After 18 months of research into her PhD topic (‘Structural Integrity Assessment of Wire and Arc Additive Manufacturing’), Cui Er Seow submitted a paper to the American Society of Mechanical Engineers (ASME) Pressure Vessels and Piping (PVP) 2018 Conference. Her paper was shortlisted for the Rudy Scavuzzo Student Paper Symposium and 26th Annual PVPD Student Paper Competition.
At the conference, Cui presented her work to an international audience with a mix of industrial and academic attendees. Her presentation was judged against presentations from six other students from different universities across the world, following which she was awarded the best presenting author of the Honourable Mention (PhD) category.
In recent years, there has been a significant interest in Additive Manufacturing (AM) technology. With humble beginnings, as rapid prototyping technologies intended to create prototypes quickly and cheaply, the same techniques are now being adapted and developed into alternative processes to manufacture components directly from a 3-D design. AM is defined as the process of joining materials layer-by-layer to form a 3-D shape. The final shape is typically derived from a computer aided design (CAD) model.
One such AM technology is Wire and Arc Additive Manufacturing (WAAM). WAAM is an advanced manufacturing process which uses wire as a feedstock and an electric arc as a heat source to build up metallic parts in successive layers. It is a high deposition rate near net-shape process, which (i) enables large components to be built within relatively short lead time, and (ii) reduces machining operations and material wastage as compared to traditional manufacturing routes i.e. casting, forging and machining. One industrial challenge is that during WAAM the part undergoes complex thermal cycling which results in epitaxial crystallite growth, leading to anisotropy in the microstructure. However, the effect of anisotropy in microstructure on mechanical properties has not yet been thoroughly investigated. The aim of Cui’s project is to:
- 1. Determine the microstructure and mechanical properties of WAAM components and assessing the deviation from wrought material.
- 2. Understand the influence of microstructural anisotropy on the mechanical properties of WAAM materials.
- 3. Evaluate the applicability of existing structural integrity assessment methods on WAAM components and make suitable recommendations.
The existing structural integrity assessment methods are mainly used for assessing metallic components or welded joints fabricated using traditional methods. The application of the existing structural integrity assessment methods on additively manufactured (AM) metallic parts is unknown. Standards/codes are currently not available to guide users to perform the assessment of AM parts. This has led to the slow adoption of AM in safety-critical applications. The outcomes of this research will provide evidence for the differences between WAAM and wrought materials in terms of its microstructure and mechanical properties. Using this evidence, methods to account for these differences will be developed to allow the accurate prediction of a WAAM component’s structural integrity.
These methods will contribute to structural integrity assessment standards, such as the BS7910 and R6, thereby allowing the WAAM technique to be adopted in industry. The development of robust standards for additive manufacturing will allow the industry to unlock this technology and reap the benefits of the technique, which include, but are not limited to, (i) improved part geometry, (ii) feasible low volume production, (iii) shorter lead-time on manufacturing of new components, (iv) raw material savings and hence (v) reduced part cost. These methods may be extrapolated to components made with other additive manufacturing techniques, which have similar issues with microstructural anisotropy. This research promises to make a transformative contribution to metal AM technology.
For more information, or to speak to Cui’s about her research, please contact firstname.lastname@example.org.