Application of heat-resistant titanium-based compressor disk with dual structure

Near-α alloy, Ti5.8Al4.0Sn3.5Zr2.8Mo0.7Nb0.4Si0.06C, has been developed as a forging material for high temperature structural use in aircraft turbine engines. This alloy is characterized by the addition of a large amount of Mo which improves the strength without reducing the ductility. This heat-resistant titanium-based alloy has great potential for use in jet engine applications up to 550 °C. We have considered the optimization of each manufacturing process on the production scale for compressor disk applications. The present conventional forged titanium-based disks have a single structure to optimize the balance of fatigue and creep properties. In general, it is widely known that a bi-modal structure which consists of primary α grains in a matrix of transformed β phase containing acicular α phase has the advantage of improving the fatigue strength, whereas a fully transformed β structure has the advantage of improving the creep strength. So, we investigated the possibility of producing disks with dual structure, that is the bore section and the rim section consist of a bi-modal structure and a transformed β structure respectively, for application to compressor disks of jet engines. The mechanical properties of the transition regions between the sections in the dual-structure disk were also investigated in this study.