Dr. Oliver Hatt

Research Associate for Manufacturing with Advanced Powder Processes (MAPP) at The University of Sheffield

After obtaining a First Class degree in Chemistry, I initially followed a mechanical engineering career working for the AMRC with Boeing before studying for my PhD at the University of Sheffield.

My research is centred on titanium alloy machining, particularly the interactions at the tool-workpiece interface which is underpinned by alloy and tool design. I employ high resolution electron microscopy techniques such as TEM and FIB as well as thermodynamic modelling with Thermo-Calc, DICTRA and TC-Prisma.

I am currently working on the design and development of new materials for gas turbines as part of the EPSRC ‘Designing alloys for resource efficiency (DARE) – a manufacturing approach’ partnership across the University of Sheffield, Imperial College London, Kings College London and the University of Cambridge as well as ten industrial partners, including: Timet, Rolls-Royce, Tata Steel and Siemens.

Current Research

Today the aerospace industry spends hundreds of millions of dollars on the machining of titanium alloy components.

And with increasing aircraft orders, there is pressure to machine at higher production rates and develop more machinable alloys (e.g. TIMETAL® 54M, TMETAL® 407) without compromising titanium’s excellent mechanical properties. Increasing the tool life by a factor of minutes can have a dramatic effect on machining cost. Unlike steels, the same tool grade is used for all titanium alloy types from alpha to beta rich, with the latter being more difficult to machine. Diffusion dominated crater wear is the primary tool wear phenomena which has yet to be fully understood. My current research investigates the application of a low cost diffusion couple technique which gives a strong indication of the complex reaction mechanisms occurring at the tool-chip interface during the machining of titanium alloys. These small scale tests have been validated with large scale dynamic machining trials and strong agreement has been observed. Such a testing regime can be incorporated into alloy design approaches to inform the industry e.g. TIMET and Rolls-Royce about the ‘machinability’ qualities at a much earlier stage before costly machining trials. Such a method will also aid tool manufacturers to tailor tool carbide grades as well as new coatings to specific alloy chemistries.