Residual Stress Depth Distributions in Cold Gas Sprayed Titanium Coatings—Effect of Nozzle Traverse Speed and Substrate Material

Abstract As a solid-state material deposition technique with unique capabilities concerning attainable properties, cold gas spraying (CGS) is gaining increasing attraction in application fields of functional coatings, additive manufacturing, and local component repair. In the present study, CGS of grade 1 titanium was investigated in view of application as a repair method of damaged aerospace components. The current study focuses mainly on analysing residual stresses developed in the deposited material and substrate by means of the incremental hole-drilling method. This work aimed to investigate the influence of local thermal contributions on residual stresses by focusing on nozzle traverse speed and the type of substrate material. The results indicate that local residual stresses depend on the thermal mismatch between coating and substrate materials, the substrate material properties, and the nozzle traverse speeds. For instance, the residual stresses in grade 1 titanium coatings were observed to be tensile in case of coating and substrate exhibiting similar thermal properties, and compressive (thermal stress dominant) in case of coating material having significantly lower coefficient of thermal expansion than the substrate. Additionally, it was observed that the residual stresses shifted further toward the tensile residual stress regime under increased surface temperature by using decreased nozzle traverse speeds.