Assessment of new fatigue capable titanium alloys for aerospace applications

钛合金用于大型和小型/中型民用燃气轮机的高性能旋转部件。对于诸如风扇叶片和风扇盘的应用，需要具有增强的强度和疲劳性能的钛合金。罗尔斯·罗伊斯目前主要使用Ti-6Al-4V用于350 ℃以下的应用，目前正在开发新的钛合金。作为ATI资助的BETA计划的一部分，正在考虑一些商业开发和R-R IP合金。这些合金是RR 11、S23、Ti 542、Ti 407、Ti 412和Titan 27。喷气发动机的最新发展提出了对具有改进的范围平均疲劳性能的Ti-6Al-4V的替代物的需求，损伤容限和冷驻留疲劳不敏感性，同时对其他钛合金具有良好的可焊性，并且在焊后热处理后必须保持其性能。被称为贫铝合金，因为它们具有比普通钛合金如Ti-6Al-4V低得多的铝含量。它们已经被开发用于增强失效时的延展性，从而增强能量吸收能力。Timet开发了Ti 542，作为Ti64的替代品，对冷保时间不太敏感。S23是通过粉末冶金途径开发的高强度钛合金，可显示出增强的疲劳性能。最后，Ti 27是Ti 64合金的改进型，具有优良的冷加工性和热加工性。本研究的主要目的是从根本上了解下选合金对机械载荷的响应。预计将对下选材料进行加工和优化，以研究使用小规模熔体和加工路线的化学变化对机械性能及其生产尺寸组件的可扩展性。在该计划中，学生将发展先进显微镜的核心技能，如微观结构和纹理表征，基础钛冶金和热机械加工。学生将深入了解用于航空航天领域的合金的发展道路，并与劳斯莱斯的工程师密切合作。

Titanium alloys are used in high performance rotating components for both large and small/medium civil gas turbines. For applications such as fan blades and fan discs, titanium alloys with enhanced strength and fatigue performance are required. Rolls-Royce currently utilises mainly Ti-6Al-4V for applications under 350C with new titanium alloys currently under development. As part of the ATI funded BETA program a number of commercially developed and R-R IP alloys are being considered. These alloys are RR11, S23, Ti542, Ti407, Ti412 and Titan 27.Latest developments on jet engines have raised the need for an alternative to Ti-6Al-4V with improved Range-mean fatigue performance, damage tolerance and cold dwell fatigue insensitivity while having good weldability to other titanium alloys and whose properties must be maintained after post welding heat treatment.Ti407 and Ti412 are known as lean aluminium alloys as they have much lower aluminium contents than common titanium alloys such as Ti-6Al-4V. They have been developed to enhance ductility at failure and hence energy absorption capability. Ti542 has been developed by Timet to be an alternative to Ti64 that is less sensitive to cold dwell. S23 has been developed via powder metallurgy route as a high strength titanium alloy may show enhanced fatigue performance. Finally, Titan27 has been developed as an improved Ti64 with excellent cold and hot workability.The primary purpose of this investigation is to develop fundamental understanding of how the down selected alloys respond to mechanical loading.It is envisaged that work would be carried out on the processing and optimization on the down selected materials to investigate the effect of chemistry variation using small scale melts and processing routes on the mechanical properties and its scalability to production size components.During the programme, the student will develop core skills in advanced microscopy, such as microstructural and texture characterisation, fundamental titanium metallurgy and thermomechanical processing. The student will develop an insight into the development path of alloys for usage in the aerospace sector and work closely with engineers at Rolls-Royce.