Study on microstructure and properties of Fe-based amorphous composite coating by high-speed laser cladding

Fe-Co-B-Si-Nb amorphous coatings were deposited on 45 medium carbon steel under different scanning speeds by high-speed laser cladding technology. The results showed that the surface roughness of the coating became lower and the surface of the coating became smoother with the increase in scanning speed. In addition, the residual tensile stress and the thermal expansion coefficient decreased with the increase in the scanning speed. When the scanning speed was 80.38 m/min, the residual tensile stress was 106.13 ± 24.03 MPa. The residual stress was reduced by more than 50% compared with the scanning speed of 37.68 m/min. The XRD and TEM observation results of the coating at the scanning speed of 80.38 m/min showed a large volume fraction of amorphous phase and some crystalline dendrites. Under the scanning speed of 80.38 m/min, the cooling rate at the top of the coating could reach 1.08 × 105 °C/s, which greatly increased the amorphous formation ability. The hardness and wear resistance properties of the coating were also tested and analyzed. Better performance of the coatings was obtained when the scanning speed was higher.