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Location/Division: Cambridge

PhD Studentship – Evaluating  Fundamentals of Environmentally-assisted Cracking of Additively Manufactured Materials

Institutions

TWI

National Structural Integrity Research Centre (NSIRC)

The Additive Manufacturing Innovation Centre (AMIC)

Lancaster University

PhD Supervisor

David Griffiths

Kasra Sotoudeh

Liang Xingzhong

Pedro Rivera-Diaz-Del-Castillo

Funding Availability: Funded PhD Project (Students Worldwide)

Background

Additive Manufacturing (AM) technologies are rapidly maturing and while basic properties such as strength and impact toughness are widely reported, the environmentally-assisted cracking (EAC) behaviour is largely unknown. EAC mechanisms like stress corrosion cracking and hydrogen embrittlement are insidious failure mechanisms which occur where a susceptible microstructure is combined with a corrosive/hydrogen charging environment and stress, potentially leading to catastrophic failure and loss of life. Research is urgently needed to establish if AM materials behave similarly to traditional materials in terms of EAC mechanism(s) and therefore identify if standard approaches to prevent these failures are appropriate for AM components.

Project

This project is a collaboration between TWI and Lancaster University, and will characterise the EAC behaviour of AM deposits produced by powder bed fusion processes and industry standard materials like 316L stainless steel and nickel Alloy 718. Manufacturing parameters and deposits will be selected to produce materials considered representative for the consumable and process.

The PhD student will have the opportunity to explore the relationships between microstructure and environmental crack susceptibility by carrying out a range of corrosion tests in environments, where these materials would typically be considered to be susceptible to EAC. Throughout the programme, environmental testing will be coupled with pre- and post-test advanced characterisation. A ‘safe operating envelope’ will be established for each material and compared to industry experience of wrought/cast equivalents.

Test coupons will be extracted from bulk components and witness specimens will be directly deposited using each AM process to evaluate if witness specimens (deposited next to a component) are representative of the cracking behaviour observed in actual AM parts. 

Intended project objectives include;

•Identify if EAC mechanisms observed are consistent with equivalent wrought/cast materials;

•Propose necessary adjustments to industry standards and standard test procedures necessary for AM materials/parts;

•Publish environmental testing data necessary to give industry confidence that current/new approaches are appropriate for AM material;

•Develop a mechanistic understanding of EAC in AM materials.

•Identify if witness specimens deposited next to AM components are representative of actual parts, in terms of EAC susceptibility. 

About University/Department

Lancaster University is one of the UK’s leading research-intensive Universities consistently ranking no.1 in the NW of England and recently 137 in the world. Lancaster was the last of seven new UK universities conceived in the 1950s with 2014 marking its 50thAnniversary. Its 12,000 students belong to one of nine colleges, which act as interdisciplinary communities, but are taught by four academic faculties: arts and social sciences; health and medicine; management; science and technology. Lancaster University has created and established a world-class multidisciplinary Engineering and Data Science Institute that aims to set the global standard for a truly interdisciplinary approach to contemporary data-driven research challenge. The DSI aims to act as a catalyst for the field of Data Science and to provide an end-to-end interdisciplinary research capability - from infrastructure and fundamentals through to globally relevant problem domains and the social, legal and ethical issues raised by the use of Data Science. Conducting research across the following three themes (1) Environment, resilience and sustainability, (2) Health and ageing, (3) Data and society.

Lancaster University Engineering Department (top 10 UK University) recently set up the Additive Manufacturing Innovation Centre (AMIC). AMIC is a strategic partnership between Lancaster University and TWI with the aim of developing a comprehensive research capability focused on combining additive manufacturing with artificial intelligence and machine learning, also looking into new material approaches and processing. It will also be developing initiatives to certify Additive Manufacturing for serial production underpinned with academic research excellence with an industrial context. AMIC brings together expertise from TWI and Lancaster University to develop the international research profile and reputation of both partners in relation to AM, including the complete value chain of design and build optimisation, prototyping, performance validation and product industrialisation. Lancaster University had a long string of successful projects funded by EPSRC, NERC, MoD, EC, industry, The Royal Society and others in these research areas and the need to bring together these research activities and, in turn, generate an environment for closer multidisciplinary collaboration, generation of new ideas, initiatives and better opportunities for the graduate students, researchers and academics led to the establishment of the Centre.

About NSIRC

NSIRC is a state-of-the-art postgraduate engineering facility established and managed by structural integrity specialist TWI, working closely with lead academic partner Brunel University, the universities of Cambridge, Manchester, Loughborough, Birmingham, Leicester, Lancaster and a number of leading industrial partners. NSIRC aims to deliver cutting edge research and highly qualified personnel to its key industrial partners. 

Candidate Requirements

Candidates should have a relevant degree at 2.1 minimum, or an equivalent overseas degree in materials science, physics or chemistry, preferably with a focus on metallurgy, corrosion or environmental testing. Overseas applicants should also submit IELTS results (minimum 6.5) if applicable.

Funding Notes

This project is funded by Lancaster University, Lloyds Register Foundation and TWI. The funding covers the cost of Home/EU tuition fees and a standard tax-free RCUK stipend for three years. Non-EU students are welcome to apply, but the funding will only cover the cost of overseas tuition fees and the applicant need to self-fund their living cost for three years.

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