Effects of post-deposition processing on static and cyclic performance of cold sprayed 6061 aluminum alloy

Abstract

The impact of various post-deposition treatments on the static and cyclic properties of cold sprayed 6061 aluminum alloy was investigated. Microstructural and mechanical properties of helium- and nitrogen-sprayed deposits in their as-sprayed condition were evaluated. To enhance the mechanical properties of nitrogen-sprayed deposits, different heat treatment procedures were applied, including conventional heat treatment and hot isostatic pressing (HIP). The influence of processing temperature was also studied by processing the deposits at regular and elevated temperatures. Specimens were tested in both annealed and solution-aged conditions. The interparticle bond quality of the deposits after various post-deposition processes was assessed using SEM and TEM. The grain structure of the deposits was examined using EBSD. Mechanical properties including hardness, tensile properties, and fatigue behavior were also investigated for different conditions. While helium-sprayed deposits exhibited mechanical performance close to the wrought material, nitrogen-sprayed deposits were non-load-bearing in their as-sprayed condition. However, post-deposition processes proved highly effective in enhancing the mechanical properties of these deposits. Specifically, HIPing at elevated temperature improved tensile strength and fatigue strength of the deposits to 90 % and 75 % of the wrought material, respectively, placing it in the same range as cast aluminum alloys. Additionally, the study demonstrates that quantifying bonding regions between particles enables the prediction of fatigue life through the application of Continuum Damage Mechanics (CDM).