Process parameter optimization and EBSD analysis of Ni60A-25% WC laser cladding

In this research work, the parameters of the preset powder feeding laser cladding process of Ni60A-25% tungsten carbide (WC) powder were optimized by using the response surface methodology of the central composite design. The dilution rate eta and unit effective area phi of the laser cladding layer were considered as the response. Based on the factors and levels in the design matrix, the Ni60A-25% WC powder was fused on the 42CrMo alloy structural steel substrate with the laser cladding process to form a high-microhardness cladding layer. In this work, the microstructural characterization and crystal orientation analysis of the laser cladding layer obtained from the optimal process parameters were performed by using a Field Emission Scanning Electron Microscope (FE-SEM) and the Electron Backscatter Diffraction (EBSD) technique. The microhardness of the specimen processed with the optimal process parameters was evaluated using a Vickers microhardness tester. The results show the order of influence of four laser cladding process parameters on the dilution rate eta and unit effective area phi. The developed mathematical models for the dilution and the unit effective area were validated. The errors between the experimentally obtained dilution rate eta and unit effective area phi and predicted values were within acceptable limits. The EBSD analysis revealed that there was no meritocratic orientation of the substrate, while the laser cladding layer showed a pronounced meritocratic orientation. A large amount of martensite was produced within the coating after the laser cladding, resulting in a significant increase in the microhardness compared with the substrate. The microhardness test results were consistent with the microstructure morphology.

Automated summary

In this research work, the preset powder feeding laser cladding process of Ni60A-25% tungsten carbide powder was optimized using response surface methodology. The microhardness of the laser cladding layer was significantly increased compared with the substrate, and the mathematical models for the dilution and unit effective area were successfully validated. The EBSD analysis showed a pronounced meritocratic orientation in the laser cladding layer.