β21S titanium alloy heat treatment development and improvement

Abstract

The study focusses on investigating the heat treatment of β21S titanium alloy in aerospace applications. The aircraft engine components made of this alloy are failing during service; believed to be associated with a lack of ductility due to the hardening of the alloy during use. To accurately analyse the alloy, the manufacturer recommendations on the aging process was to be utilised, where a range was given in the material properties sheet (Appendix A). Four conditions were treated in this range to find the most effective heat treatment; 566°C for 8 hours, 566°C for 16 hours, 679°C for 8 hours, and 679°C for 16 hours. After the heat treatments were applied, and appropriate preparation was completed, hardness tests on each set of heat treatments were completed. The heat treatment with the lowest hardness, and therefore the best ductility, was the condition of 679°C for 8 hours. To further investigate the heat treatments, the peak hardness condition for the material was used to represent the industry condition that was being simulated in the testing process. Previous work has found that the alloy is at its peak hardness at 400°C