Effect of Post-Deposition Thermal Treatments on Tensile Properties of Cold Sprayed Ti6Al4V

Abstract

This study aims at investigating the effect of various post-deposition thermal treatments on improving tensile properties of cold spray (CS) deposited titanium alloy Ti6Al4V. Dogbone-shaped tensile specimens were designed considering two application scenarios: ‘fully CS’ specimens, and ‘CS repair’ specimens. For both specimen types, tests were carried out in four conditions: (i) as-deposited (AD), and after three different thermal treatments, i.e., (ii) solution treatment and ageing (STA), (iii) hot isostatic pressing (HIP), and (iv) HIP followed by STA (HIP + STA). Complementary to tensile testing, characterisation of CS deposited material was also carried out in terms of microstructure and hardness. The STA process resulted in the highest improvement in ultimate tensile strength by more than 200%, reaching 868 MPa for ‘fully CS’ and 951 MPa for ‘CS repair’ specimens. However, no appreciable improvement in elongation at failure was achieved, highest being 1.2% for ‘fully CS’ after STA, and 4.3% for ‘CS repair’ after HIP. In addition to experimental investigation, a comprehensive collection of data from the open literature on the effect of various thermal treatments on improving the tensile properties of CS Ti6Al4V deposits is reported and discussed.