N. Wain, X. Hao, R. Aswathanarayana Swamy, M. H. Loretto, X. Wu, University of Birmingham, Birmingham, United Kingdom
Beta titanium alloys are often used for structural components in the aerospace industry due to their high strength, obtained by ageing the metastable beta phase to precipitate fine, well-dispersed alpha particles. The recently-introduced alloy Ti‑5553 shows excellent tensile properties, along with a wider available processing window than previous beta alloys such as Ti‑10‑2‑3. However, the ideal combination of high strength and high toughness is still difficult to achieve due to the tendency of the alloy to form a brittle continuous alpha phase along grain and subgrain boundaries. This investigation shows the effects of changing different aspects of the ageing process on the resultant microstructure and properties of Ti‑5553 alloys, with particular emphasis on grain boundary alpha formation. The effect of added carbon, which is known to influence grain boundary precipitation in other beta titanium alloys, is also investigated. Results show that very small additions of carbon can strongly influence alpha precipitation and the consequent age hardening response. Aspects of the ageing process such as heating rate and the introduction of an intermediate dwell are also shown to be significant.
Summary: An investigation of the effects of ageing conditions and carbon content on the microstructure and properties of the beta titanium alloy Ti-5553. Results show that carbon, heating rate and intermediate dwell temperature can strongly influence alpha-phase precipitation.
