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Machining of nickel based superalloys using coated PCBN tooling

Khan, Sarmad Ali (2014)
Ph.D. thesis, University of Birmingham.

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Following a comprehensive literature review on the machinability of nickel based superalloys using conventional carbide, coated carbide and ceramics including uncoated/coated PCBN, the research details statistically designed experimental work to assess the tool life/wear performance and workpiece surface integrity of a range of uncoated and coated PCBN tools, when turning solution treated and aged Inconel 718. Typically, the use of carbide tooling is limited to < 60 m/min cutting speed, even with the use of high pressure cutting fluids (JetStream systems). Hardmetal coatings provide some productivity improvements although cutting speed restrictions still operate. Details of PCBN use at up to 600 m/min have been published but at the expense of tool life. Experimental testing of a number of uncoated PCBN grades involving both high and low CBN concentrations, indicated a preferred operating window of ~ 300 – 400 m/min. Advanced ceramic coatings provided no significant benefits. Primary tool wear mechanisms related to abrasion, workpiece adhesion/diffusion and fracture depending on the specific operating parameters employed. In depth workpiece integrity evaluation involving surface roughness, microstructure, microhardness and residual stress measurement suggested only limited damage when operating with PCBN tooling at preferred/optimised conditions.

Type of Work:Ph.D. thesis.
Supervisor(s):Soo, Sein Leung and Aspinwall, David K.
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:School of Mechanical Engineering
Additional Information:

Embargo expiry date: 31/07/2018

Subjects:TJ Mechanical engineering and machinery
Institution:University of Birmingham
ID Code:5111
This unpublished thesis/dissertation is copyright of the author and/or third parties.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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