Development of hybrid advanced manufacturing FAST-forge route for next generation aerospace components

Over recent years, researchers at The University of Sheffield have developed a hybrid solid-state processing route that converts titanium alloy powder into fully dense parts in two steps. Step 1 exploits the rapid sintering process - field-assisted sintering technology (FAST) to consolidate a range of titanium powder and particulates. FAST is different from conventional sintering methods as a current flows through the powder to achieve a Joule heating effect instead of using an external heat source. The team have demonstrated the consolidation of powders such as PREP, HDH, GA and machined swarf of a range of titanium alloy chemistries. The process produces densities comparable to hot isostatic pressing (HIP), however the advantages of FAST include consolidation times of up to 1 hour (as opposed to 4 hours in HIPing) and shaped preforms without the need for canning. Step 2; researchers at Sheffield have exploited the benefits of FAST to be an intermediate process for a subsequent one step forging stage to provide enhanced mechanical properties. FAST-forge is now being exploited for small to medium sized titanium alloy landing gear components.
The benefits of FAST as a solid state diffusion bonding technique for powder have recently been realised (known as FAST-DB). Rolls-Royce titanium alloy and nickel superalloy powders have been successfully bonded using such a solid state technique. Potentially FAST-DB can be developed into a manufacturing route that can provide components with multi-alloy regions, for example to enhance creep and fatigue resistance in key subcomponent regions, ultimately increasing the life of aerospace components. The aim of this EngD is to exploit and further understand the characteristics of the FAST-DB and FAST-forge for aerospace alloy powders. The aim is to use ThermoCalc, DEFORM and COMSOL software to produce predictive models for industrial scale FAST derived components. An example of a key demonstrator component could be a compressor blade where different titanium alloys may be used for the aerofoil and dovetail.

The project aligns with the large scale equipment earmarked for the Henry Royce Institute and objectives of the EPSRC Future Manufacturing Hub MAPP (Manufacture using Advanced Powder Processes). The objectives at the end of the project will be to transfer the knowledge to the High Value Catapult Centres for large scale exploitation into industry.

Through the EngD you will be gain valuable and career defining experience in titanium and/or nickel superalloy metallurgy, process modelling, FAST, thermomechanical processing, mechanical testing, a range of characterisation techniques (electron microscopy, XRD), finite element modelling (DEFORM), physics-based modelling (COMSOL) and thermodynamic modelling (ThermoCalc). You will be expected to present results to Rolls-Royce on a weekly basis and engage with their materials and process modelling teams

The EPSRC Centre for Doctoral Training in Advanced Metallic Systems was established to address the metallurgical skills
gap, highlighted in several reports [1-3] as a threat to the competitiveness of UK industry, by training non-materials
graduates from chemistry, physics and engineering in a multidisciplinary environment. Although we will have supplied ~140
highly capable metallurgical scientists and engineers into industry and academia by the end of our existing programme,
there remains a demonstrable need for doctoral-level training to continue and evolve to meet future industry needs. We
therefore propose to train a further 14 UK based PhD and EngD students per cohort as well as 5 Irish students per
cohort through I-Form.

Manufacturing contributes over 10% of UK GVA with the metals sector contributing 12% of this (£10.7BN [4,5]) and
employing ~230,000 people directly and 750,000 indirectly. It is estimated that ~2300 graduates are required annually to
meet present and future growth [5]. A sizeable portion of these graduates will require metallurgical expertise and current
numbers fall far short. From UK-wide HESA data, we estimate there are ~330 home UG/PGT qualifiers in materials and
~35 home doctoral graduates in metallurgy annually, including existing AMSCDT graduates, so it is unsurprising that
industry continues to report difficulties in recruiting staff with the required specialist metallurgical knowledge and
professional competencies.

As well as addressing this shortfall, the CDT will also impact directly on the companies with which it collaborates, on the
wider high value manufacturing sector and on the UK economy as a whole, as follows:

1. Collaborating companies, across a wide range of businesses in the supply chain including SMEs and research
organisations will benefit directly from the CDT through:

- Targeted projects in direct support of their business and its future development and competitiveness.
- Access to the expertise and facilities of the host institutions.
- Involvement in the training of the next generation of potential employees with advanced technical and leadership skills
who can add value to their organisations.

2. The UK High-Value Manufacturing Community will benefit as the CDT will:

- Develop the underpinning science and advanced-level knowledge base required by future high technology areas, where
there is high expectation of gross added value.
- Provide an enhanced route to exploitation, by covering the full spectrum of technology readiness levels.
- Ensure dissemination of knowledge to the sector, through student-led SME consultancy projects, the National Student
Conference in Metallic Materials and industry events.

3. The wider UK economy will benefit as the CDT will:

- Promote materials science and engineering and encourage future generations to enter the field, through outreach
activities developed by the students that will increase public awareness of the discipline and its contribution to modern
life, and highlight its importance to future innovation and technologies.
- Develop and exploit new technologies and products which will help to maintain a competitive UK advanced
manufacturing sector, ensure an internationally competitive and balanced UK economy for future generations and
contribute to technical challenges in key societal issues such as energy and sustainability.

References:
1. Materials UK Structural Materials Report 2009
2. EPSRC Materials International Review 2008
3. EPSRC Materially Better Call 2013
4. The state of engineering, Engineering UK 2017
5. Vision 2030: The UK Metals Industry's New Strategic Approach, Metals Forum