Microstructure and Mechanical and Impact Behaviors of WC-Particle-Reinforced Nickel-Based Alloy Surfacing Layers at Evaluated Temperatures

A WC-particle-reinforced nickel-based alloy surfacing layer was fabricated on 42CrMo ultra-high-strength steel. The microstructure and the mechanical and impact-damage behaviors of the surfacing layers at the evaluated temperatures were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and the Vickers hardness tester. Results showed that these WC particles gradually changed from elongated and crisscross needle-like phases to blocks with the increase in impact temperature. Numerous carbide phases (e.g., (Cr,Ni,Fe)(23)C-6) and ?-Ni phases were formed in the substrate matrix. The surfacing layer showed a typical brittle fracture, and the impact energy decreased with the increase in temperature. Moreover, the surfacing layer showed a clear quasi-cleavage fracture morphology without dimples after a 600 degrees C impact test but exhibited a mixture of dimple fractures and cleavage fractures after the 200 degrees C and 400 degrees C impact tests. The Vickers fracture toughness test showed that the average hardness of the surfacing layer after a 600 degrees C impact test was 383 HV1.0, which is about 0.8 times that after the 200 degrees C impact test. In addition, the WC particles in the surfacing layer after the 600 degrees C impact test showed the highest fracture toughness, but the corresponding Ni40A binder phase possessed the lowest fracture toughness.

Automated summary

A WC-particle-reinforced nickel-based alloy surfacing layer was fabricated on 42CrMo ultra-high-strength steel. The microstructure and mechanical properties of the surfacing layers were investigated at different impact temperatures. Results showed that the WC particles changed in morphology with increasing temperature and the surfacing layer exhibited lower impact energy and fracture toughness at higher temperatures.