Multi-objective Optimization of Laser Welds with Mixed WC/Co/Ni Experiments Using Simplex-centroid Design

Abstract

This work involves the preparation of WC/Co/Ni blends using different mixing ratios to form Co/Ni/WC composite-based coatings by laser cladding. The effect of each component and their mixtures on the mechanical properties was evaluated using a mixture design approach. The morphologies and microstructures of the laser clads were characterized using a scanning electron microscope and X-ray diffraction techniques. Cracking behavior and fracture based on residual stresses are explored. In addition, the mathematical models between the three-component mixtures and the mechanical properties of the laser clad were established. The results showed that the welds containing 50 % WC-50 % Ni alloys were successfully deposited by laser cladding with favorable mechanical properties. These welds reduced the remarkable fracture crack activities and did not cause delamination in the laser clads. An increase in WC content significantly enhances wear resistance and microhardness, except for the crack susceptibilities in all mixtures. Additionally, when increased Co/Ni on WC, the reduction of adhesive wear is more significant than that of abrasive wear. Wear resistance is improved by the high content of WC particles in the laser-clad joints. Based on the mixture models, better mixed ratios for the blends that were developed using a multi-objective superimposed optimization technique make these blended materials promising candidates and can ensure the quality of laser clads. The findings from this study will greatly contribute to optimizing the blend ratio of the three-ingredient mixture based on mixture design to enhance structural evolution and mechanical properties, and also obtain better quality laser-clad coatings.

Keywords

• laser cladding
• mixture design
• microstructural evolution and mechanical properties
• wear resistance