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Process, microstructure and property relationships in dissimilar nickel base superalloy inertia friction welds

Daus, Friedrich Herbert (2010)
Ph.D. thesis, University of Birmingham.

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Abstract

The objective of this research was to study the difference in microstructure and high temperature fatigue behaviour between three RR1000 to IN718 inertia friction welds and to provide further understanding of the inertia friction welding process. Between the three welds no significant differences in the weld microstructures were found. Also high temperature fatigue crack growth tests within 0.3 mm of the weld interface, showed no difference in crack growth rate due to the three different sets of welding parameters. The cracks were found to propagate from RR1000 through the weld interface into IN718 passing a 10-30 mm wide zone, allowing higher crack growth rates. Fractographic studies have shown that these higher crack growth rates are caused by a higher tendency to intergranular cracking. In the present welds a semi-solid weld contact layer of 10 - 30 mm thickness developed, being an intermediate alloy of varying composition of the two base materials. In the surrounding material constitutional liquation of NbC particles in IN718 and of primary γ′ in RR1000 occurred. Similar welding process characteristics during the final second of the three welding cycles resulted in the observed similar weld microstructure and high temperature fatigue properties. It was further found that the local fatigue crack growth rate increase occurs in the weld contact layer.

Type of Work:Ph.D. thesis.
Supervisor(s):Bowen, Paul and Li, Hang Yue
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:School of Metallurgy and Materials
Keywords:Inertia Friction Welding Nickel Base Superalloy
Subjects:TJ Mechanical engineering and machinery
TN Mining engineering. Metallurgy
Institution:University of Birmingham
ID Code:1062
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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