Influence of hot isostatic pressing on structure and properties of titanium cold-spray deposits

In this paper, an experimental study of the influence of capsule-free hot isostatic pressing (HIP) on the microstructure and tensile strength of cold-spray pure titanium deposits is considered. It is shown that hot isostatic pressing at 110 MPa and 1173 K significantly changes the microstructure of titanium cold-spray deposit. Total porosity was decreased from 4.3 to 2.2% due to elimination of small-scale porosity (pores with size less than 5 μm), whereas larger pores were not completely closed. Measured ultimate tensile strength (UTS) of as-sprayed and HIP-treated samples was 110 and 480 MPa, correspondingly. Increase of UTS is explained by material diffusion and microstructure changes during the HIP cycle. At the same time, ductility of the samples after HIP was only ~ 8% which is significantly lower than that for the bulk pure titanium.