Influence of WC content on microstructure and wear resistance of Fe-based plasma surfacing layers

Objective The purpose was to improve wear resistance of roll and reduce the loss, so as to extend service life of roll. Methods Plasma surfacing technology was adopted to prepare Fe-based plasma surfacing layers with different WC content on the surface of Cr5 steel substrate. Phase, microstructure, hardness and wear resistance of the surfacing layer were tested. Results The results showed that with the increase of WC content, main phases of the surfacing layer were α-Fe, M₇C₃, M₂₃C₆, W₂C, Fe₃W₃C and γ-Fe, and microstructure was composed of cellular crystal, dendrite, interdendrite solid solution, equiaxed crystal and unmelted WC particles. With the increase of WC content (wt.%), grain size became smaller and microstructure became more uniform. However, when WC content exceeded 40%, defects such as pores and cracks appeared in the surfacing layer, which reduced performance of the surfacing layer. With the increase of WC content, macroscopic hardness at the top of the surfacing layer increased first and then decreased, while wear quantity decreased first and then increased. Conclusion When WC content was 30 %, microstructure was relatively fine and uniform, the highest hardness is 64 HRC, the minimum weight loss was 3.33 mg. Wear mechanism was abrasive wear and slight fatigue spalling wear, and wear resistance was the best.