It has previously been highlighted (see The FESI Bulletin, Autumn/Winter 2019) that various key ‘themes’ have been identified as part of a more structured approach going forward on the way we go about organising FESI-related events for the increased benefit of our members and for the structural integrity community in general.
During a FESI Council meeting held on February 27, 2020 at the University of Leicester, the ‘champions’ of four of the themes presented initial information they had each compiled on providing an introduction of their theme and potential planned events to be held over the next year or so aimed at progressing the theme. We will publish their conclusions as each theme progresses over the coming months.
Below, Professor Bo Chen outlines the FESI Theme of New Manufacturing and Joining Techniques
Background
The rapid solidification during additive manufacturing (AM) process can lead to much refined but non-equilibrium microstructures, inhomogeneous element segregation, non-conventional phase transformation, and heterogenous structures. In the past decade, AM is a fast-growing field and has already demonstrated its cost-competitive capability for fabricating some aerospace components/parts. For example, several aerospace companies have already used electron beam melting to fabricate TiAl-alloy low-pressure turbine blades. This can be also evidenced by the number of publications on titanium alloys and nickel-base superalloys. The FESI is aimed to extend the expertise developed for the aerospace industry towards a wider range of industrial sectors through different channels. To this end, a 5-year plan has been agreed to define the theme of ‘New Manufacturing and Joining Techniques’ particularly in relation to safety-critical engineering parts/components.
The objectives of this FESI theme are to: (i) understand the technical aspects and developments achieved in AM; (ii) identify the structural integrity aspects and challenges associated with the AM and other new manufacturing and joining technologies (e.g. high energy beam welding processes, advanced brazing and soldering); (iii) aid the facilitation of addressing the challenges. Note: this FESI theme is not limited exclusively to AM techniques. This is because we believe that any new manufacturing techniques share the same barrier before entering the safety-critical industries, namely, demonstrating their engineering structural integrity—fatigue, creep and corrosion to name a few. The safety-critical industries are those for which the consequence of their high-integrity component failure would be very severe: pressure vessels and piping, pipelines, cranes, bridges etc.
Take nuclear industry as an example. Nuclear power plant components have specialised requirements for performance, durability and longevity. Even seemingly simple components such as plumbing, fittings, valve housings, brackets and vessels must survive aggressive environments with radiation exposure, high temperatures, and high pressures for 60 years or more. Unfortunately, our current understanding about fracture and cracking behaviour of AM metals in relation to their unique microstructural features is limited. Consequently, further understanding of material performance is needed before AM can be employed to fabricate the load-bearing structures for safety-critical industries. Without listing an endless series of engineering challenges, we’d rather invite you to join this conversation by sharing your specific examples of components for which any new manufacturing and joining techniques would either be cost-effective or offer improved properties, but currently being held back due to structural integrity concerns.
Seminar workshops
(1) Run a workshop with the aim to form an AM roadmap for UK’s nuclear industry (2020 Q4 or 2021 Q1).
- To identify a couple of nuclear power components/parts for which AM can play a vital role
- To develop nuclear component AM standards and process/parts qualification
- To develop a cost model to explain the economic advantage of AM against other conventional means
- Conventional GEN III and III+, Advanced GEN IV and UK’s AMRs, Nuclear Fusion
(2) Organise a session in the next FESI–ESIA conference around this topic area (2021 Q2).
(3) A cross-theme workshop with Dr Hadley and Dr Wu (TWI) with the aim to encourage a two-way communication between people who work on AM materials and those work on structural integrity code and standard developments (2021 Q4).
Bo Chen
Professor of Engineering Materials,
University of Leicester