Effect of substrate surface condition on fatigue behavior of cold sprayed Ti6A14V coatings

Ti6AI4V coatings were deposited on Ti6A14V substrates by using a high pressure cold spray system. Before deposition, the substrate surfaces were prepared with four different surface preparation methods, namely, grinding, milling, sand blasting and water-jet cutting. The fatigue behavior of the coated specimens was studied with three point-bending-fatigue test. The fracture characteristics of the specimens were observed by using scanning electron microscopy. The surface roughness and its effect on the crack initiation and propagation in the coatings were also investigated. The results indicated that the fracture mode of the coated samples was interface cracking. At two different stress levels such as 420 and 360 MPa, the samples with the coatings deposited on the ground surfaces survived the longest fatigue life before failure, while the samples with the coatings deposited on the water jet cut surfaces survived the shortest fatigue life. It was clearly shown that the fatigue strength of the cold sprayed Ti6AI4V coatings was strongly affected by the both spraying and substrate surface preparation conditions. (C) 2016 Elsevier B.V. All rights reserved.