Assessment of new fatigue capable titanium alloys for aerospace applications

钛合金用于大型和中小型民用燃气轮机的高性能旋转部件。对于风扇叶片和风扇盘等应用，需要具有增强强度和疲劳性能的钛合金。劳斯莱斯目前主要使用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项目的一部分，一些商业开发和R-R IP合金正在考虑中。这些合金是RR11、S23、Ti542、Ti407、Ti412和Titan 27。喷气发动机的最新发展提出了对Ti-6Al-4V替代材料的需求，这种材料既要提高平均疲劳性能、损伤容限和冷态疲劳不敏感性，又要与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。Ti407和Ti412被称为贫铝合金，因为它们的铝含量比Ti-6Al-4V等普通钛合金低得多。它们的发展是为了提高破坏时的延展性，从而提高能量吸收能力。Ti542是Ti64的替代品，对冷态不那么敏感。S23是一种具有较强疲劳性能的高强度钛合金，采用粉末冶金方法开发。最后，钛27是Ti64的改进型，具有优异的冷热加工性。本研究的主要目的是发展对羽绒合金如何响应机械载荷的基本理解。设想工作将在加工和优化所选材料上进行，以研究化学变化对机械性能的影响，使用小规模熔体和加工路线，并将其可扩展性用于生产尺寸部件。在课程中，学生将学习高级显微技术的核心技能，如显微结构和纹理表征、基本的钛冶金和热机械加工。该学生将深入了解用于航空航天领域的合金的发展路径，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.