The Effects of Local Texture and Microstructure on Deformation Mechanism in IN 713C Alloy

Lead Research Organisation: Swansea University
Department Name: School of Engineering

Abstract

The turbocharger is an essential part of a modern diesel engine. The turbine wheel is a key component in the turbocharger and it should be designed to sustain at high temperatures and high rotational speeds during the hostile operating conditions and strenuous duty cycles. Mainly the material used in the turbine wheel is Inconel 713C which is a precipitation hardenable, nickel- chromium base cast alloy. The turbocharger manufactures' requirements imposed on this cast alloy is high as it should includes high fatigue and creep resistance at high temperatures as well as resistance to corrosion in a media containing products of fuel combustion. However, the turbine wheel blades are thermally and mechanically loaded during the operation of the turbocharger that can lead to material failures. With the objective to design safe components and improve fuel consumption, it is necessary to understand the failure mechanisms of the employed materials under these complex loadings. Different failure modes reported in literature, but the two most prominent turbine wheel failure modes are Low Cycle Fatigue (LCF) and High Cycle Fatigue (HCF). In general, there is uncertainty in literature about the exact influence of individual microstructure parameters including porosity, inclusions, grain orientation and slip activity on fatigue life of IN 713C alloy. In a complex system such as cast IN 713C alloy, these parameters should be identified and quantified. This needs complete description of the microstructure and microtexture of the alloys prior and post mechanical testing using various microanalytical tools including HR-SEM, HR-EBSD, EDX, X-ray micro-tomography as it suggested in this proposed study.

Conventionally, the crack initiation and propagation during tension, creep and fatigue have always been correlated to some prominent microstructural features such as porosity, inclusions, voids, second phase particle, oxidation and surface conditions in most structure/property relationship studies. However, in a non-homogenous cast microstructure, the role of local zones/regions became very critical in materials performance and integrity. These local regions contain different grain/grain boundary distributions and local textures that create various microstructure/microtexture clusters that can promote/trigger crack initiation and provide fast crack propagation in some specific locations within the material. In this proposed study, along with defect distributions and surface condition of the alloy, other microstructure features including grain orientations, local/micro/macro/meso texture, strain distribution and grain boundary geometry/characteristics will be the focal points in understanding fracture mechanics, failure and deformation mechanisms. The aim of this study is to quantify and discriminate exact microstructural parameters that produced dissimilar crack characteristics in various zone/regions within a cast microstructure. Uniquely, here the parameters that caused crack formation at the surface will be quantified and compared with subsurface cracks and cracking in the bulk materials i.e., away from surface, edges and corners. Moreover, the crack formation in the absence of any microstructural defects will be characterised against the cracks formed in the vicinity of pores and inclusions. Identifying these microstructural parameters is fundamental in understanding the crack initiation and propagation correlation with microstructure and microtexture in cast alloys used at critical high temperature applications. Detailed investigation will be carried out in order to find exact interactions of the crack path, undulation and bifurcation with microtexture clusters that contain different strain/stress accumulations within the material. In this proposed study, in order to validate correlations between microstructure and crystallographic texture (local and global) with crack characteristic various micro-analytical tool will be employed.

Planned Impact

As stated in the Pathways to Impacts section, this proposed research study aligns very well with two of the current EPSRC themes and a recent EPSRC call. The main beneficiaries of the project include industrial partner Cummins Turbo technologies, Swansea University and the wider community as described in the Pathway to Impact section. Moreover, it has direct impacts on environment, society and knowledge as described here.

Cummins Turbo Technologies will benefit from the outcomes of this research study to improve the microstructure, processing, mechanical properties and temperature capability of the material used in turbocharger components. This study will provide a better understanding of the deformation mechanisms and structure/property relationship in IN713C alloy that can guide Cummins towards enhanced product properties. From this fundamental scientific investigation, Cummins will gain better understanding of the material integrity and performance used in turbocharger and the methodology of improving the properties for such an alloy. A specific impact activity will be undertaken by the project to ensure the knowledge is transferred and embedded to the engine industry. This project will also lead to effective engagement and collaboration between Swansea University and Cummins. Furthermore, based on the originality and novelty, this project will attract further collaborators in automotive, aerospace and nuclear industries, especially in the field of deformation mechanism for the new designed alloys. This project also raises the UK profile and facilitates generation of additional international research funding for UK academics as this project will leads to better scientific understandings of materials integrity of the commercial alloys. This project will also help the industrial partner Cummins to engage actively with the research activity in Swansea University.

Swansea University will benefit from this study, as it will provide an opportunity for employing a Post Doctoral Research Associate (PDRA) to be trained in a directly related industrial project. There will be also an opportunity to allocate MSc and final-year BEng/MEng students to work directly with PDRA/PI on this projects. This will help in training new engineers for the materials engineering fields in a growing energy sectors.

This project is generic in nature and applicable to the majority of alloys used in critical aerospace and nuclear applications. This study provides a new approach to examine the materials stability and durability. This can applied to the newly designed intermetallic compounds and superalloys that are carefully manufactured to be free from any type of defects and considered to have superior microstructure and mechanical properties. This project will advance UK based fundamental science in deformation and failure mechanism research areas. This project will also help our existing expertise and knowledge in our college at Swansea University as well as the community through public engagement and awareness about the major issues in materials failures that can cause catastrophic failures. The outcomes of this project will be published and presented in national and international meetings, which helps in disseminating the findings to wider scientific and industrial communities.

Finally, this proposed project is directly related to the challenges facing the engine industry that have been focused on meeting emissions regulations. Improving turbocharger efficiency can reduce emissions and increase power and economy fuel consumption. Optimising the material integrity and performance of the turbocharger components can contribute greatly in achieving best functionality of the turbocharger used in many critical applications. This important related material aspects are directly relate to the energy and wealth management as well as emission legislation as it contributes greatly in controlling and reducing fuel consumption.

Publications

10 25 50
 
Description The wheel mechanical property is the most important aspect during the manufacturing of a turbocharger, (which is used in many transport, energy, aerospace, automotive applications). However, there are many processing parameters should controlled carefully to produce a material for the wheel with a suitable microstructure. In this study which funded from this grant, it is concluded that there is a direct link between the processing parameters and microstructure and texture (crystallographic orientation of the grains within the materials). From this, exact structure- property relationship is established for IN713L nickel base superalloy which is used in the wheel production.
Exploitation Route The findings from this study reported to Cummins Turbo Technology (the industrial partner for this project). The Cummins sent their recommendations based on this project conclusions to the materials/parts suppliers in order to enhance the property of the alloy, considering the processing parameters they use.
Sectors Aerospace, Defence and Marine,Energy,Manufacturing, including Industrial Biotechology,Transport

 
Description The findings from this project resulted in: Re-considering the investment casting industrail parameters used by the suppliers for Cummins Turbo Technology (this project industrial partner). This included the temperature and cooling rate used during the casting. The recommendations throughout this project was reported from Swansea to Cummins, hence to the suppliers.
First Year Of Impact 2015
Sector Aerospace, Defence and Marine,Energy,Manufacturing, including Industrial Biotechology,Transport
Impact Types Economic

 
Description China Scholarship Council (CSC) for full cost of overseas tuition fees, research expenses and living expenses.
Amount £34,000 (GBP)
Organisation University of Leeds 
Department China Scholarship Council
Sector Academic/University
Country United Kingdom
Start 10/2015 
End 09/2018
 
Description DTA- Fully funded PhD scholarship
Amount £45,000 (GBP)
Organisation Dental Technologists Association 
Sector Charity/Non Profit
Country United Kingdom
Start 10/2014 
End 09/2017
 
Title GND Measurement 
Description Measuring dislocation density in FCC metals by means of electron backscatter diffraction techniques. 
Type Of Material Improvements to research infrastructure 
Year Produced 2014 
Provided To Others? Yes  
Impact Can be used to measure dislocation density (line defects) in any FCC materials. 
 
Title Transmission EBSD 
Description Using transmission Electron Backscatter Diffraction (TKD) tools in order to identities very small particle with nickel based superalloy microstructure. Also to perform orientation mapping at nano-scale. The techniques was achieved the required analysis. 
Type Of Material Technology assay or reagent 
Year Produced 2014 
Provided To Others? Yes  
Impact TKD, used in this study was a starting points fro other research coup in college of engineering - Swansea University to develop this techniques and apply it in a wider research field. 
 
Description Agreement between collaborating partner to recruit a PhD student to assist in this EPSRC funded project 
Organisation Cummins
Country United States 
Sector Private 
PI Contribution Following the appointment of a research associate to work on this EPSRC funded project, an agreement has been made between myself (PI) and Cummins Turbo technology (Industrial collaborator of this project) to recruit a PhD student to help the existing team. The PhD was funded by EPSRC DTA - Swansea univerity grant for 3 years. All the mechanical testing, microstructure characterisation and experiments will be carried out in Swansea University. It is also our responsibility to support and fund the student for 3 years and provide technical and scientific expertise throughout this project.
Collaborator Contribution Cummins supplying all the materials required for this project.
Impact N/A
Start Year 2014
 
Description Attending and presenting a talk in 144th TMS 2015 Conference, Orlando, USA. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact Attending and presenting a talk in 144th TMS 2015 Conference, Orlando, USA. This is one of the best international conferences in Materials Engineering field. Presenting our research results in this conference it will enhance our expertise and reputation in this field.

Further discussion on this critical field in physical and mechanical metallurgy within the wider material community internationally.
Year(s) Of Engagement Activity 2014
 
Description Presenting the results from this project in ICOTOM conference in Dresden/Germany. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact Attending and presenting a talk about our research finding and activities in 17th International Conference on Texture of Materials
Dresden, Germany (ICOTOM 17). This is one of the best international conferences in Materials Engineering field.

Following my talk there was an informal discussion about our finding and experimental methodology presented in the talk. This contributed greatly in sharing information and planing for next reach activities with Ghent and Delft Universities.
Year(s) Of Engagement Activity 2014
 
Description Progress Meeting with industrial partner Cummins Turbo technologies 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact So far, we had two major group meeting with the industrial partner Cummins Turbo Technologies team in Huddersfield/UK (i.e., managers, researchers and technical directors and students). Our team in Swansea university included myself (PI), the research assocaite who appointed on this grant, and the PhD student. We presented a talk to cover out findings to be open for discussion with the industrial partner.

Following our discussion with technical directors, managers and researchers in Cummins, a suitable plan for future work have arranged, more materials were supplied, an agreement on the next experimental details and procedure was reached. In addition, decisions were make on the pretend results and previous experiment to be continued or terminated during the project time. further work packages were agreed whiten the same budget.
Year(s) Of Engagement Activity 2014