Three-point bend testing of HVOF Inconel 625 coating: FEM simulation and experimental investigation

HVOF spraying of Inconel 625 powders on mild steel sheets is carried out. Three-point bending tests are carried out to examine the mechanical properties of the coating. Stress fields developed during the tests are simulated using Finite Element Method (FEM). ANSYS package is used to predict the stress field. Three- and two-dimensional modeling of the coating and substrate material are considered and the predictions of load–displacement characteristics are compared with the experimental results. Since two-dimensional predictions agree well with the experimental data, two-dimensional model is employed in the simulations. It is found that stress level exceeds the yielding limit of the substrate material at tensile surface of the substrate material and coating. Consequently, crack initiation and propagation at coating and substrate material interface occur. In addition, splats with high oxygen content are responsible for crack initiation in the surface region of the coating.