β21S titanium alloy heat treatment development and improvement

Wilson, Tony (2017). β21S titanium alloy heat treatment development and improvement Bachelor's Thesis, School of Mechanical and Mining Engineering, The University of Queensland. doi:10.14264/uql.2018.280

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Author Wilson, Tony
Thesis Title β21S titanium alloy heat treatment development and improvement
School, Centre or Institute School of Mechanical and Mining Engineering
Institution The University of Queensland
DOI 10.14264/uql.2018.280
Publication date 2017-10-27
Thesis type Bachelor's Thesis
Open Access Status Other
Supervisor Michael Bermingham
Total pages 62
Language eng
Subjects 09 Engineering
Formatted 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 after 72 hours, which corresponds well with the in-service temperature and time of failure. This thesis aims to discover a heat treatment that can withstand this temperature and resist hardening, whilst maintaining the ductility.

Tensile tests were applied to four sets of properties: as-received or virgin material, industry-use condition material, industry-use then aged material, and finally aged then industry-use material, where the aging condition was the previously found 679°C for 8 hours. What was concluded was that the as-received samples had significantly better properties in terms of ductility as expected, and the peak-hardness condition material had the worst properties. The material that performed the best, besides the virgin material, were the specimens that were optimally heat-treated at 679°C for 8 hours first, and then underwent peaked industry condition of 400°C for 72 hours.

Whilst a conclusion was reached in this regard, further testing involving more samples, more temperature and time variations, and potentially different variations of heat treatment applications than the ones completed, would allow for a more thorough analysis and result.
Keyword MECH4500

 
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Created: Wed, 13 Dec 2017, 13:49:45 EST by Rose Clements on behalf of School of Mechanical and Mining Engineering