Three-point bend testing of HVOF AMDRY 9954 coating on Ti-6Al-4V alloy

HVOF coating of AMDRY 9954 powders onto Ti-6Al-4V alloy is considered. Three-point bending tests are carried out to examine the tensile-shear response of the coating under the bending load. The study is extended to include the heat treatment of the workpieces after the coating process prior to three-point bending tests. The morphological and microstructural analyses are carried out using scanning electron microscopy (SEM). Finite element method (FEM) is introduced to simulate the bending situation and predict the stress distribution in the workpieces. It is found that coating with small porosity and voids is achieved. Elongated cracks are developed in the coating in the region of deflection of the workpiece during the bending tests. This, in turn, results in partial attachment of the coat onto the base material without complete peeling off from the substrate surface due to stress relaxation at coating interface. However, the coating with severe crack formation and total peeling off from the substrate surface are also observed, which is more pronounced for heat treated workpieces.