Development of Advanced High Modulus Steels for Automotive Applications

Although there has been much activity in the automotive sector in the area of advanced high strength steels (AHSS), with the objective of achieving high strength while exhibiting high stretch formability, there is a new generation of steels under consideration for automotive applications (Fig. 1). These steels are predicated on achieving weight reduction while exhibiting a high modulus of elasticity as part of the design criteria, and such steels are referred to as high modulus steels (HMS). This project aims to develop high modulus, high ductility steels with reduced density that can be produced at an industrial scale. This is with the ultimate aim of opening up the lightweight design window to increase performance and efficiency of transport systems. One potential route to achieving this combination of properties is to create a composite microstructure by combining light and stiff particles with a strong a ductile metallic matrix. This research programme will examine potential in-situ composite systems based on TiB2, NbB2 and/or VB2 particles utilising conventional liquid casting methods in addition to powder production/consolidation methods.
A clear objective of the research is to establish the feasibility for the use of HMS in automotive components. This will be achieved by adopting a parallel processing approach 1. Produced using vacuum induction melting followed by thermomechanical processing (TMP), and 2. Produced using field assisted sintering technology (FAST) coupled with single stage TMP. All facilities for this testing will be performed in Sheffield as part of the Henry Royce Institute (HRI). Quantitative characterisation of the microstructures as a function of the various processing stages will be conducted for the HMS produced by both processing routes, in addition to full mechanical testing (tensile, impact) of the HMS as compared with the monolithic base steel composition properties.
Field Assisted Sintering, FAST (sometimes known as Spark Plasma Sintering) is a novel manufacturing technique used to rapidly consolidate powders 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. This process enables the formation of in-situ composites at a much smaller length scales than conventional processing, offering the opportunity to develop components with the desired combination of stiffness and ductility.

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