The Centre for Doctoral Training in Advanced Metallic Systems is a partnership between industry partners and the Universities of Sheffield and Manchester and the I-Form Advanced Manufacturing Centre, Dublin. CDT students undertake a doctorate with an in-depth technical and professional skills training across a structured 4-year programme. For more information on our cohort training programme and our impact from our doctoral research projects with industry please visit www.metallicscdt.co.uk.
This project is based at the University of Sheffield with collaboration from Boeing. In addition to the complexity of form and reduction of material waste that additive manufacturing (AM) offers, there is a clear evidence that a well-executed AM process can develop material microstructures that can enhance the in-service behavior of many engineering alloys. Stainless steels and titanium are some of the alloys to exhibit enhanced mechanical properties when made by AM over the same materials processed by conventional methods. Other engineering alloys such as Aluminium can also be readily controlled in-process using methods learned from conventional metallurgy and through thermal management of AM process. Controlling structure, form and function for engineering alloys processed by AM is also essential to reduce secondary operations such as stress relief, HIP or heat treatment.
However, there are challenges in exerting this degree of process control. Presently AM systems operate using “fixed” processing parameters. The in-process monitoring, where performed, tends to focus on simple detection of major defects and the movement of components during the build as a result of thermally induced stress. This is a significant step forward, but also raises the question: Would it not be better to spot the conditions under which these failure modes occur and take action to avoid them happening in the first place? Within the MAPP EPSRC Future Manufacturing Hub (Sheffield, Oxford, Cambridge, Manchester, Leeds and Imperial College London) we are seeking to develop such an approach. In this PhD we will examine the potential for managing and manipulating processing conditions to better control engineering alloy microstructures in-situ, employing new modes of laser operation to generate desired microstructures and properties on demand, directly from the process.
This PhD will combine In-process and In-situ characterization and measurements (High speed, High Resolution Thermal imaging, hyper-spectral imaging, mass spectrometry etc.) with process modelling (analytical and computational) to look first at the control of structure and stress in simple geometries but swiftly progressing to more complex geometrical forms representative of those present in “real” products. The objective of the project is to develop methodology for producing tailored and localized microstructures to achieve required properties of the AM parts. This also includes in-line management of process to control the conditions for defect-free and desired structure.
The researcher would be part of a large, multidisciplinary team at the University of Sheffield, and integrated into the wider MAPP Hub and network. The program is clearly dynamic but experimentally we would certainly cover the following aspects:
o Enhanced melt vector definition – in real time to change solidification conditions locally o Melt pool and background temperature – in process sensors and at Harwell synchrotron
o Relating thermal history to defects, microstructure, strain, etc.
o Selective heating of built layers for defect ‘repair’ o The use of AM lasers to perform in-situ ‘heat treatments’ and advanced scanning strategies
All of these approaches would be developed with a view to solving real production problems and would focus on alloys of interest to Boeing, such as newly designed AM alloys under development in other UK based projects. For more information on the project, please contact Iain Todd ([Email Address Removed]).
Application close date is 25 th April 2021.
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