ brittle phase was formed, and cracks appeared in the coating. Compared with the hot dip galvanized monofilament, the electro-galvanized monofilament treated by thermal diffusion at 480℃ had higher tensile strength, less coating loss, and similar fatigue life, which met the requirements for the use of monofilament for elevator traction belt wire ropes.