Microstructural evolution and residual stress behavior for optimization of laser-mixed WC(Co,Ni) Clads

Zhou, Hong (2018) Microstructural evolution and residual stress behavior for optimization of laser-mixed WC(Co,Ni) Clads. Favourable review or citation

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Abstract or Summary

This work addresses the preparation of a ternary mixture with tungsten carbide(WC) cobalt(Co) and nickel(Ni) alloys to form ceramic-metal composite coatings using laser cladding for additive manufacturing. This coating was investigated using mixture design to evaluate the influence of various blend ratios on the residual stress behaviors of the clads. Residual stress behaviors are evaluated using an XRD diffractometer method, and the crack morphology, microstructural evolution and phase compositions of the laser clads are characterized by Scanning Electron Microscopy. As a result of the laser cladding welds, a homogeneous microstructure is obtained by adding Co/Ni alloys to WC in the molten zones, so that gas porosity, microcracks and intermetallic defects in the single WC are visible. The WC(Co,Ni) ternary mixture exhibits higher residual stress than that of the Co/Ni binary mixture or the WC/Ni binary mixture, except for the WC/Co binary mixture, in which there is marked improvement of crack susceptibility in the ternary blends. Single WC or Co or Ni mixtures illustrate the high sensitivity of residual stress behaviors. Additionally, the cracks pass through WC particles at 100% WC, rather than around the WC particles, and the cracks mostly propagate along the eutectic phases at 50%Co-50%WC. Furthermore, a reduced special quadratic model in the mixture design exhibits excellent fit, and there is satisfactory agreement between the predicted and the experimental values of the residual stresses for these laser clads. This study optimizes the proportion of the three ingredients and ensures appropriate residual stress for laser clads, demonstrating that enhanced structural evolution is possible using laser cladding.

Item Type:Favourable review or citation
Keywords that describe the item:Microstructural evolution, Tungsten carbide, Mixture, Simplex-centroid design, Scanning electronic microscope and residual stress behavior
Subjects:T Technology > T Technology (General)
Divisions:Schools > Centre for Engineering and Industrial Design
ID Code:6140
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Deposited On:12 Sep 2018 21:43
Last Modified:18 Dec 2018 07:39

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