Oral Presentations

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Miles Cooke - Session 6 (Wed 11.15-12.55)

University of Manchester

Examining the Combined Effect of Irradiation and Microsegregation on the Microstructure and Mechanical Properties of Low Alloy Steel Welds

When exposed to nuclear radiation, reactor pressure vessel (RPV) steel experiences a change in microstructure, such as solute clustering, grain boundary segregation, and precipitate formation. Features such as these contribute to the hardening and embrittlement of the steel, weakening RPV integrity.

Electron beam welding (EBW) of SA508 grade 4N steel has produced autogenous welds, which exhibit microsegregation, of nickel for example. It is hypothesised that solute enriched regions of the weld may experience more severe irradiation induced microstructural changes than solute depleted regions. The presence of EBW microsegregation during irradiation is under investigation, to determine if a deleterious synergy exists.

Pat Curran - Session 3 (Tue 14.00-15.40)

University of Manchester

An investigation into the effect of strain localisation on forged β-annealed Ti-6Al-4V

Co-authors: Pratheek Shanthraj, Philip Prangnell, Nicholas Byres, Benjamin Dod, Michael Atkinson, Adam Plowman, Dongchen Hu, João Quinta da Fonseca

Fatigue crack initiation predictions using crystal plasticity (CP) is difficult as they need properly validated input parameters, such as critically resolved shear stress. In this work, high resolution digital image correlation (HRDIC) is used to validate CP predictions of slip activation and strain localisation in Ti-6Al-4V. Slip activation and intensity of strain localisation were compared experimentally to computationally on a grain-by-grain basis. The experiments showed that pyramidal<a> type slip was the first to be activated. On average the CP model did predict the correct level of strain localisation.

Samuel Eka - Session 2 (Tue 11.15-12.55)

University of Manchester

Data Management of Through-life Nuclear Welds for Structural Integrity Assessment

The need to demonstrate through-life safety and longevity of operational assets has led to the drive towards datacentric engineering approaches, as an addition to the established methods for structural integrity assessments, such as experimental and computational methods.

Building on previous work demonstrating the use of data for datacentric evaluation of asset performance, this phase of research focuses on the design of data models based on concepts adopted from the Functional Genomics Experimental Model (FuGE).

Data models are designed using Unified Modelling Language (UML) class diagrams for aspects of welding component Lifecyle (manufacture, material characterisation and measurements). The practicality of the class diagrams is verified using UML Object diagrams.

Aiden Ha - Session 1 (Tue 09.00-10.55)

University of Manchester

Modelling texture driven abnormal grain growth during beta annealing of an alpha-beta Ti alloy

Co-authors: Adam Plowman (UKAEA,University of Manchester), Pratheek Shanthraj (UKAEA,University of Manchester), Philip Prangnell (University of Manchester), João Quinta da Fonseca (University of Manchester)

We use a phase-field approach developed by Plowman to investigate texture reversion in γ-fibre grains during β annealing of hot rolled Ti-6V-4Al. Initially, large misoriented grains grow before being absorbed by the subgrain matrix. This is modelled as a rogue γ-fibre nucleus in a rotated cube sub grain matrix where varying grain boundary (GB) energy and mobility values in the nucleus-subgrain and subgrain-subgrain interfaces can mimic texture effects. Here, adjusting mobility ratios can significantly affect γ-fibre lifespan, though microstructural realisations with the same parameters show a range of grain lifetimes. Interestingly, weakening the subgrain matrix texture increases the nucleus lifetime.

Saeid Heidarinassab - Session 5 (Wed 09.00-10.55)

Dublin City University

Investigation of ablation efficiency and silicon carbide nanoparticle properties obtained using pulsed laser ablation in liquid

Co-authors: Inam Ul Ahad, Dermot Brabazon

This study focuses on the synthesis and ablation efficiency optimisation of silicon carbide (SiC) NPs through the implementation of nanosecond pulsed laser ablation in liquid. Systematic variations in process parameters, laser fluence, scanning speed, and ablation time were conducted to investigate their influence on ablation efficiency and the resulting NPs properties. Statistical analysis was employed to optimise ablation efficiency, revealing that the most effective conditions for generating concentrated SiC NPs were a 15-minute ablation time, a scanning speed of 0.5 m/s, and a laser fluence of 7.5 J/cm2. Colloids were characterised using UV-Vis, Dynamic Light Scattering (DLS), Field Emission Scanning Electron Microscopy (FESEM) equipped with energy dispersive X-ray (EDX), Field Transmission Scanning Electron Microscopy (FTSEM), and XRD were used to determine the elemental composition and phase composition of the produced NPs. The results indicated that an increase in laser fluence, scanning speed, and ablation time led to higher colloid concentrations. Notably, the shape and size of the nanoparticles remained relatively constant despite variations in the laser processing parameters. XRD patterns suggested that the resulting NPs has the same phase composition as the target material which was found to be 3C SiC. The measurements obtained through image analysis yielded NPs sizes smaller than those determined through DLS. Furthermore, a direct correlation was observed between the ablated mass and colloid concentration, where increasing the ablated mass resulted in a corresponding increase in colloid concentration.

Philomenah Holladay - Session 5 (Wed 09.00-10.55)

University of Sheffield

Accelerated modelling of ratchetting and shear strain accumulation in rail steels using GPU based parallel computing

Co-authors: David Fletcher (University of Sheffield), Francis Franklin (University of Newcastle)

The dynamic ratchetting (Dynarat) model, developed in 2001, discretises a section of rail into a grid of elements called ‘bricks’, each of which are characterised by material properties such as shear yield and critical shear strain. Originally used to model wear and microcrack behaviour in rail steels, lack of strain continuity between bricks and limited scale were deficiencies of that could not be addressed previously. However, the FLAME GPU framework, Flexible Large-scale Agent Modelling Environment for Graphics Processing Units, has allowed for the model to be expanded dimensionally, and for the addition of bonds between bricks to address continuity issues.

Joe Hopkinson - Session 6 (Wed 11.15-12.55)

University of Sheffield

Producing Multi-Alloy and Functionally Graded Titanium Billets using Field-Assisted Sintering Technology (FAST)

Titanium aerospace components are typically composed of a single alloy throughout their structure, which can result in components being over-engineered in certain regions. This is due to components being designed to withstand the most extreme conditions any sub-component region experiences. This could be temperature, stress, creep, foreign object damage FOD or low/ high cycle fatigue (LCF/HCF). Multi-alloy and functionally graded components have the potential to eliminate the need to over-engineer in this way. They would allow for the microstructure to be tailored for the specific properties required in each sub-component region. This project demonstrates the feasibility of producing multi-alloy titanium billets by combining Aerosint’s selective powder deposition (SPD) process with Field-Assisted Sintering Technology (FAST) in addition to laying powders using dividers. SPD can precisely fill a graphite mould by printing single powder layers composed of up to three materials, to a quoted resolution of 300 μm. FAST then consolidates the powder and facilitates diffusion bonding between the dissimilar alloys. FAST works by simultaneously applying a pulsed DC current and a uniaxial pressure to the sample. Ti-6Al-2Sn-4Zr-2Mo (Ti-6242), Ti-6Al-4V (Ti-64) & Ti-5Al-5Mo-5V-3Cr (Ti-5553) powders were printed in a triple helix design through SPD and fully consolidated using FAST. The microstructural evolution of the three alloys and the bonds between them were analysed through optical and scanning electron microscopy to evaluate the effectiveness of the novel combined process.

Ciaran Miles - Session 2 (Tue 11.15-12.55)

University of Sheffield

The Evaluation of AlSi-Based Coatings on Automotive Steel and Their Potential HEA Replacements

Co-authors: Katerina Christofidou (University of Sheffield), Russell Goodall (University of Sheffield), Adrian Leyland (University of Sheffield) & Ralf Rablbauer (Volkswagen Group Innovation)

Al-Si is the current standard of multiple manufacturers when it comes to the protection of automotive steel throughout a car’s service life. Although renowned for its ability to protect the steel through the press-hardening process, molten aluminium attack on the rollers as well as other reasons has led to the question of a viable replacement. HEAs offer a potential alternative with a near-unlimited scope. So far both hot-dipping and physical vapour deposition have been trialled to apply both Al-Si and future HEA trial coatings. Successful coatings will then be used to determine the standards of protection on which a replacement must strive to beat.

Sampreet Rangaswamy - Session 5 (Wed 09.00-10.55)

Dublin City University

Development of Predictive Model for Single Track Laser Powder Bed Fusion of Nitinol

Co-authors: Declan Bourke, Inam Ul Ahad, Dermot Brabazon Dublin City University

Due to its distinctive properties such as shape memory and super-elasticity, Nitinol (NiTi) finds applications in diverse fields, notably in aerospace and biomedical industries. Additive manufacturing, a process involving the layer-by-layer construction of components, enables the production of intricately shaped parts with precise dimensions. In this study, powder bed fusion using laser beam (PBF-LB) technology was employed to fabricate single-line tracks of NiTi. The impact of scanning parameters, specifically laser power and scanning speed, on melt pool dimensions was thoroughly examined. To predict melt pool widths and depths, a numerical model was formulated using Ansys Additive Suite software. Experimental methodologies, including laser flash analysis (LFA), differential scanning calorimetry (DSC), and dilatometry (DIL), were employed to acquire temperature-dependent thermophysical properties of NiTi necessary for the Ansys simulations. Subsequently, these obtained data were verified against results obtained through the CALPHAD method using Thermo-Calc software.

Shahrzad Sajjadivand - Session 3 (Tue 14.00-15.40)

University College Dublin

Understanding the Differences in Microstructural Evolution between Additively Manufactured and Conventional 18Ni(300) Maraging Steel upon Post-Processing Heat Treatment

Co-authors: Mert Celikin: University College Dublin, Mark Hartnett: Irish Manufacturing Research (IMR), and Denis Dowling: UCD

This study aims to optimise post-processing heat treatment methodology of 18Ni(300) Maraging steel manufactured via Laser Powder Bed Fusion (L-PBF). This is achieved by understanding the effect of post-processing heat treatment on the microstructural evolution and mechanical behaviour of L-PBF 18Ni(300) Maraging steel in comparison to conventionally manufactured 18Ni(300) Maraging steel. In-depth materials characterisation was carried out using X-ray diffraction (XRD), optical and scanning electron microscopy (OM/ SEM), and transmission electron microscopy (TEM). Resultant changes in mechanical properties determined via hardness testing were linked with precipitation kinetics. Based on conventionally produced 18Ni(300) steel as a control and baseline, a novel heat treatment methodology has been developed for AM maraging steels.

Niels Schreiner - Session 6 (Wed 11.15-12.55)

University of Sheffield

Short range order analysis of Ni4Mo through total scattering

Co-authors: Lewis R. Owen (Sheffield University), Philip Chater (Diamond Light Source)

Molybdenum is an important solid solution strengthening element for the gamma phase in Nickel Based Superalloys (NBS). Dislocation pile-up identified in TEM studies of NBSs have suggested local ordering within this gamma phase. Consequently, understanding the local ordering behavior of the Ni-Mo system would elucidate the strengthening mechanism that Mo provides. Despite an abundance of literature on the subject, the local ordering of Ni4Mo remains highly debated. This presentation will focus on the work done towards the elucidation both the ordering pathway and presence of short-range order within Ni4Mo through application of total scattering analysis and large box modelling.

Durga Tilak - Session 2 (Tue 11.15-12.55)

University of Sheffield

Eddy Current Generation in Magnets: An Analytical and Finite Element Approach

Co-Authors: Dr Julian Dean (The University of Sheffield), Prof Thomas J Hayward (The University of Sheffield), Dr Zdeno Neuschl (Volkswagen Group)

With advancements in electric vehicular technology, the performance of each component in its power train has become the subject of detailed analysis. Research on the architecture and efficiency of motors has produced novel motor structures that improve torque and power ratings, but a significant portion of the motor power can be lost through the generation of undesired eddy currents within magnets located in the motor core. This presentation investigates the generation of eddy currents in magnets by using an analytical and finite element approach. It explores how the magnetic material properties are important in loss and shows possible power loss–mitigating solutions by modifying the shape of the magnet.

Martin Tse - Session 1 (Tue 09.00-10.55)

University of Sheffield

Samuel Yeates - Session 1 (Tue 09.00-10.55)

University of Sheffield

Impact of temperature and irradiation on the formation and stability of TiCON precipitates in V-4Cr-4Ti and Vanadium-containing Compositionally Complex Alloys

Co-authors: Prof. Russell Goodall - (The University of Sheffield), Dr. Christina Hofer - (The University of Oxford), Dr. David Bowden - (UKAEA), Prof. Amy Gandy - (UKAEA)

Components in commercial nuclear fusion devices will face some of the most extreme operating conditions on the planet including elevated temperatures and high-flux fast neutron irradiation. Vanadium alloys offer many beneficial properties in these environments, however unless material purity is very carefully controlled, undesired TiCON precipitates form. 
This work aims to explore the irradiation and temperature stability of the TiCON precipitates on a multi-length scale along with their behaviour in the reference composition V-4Cr-4Ti and two reduced-activation compositionally-complex alloys 30Ta-30V-30Ti-5W-(5Fe,5Cr).

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