Correlation of Microstructure and Properties of Cold Gas Sprayed INCONEL 718 Coatings

Abstract

In the cold gas spray process, deposition of particles takes place through intensive plastic deformation upon impact in a solid state at temperatures well below their melting point. The high particle impact velocities and corresponding peening effects can lead to high compressive residual stresses in cold spray coatings. This can be advantageous with regard to mechanical properties as fatigue life and hence, cold spray is an ideal process for repair applications. In this study, INCONEL 718 particles were cold sprayed by using nitrogen as propellant gas. The deposited coatings with different thicknesses were characterized using electron microscopy techniques to study grain refinement and precipitates in the coating. In addition, depth-resolved residual stress measurements have been performed by the incremental hole drilling method. The residual stress depth profiles in the coatings indicate compressive residual stresses of several hundred MPa which are hardly influenced by the coating thickness. In addition, large compressive stress levels are found in surface-near regions of the substrate due to the grit blasting process. Furthermore, a post-heat treatment analysis was performed to investigate its influence on residual stresses and bonding strength. These findings are used to develop a consistent explanation of the dependence of strength values on thickness.

Evaluation of Inconel 718 Metallic Powder to Optimize the Reuse of Powder and to Improve the Performance and Sustainability of the Laser Powder Bed Fusion (LPBF) Process

“…This does not exclude their presence, but if they were present, they were in a very small amount. The XRD results for the powder in all conditions, as well as hardness and microscopic results discussed earlier, indicate typical microstructure of Inconel 718 powder, i.e., solid solution of γ phase with dendritic microsegregation, similar to that found in other studies [ 46 , 53 ]. This confirms the lack of powders’ thermal degradation, i.e., precipitation of additional phases, as all powder states are characterized by the same results.…”

Metal Knitting: A New Strategy for Cold Gas Spray Additive Manufacturing

“…The literature presents the application of CS for AM for a large number of materials, highlighting the components made from 316L stainless steel [ 10 , 11 , 12 , 13 , 14 ], Cu alloys [ 15 , 16 , 17 ], and Ti alloys [ 18 , 19 , 20 , 21 ], but not limited to them since Al alloys [ 21 , 22 , 23 , 24 ], Ni superalloys [ 25 , 26 ], maraging steel [ 27 , 28 , 29 ], and many others have also been studied. Moreover, these CSAM components have interested different sectors, such as aerospace, automotive, energy, medical, and marine sectors, among others [ 8 , 30 ].…”

Comparative Microstructural Study of Cold Sprayed Coatings Using Pure Aluminum and Aluminum Alloy Powders

“…The grain boundaries, coating boundaries, and inter-particle boundaries became visible in the as-fabricated stage via the EBSD characterization as shown in Figure 3a,b. The boundaries between grains are more pronounced than that at the grain boundaries, implying that the inter-particle grain boundary is the weak position after high-speed deposition [15]. Moreover, it can be seen that the microstructure exhibits obvious anisotropic microstructural features with different sections.…”