Influence of Welding Currents on Microstructure and Performances of Ni-Nb Composite Surfacing Layers

The Ni-based alloy surfacing layers with Nb powders were prepared on the surface of Z2CN18-10 stainless steel by plasma surfacing welding technology. The microstructure, hardness and wear resistance of the surfacing layers were analyzed. The influence of welding currents on the microstructure and performances of the surfacing layers was studied. The results show that when the welding current is 140 A, NbC particles can be precipitated well in the surfacing layer, and the surfacing layer has good wear resistance. When the welding current is 110 A, the hardness of the surfacing layer can reach 509 HV0.3. However, the surfacing layer is not well formed and the wear resistance is also the worst. When the welding current increases to 170 A, the hardness of the surfacing layer is significantly reduced, and the wear resistance is also reduced compared to that under 140 A.