Intensive Forming of Grade 5 Titanium Bars with Increased Performance for Aerospace Applications

摘要

The HDQT (High Deformation Quenching and Tempering) technology is an innovative intensive forming method which produces ultra-fine-grained microstructures e.g. for heavy duty components. Already having been applied successfully to enhancing the mechanical properties of conventional steels without modifying their chemical composition, the technology is now transferred to high strength materials such as Titanium alloys for aerospace applications. With a modified HDQT technology, high deformation degrees are realised in several incremental forming passes on a Grade 5 Titanium alloy Ti-6Al-4V. A final globulitic dual phase microstructure is adjusted by the repetitive incremental deformation of the initial material. Twisting of the grains during deformation is a characteristic feature of the forming process. The latter is believed to provide effective obstacles to the crack propagation within the component and thus increase its damage tolerance during service. The manufacturing of Ti-6Al-4V pre-forms for the following closed-die forging of turbine blades is studied as a possible application of the technology. The influence of the processing parameters on the resulting microstructure has been analysed in detail. Based on it, optimum process parameters have been identified. First results from the mechanical testing are presented and discussed in the context of potential application for aerospace components.