Residual Stress Analysis of Cold Spray Coatings Sprayed at Angles Using Through-thickness Neutron Diffraction Measurement

This work deals with the comparison of the morphology of aluminum 6061 splats cold sprayed at various angles between computational finite element modeling predictions and experimental observations. Computational modeling of single-splats sprayed at various angles predicted that the highest shear stresses would occur at impact angle of 60-65°, while the highest interfacial equivalent plastic strains would be observed at 50° and both would decrease as the spray angle increases. The amount of interfacial-bonded material was also observed to decrease as the spray angle increases. The computational model was correlated with experimental data from neutron diffraction and x-ray diffraction methods, and experimental tensile adhesive strength test results. From both neutron and x-ray diffraction through-coating measurements, it was also observed that the residual stress profile of the coatings would be increasingly more negative from the coating surface toward the substrate interface, before becoming less negative from that point on. The data also suggested that the coating residual stresses are largely biaxial although there were suggestions of anisotropy for coatings sprayed at oblique angles of 50° and 70°, which was also predicted by the simulation model.