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Details of Grant 

EPSRC Reference: EP/L014572/1
Title: The Effects of Local Texture and Microstructure on Deformation Mechanism in IN 713C Alloy
Principal Investigator: Birosca, Professor S
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Department: College of Engineering
Organisation: Swansea University
Scheme: First Grant - Revised 2009
Starts: 24 March 2014 Ends: 23 September 2015 Value (£): 98,477
EPSRC Research Topic Classifications:
Eng. Dynamics & Tribology
EPSRC Industrial Sector Classifications:
Aerospace, Defence and Marine Manufacturing
Related Grants:
Panel History:
Panel DatePanel NameOutcome
01 Oct 2013 Engineering Prioritisation Meeting 1 October 2013 Announced
Summary on Grant Application Form
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.
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Organisation Website: http://www.swan.ac.uk