Microstructure and fatigue behavior of cold spray coated A15052

The effect of cold spray coating in inducing residual stresses in the substrate and its effect on delaying crack initiation under cyclic loading have been studied on A15052 alloy specimens. Different sets of A15052 specimens have been coated with pure A1 and A17075 feedstock powder, using a low-pressure cold spray coating technique. Some sets of specimens were grit blasted (GB) before coating. The microstructural evolution of the substrate after coating and the fatigue behavior of the coated structure have been studied. In order to obtain the fatigue S-N diagram for each set, as-received and coated specimens with and without preceding GB treatment have been tested in a load-controlled condition. X-ray diffraction has been used to measure the residual stresses both in the deposited materials and the substrates. The results are discussed to highlight the effect of this emerging surface treatment on the characteristics of the treated material. Compressive residual stresses, which led to appreciable increase in the fatigue life, have been observed in all the coated sets. The results indicate that the fatigue strength was significantly improved up to 30% in the case of A17075 coatings. The results show a strong dependency of the fatigue strength on the deposited material and the spray parameters. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.