Experimental and Simulation Investigation of Through Thickness Residual Stress in HVOF-Deposited WC- 10Co- 4Cr Coating

Application of WC-10Co-4Cr coating deposited by High Velocity Oxygen Fuel (HVOF) has been widely developed for its high wear and corrosion resistance. The residual stresses created during the coating deposition process greatly effects the wear resistance and the adherence of coating to the substrate. In this study, the residual stress of coating was determined by the X-ray diffraction (XRD) technique using sin2 method and finite element method(FEM). In the experimental evaluation, the chemical layer removal process was used to measure the through thickness residual stress. In the finite element method, the impingement of the WC-10Co-4Cr particle on substrate was studied. Afterwards, the results from the impingement analysis are subsequently utilized as an input data in thermomechanical model to develop the residual stress of as-sprayed coating. The results showed that there was a good agreement between the experimental and simulation results. Final surface residual stress of WC-10Co-4Cr coating was compressive. The value of residual stress was increased with the greater thickness of coating. These compressive stresses reached to maximum compressive stress at the coating-substrate interface. Simulation results showed that the distribution of stress in the coating, except for the edges of the sample, was uniform. Residual stress on the edge of the sample had a tensile stress concentration in the interface of the coating and substrate which was prone to cracks, separations and defects of coating.