Special Issue "Advances in Structural Metallic Systems for Gas Turbines"

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: closed (31 December 2019).

Special Issue Editor

Dr. Mark T. Whittaker
E-Mail Website
Guest Editor
Institute of Structural Materials, Bay Campus, College of Engineering, Swansea University. SA1 8EN, Swansea, UK
Interests: thermo-mechanical fatigue, creep, fatigue lifing, titanium alloys, nickel-based superalloys
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Special Issue Information

Dear Colleagues,

The EPSRC Rolls-Royce Strategic Partnership for Structural Metallic Systems for Advanced Gas Turbine Applications was initiated in 2009 with sponsorship secured to provide a ten-year research and training programme underwritten by a memorandum of understanding between Rolls-Royce and EPSRC. This partnership is unique across the United Kingdom in the sense that it combines industry-led research at the postdoctoral level with a parallel scheme of postgraduate research training. Research themes are defined through collaboration between leading UK materials academics and industrial colleagues based within Rolls-Royce and its key supply chain companies. The research conducted under the strategic partnership provides an exemplar of academic–industrial knowledge transfer.

As the strategic partnership enters its tenth and final year, this Special Issue of Materials showcases some of the research performed in recent years. To act as a focal point for dissemination within the scheme, a conference is held regularly with one of the three core members of the partnership, Birmingham, Cambridge and Swansea universities, acting as host. “Satellite” universities including Imperial, Manchester, Cranfield, and Sheffield also provide welcome support to the industrially focussed research. The papers presented here are a reflection of the research presented at the fifth conference in the series, held at the Vale of Glamorgan hotel and organised by Swansea University. The conference deliberately encourages student presentations, with both EngD and PhD students presenting their work in either oral sessions structured around the technical work packages of the strategic partnership, or through extensive poster sessions. In many cases, the conference also provides a useful stepping stone to students looking to present their work to open audiences on the international stage. The contributions in this Issue provide a range of papers from industry, where future engineering and materials requirements are examined, and all three core universities.

As part of the EPSRC-RR Strategic Partnership, I encourage you to contribute papers to this Special Issue of Materials, focussed around the fifth conference in the series related to the partnership, to be held at the Vale of Glamorgan hotel, May 13–15th 2019. Previous collections of papers have proven to be very well received, and we hope for a strong collection of papers here.

Submissions are limited to members of the EPSRC-Rolls Royce Strategic Partnership in Structural Materials.

Dr. Mark T. Whittaker
Guest Editor

Manuscript Submission Information

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Keywords

  • EPSRC-RR Strategic partnership
  • Nickel
  • Titanium
  • Fatigue

Published Papers (5 papers)

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Research

Open AccessArticle
The Effect of Processing Variables on Powder Interlayer Bonding in Nickel-Based Superalloys
Materials 2020, 13(3), 601; https://doi.org/10.3390/ma13030601 - 29 Jan 2020
Abstract
Powder Interlayer Bonding (PIB) has been considered as a lower-energy joining technology for nickel-based superalloys compared to conventional methods; such as friction welding. Typically; nickel-based superalloys exhibit high energy requirements for joining due to their high operating temperatures. However; PIB utilizes a localized [...] Read more.
Powder Interlayer Bonding (PIB) has been considered as a lower-energy joining technology for nickel-based superalloys compared to conventional methods; such as friction welding. Typically; nickel-based superalloys exhibit high energy requirements for joining due to their high operating temperatures. However; PIB utilizes a localized temperature gradient created by an induction current; reducing the energy requirements for the process. PIB is a solid-state joining method that compresses and heats a powder interlayer between two faying surfaces to produce one joined workpiece. It has been successfully used to bond titanium alloys; and the objectives of this work were to explore its application as a joining method for nickel-based superalloys. Initial results showed that joining nickel-based superalloys via PIB is possible; and bondlines with very little porosity were observed. Further analysis showed that these bonded areas had lower porosity than the base material; suggesting PIB could be a successful joining method for difficult-to-join nickel-based superalloys. Full article
(This article belongs to the Special Issue Advances in Structural Metallic Systems for Gas Turbines)
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Open AccessArticle
Phase Equilibria in the Nb-Rich Region of Al-Nb-Sn at 900 and 1200 °C
Materials 2019, 12(17), 2759; https://doi.org/10.3390/ma12172759 - 28 Aug 2019
Cited by 2
Abstract
The Al-Nb-Sn phase diagram was studied experimentally in the Nb-rich region to provide important phase equilibria information for alloy design of Nb-silicide based materials for aero engine applications. Three alloys were produced: Nb-17Al-17Sn, Nb-33Al-13Sn and Nb-16Al-20Sn (at.%). As-cast and heat-treated alloys (900 and [...] Read more.
The Al-Nb-Sn phase diagram was studied experimentally in the Nb-rich region to provide important phase equilibria information for alloy design of Nb-silicide based materials for aero engine applications. Three alloys were produced: Nb-17Al-17Sn, Nb-33Al-13Sn and Nb-16Al-20Sn (at.%). As-cast and heat-treated alloys (900 and 1200 °C) were analysed using XRD (X-ray diffraction) and SEM/EDS (scanning electron microscopy/ electron dispersive x-ray spectroscopy). Tin showed a high solubility in Nb2Al, reaching up to 21 at.% in the Sn-rich areas, substituting for Al atoms. Tin and Al also substituted for each other in the A15 phases (Nb3Al and Nb3Sn). Tin showed limited solubility in NbAl3, not exceeding 3.6 at.% as it substituted Al atoms. The solubility of Al in NbSn2 varied from 4.8 to 6.8 at.%. A ternary phase, Nb5Sn2Al with the tI32 W5Si3 crystal structure, was found to be stable. This phase was observed in the 900 °C heat-treated samples, but not in the 1200 °C heated samples. Full article
(This article belongs to the Special Issue Advances in Structural Metallic Systems for Gas Turbines)
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Open AccessArticle
The Influence of Process Parameters and Build Orientation on the Creep Behaviour of a Laser Powder Bed Fused Ni-based Superalloy for Aerospace Applications
Materials 2019, 12(9), 1390; https://doi.org/10.3390/ma12091390 - 29 Apr 2019
Cited by 1
Abstract
Additive Layer Manufacturing (ALM) is an innovative net shape manufacturing technology that offers the ability to produce highly intricate components not possible through traditional wrought and cast procedures. Consequently, the aerospace industry is becoming ever more attentive in exploiting such technology for the [...] Read more.
Additive Layer Manufacturing (ALM) is an innovative net shape manufacturing technology that offers the ability to produce highly intricate components not possible through traditional wrought and cast procedures. Consequently, the aerospace industry is becoming ever more attentive in exploiting such technology for the fabrication of nickel-based superalloys in an attempt to drive further advancements within the holistic gas turbine. Given this, the requirement for the mechanical characterisation of such material is rising in parallel, with limitations in the availability of material processed restricting conventional mechanical testing; particularly with the abundance of process parameters to evaluate. As such, the Small Punch Creep (SPC) test method has been deemed an effective tool to rank the elevated temperature performance of alloys processed through ALM, credited to the small volumes of material utilised in each test and the ability to sample material from discrete locations. In this research, the SPC test will be used to assess the influence of a number of key process variables on the mechanical performance of Laser Powder Bed Fused (LPBF) Ni-based superalloy CM247LC. This will also include an investigation into the influence of build orientation and post-build treatment on creep performance, whilst considering the structural integrity of the different experimental builds. Full article
(This article belongs to the Special Issue Advances in Structural Metallic Systems for Gas Turbines)
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Open AccessArticle
Lifing the Effects of Crystallographic Orientation on the Thermo-Mechanical Fatigue Behaviour of a Single-Crystal Superalloy
Materials 2019, 12(6), 998; https://doi.org/10.3390/ma12060998 - 26 Mar 2019
Abstract
Thermo-mechanical fatigue (TMF) is a complex damage mechanism that is considered to be one of the most dominant life limiting factors in hot-section components. Turbine blades and nozzle guide vanes are particularly susceptible to this form of material degradation, which result from the [...] Read more.
Thermo-mechanical fatigue (TMF) is a complex damage mechanism that is considered to be one of the most dominant life limiting factors in hot-section components. Turbine blades and nozzle guide vanes are particularly susceptible to this form of material degradation, which result from the simultaneous cycling of mechanical and thermal loads. The realisation of TMF conditions in a laboratory environment is a significant challenge for design engineers and materials scientists. Effort has been made to replicate the in-service environments of single crystal (SX) materials where a lifing methodology that encompasses all of the arduous conditions and interactions present through a typical TMF cycle has been proposed. Traditional procedures for the estimation of TMF life typically adopt empirical correlative approaches with isothermal low cycle fatigue data. However, these methods are largely restricted to polycrystalline alloys, and a more innovative approach is now required for single-crystal superalloys, to accommodate the alternative crystallographic orientations in which these alloys can be solidified. Full article
(This article belongs to the Special Issue Advances in Structural Metallic Systems for Gas Turbines)
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Open AccessArticle
The Effect of Phase Angle on the Thermo-Mechanical Fatigue Life of a Titanium Metal Matrix Composite
Materials 2019, 12(6), 953; https://doi.org/10.3390/ma12060953 - 22 Mar 2019
Abstract
The thermo-mechanical fatigue (TMF) behaviour of a Ti-6Al-4V matrix composite reinforced with SCS-6 silicon carbide fibres (140 μm longitudinal fibres, laid up hexagonally) has been investigated. In-phase and out-of-phase TMF cycles were utilized, cycling between 80–300 °C, with varying maximum stress. The microstructure [...] Read more.
The thermo-mechanical fatigue (TMF) behaviour of a Ti-6Al-4V matrix composite reinforced with SCS-6 silicon carbide fibres (140 μm longitudinal fibres, laid up hexagonally) has been investigated. In-phase and out-of-phase TMF cycles were utilized, cycling between 80–300 °C, with varying maximum stress. The microstructure and fracture surfaces were studied using electron backscatter diffraction (EBSD), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), profilometry, and optical microscopy. The results have shown the damaging effect of out-of-phase cycling with crack initiation occurring earlier than in in-phase tests and crack propagation rates being accelerated in out-of-phase cycles. Fatigue crack initiation has been shown to be sensitive to crystallographic texture in the cladding material and thermo-mechanical fatigue test results can be considered according to a previously proposed conceptual framework for the interpretation of metal matrix composite fatigue. Full article
(This article belongs to the Special Issue Advances in Structural Metallic Systems for Gas Turbines)
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