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 KEYNOTE AND INVITED SPEAKERS |
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| Full name of the lecturer |
David V. Edmonds |
Company |
University of Leeds |
Department |
Institute for Materials Research |
| Summary speaker resume |
David Edmonds' career in Physical Metallurgy has spanned 44 years at the universities
of Birmingham, Cambridge, Oxford and Leeds, where he is currently Professor of Metallurgy
and Materials. He has worked primarily on electron microscope studies of microstructural
formation and structure/property relationships in steels, but also in aluminium,
titanium, zirconium, tungsten and uranium alloys, and published around 230 technical
papers. He has spent two periods as Head of the Department of Materials at Leeds,
where his teaching is mainly in the areas of ferrous and non-ferrous alloys, process
metallurgy, deformation and fracture, and phase transformations. |
Title of the lecture |
Graphitization as a Potential Route to Improved Machinability of Carbon Steels |
Summary of the spoken topic |
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Exchanging cementite for graphite in carbon steel could be an alternative route
to improved machinability, and also result in better cold workability, than the
customary practice of adding elements such as Pb, S, Te, Se and Bi, some of which
impair cold forgeability or make recycling more difficult. However, the annealing
times required for graphitization are generally too long for industrial processing
of high volume products. In the present work, the graphitization process has been
accelerated by alloying with Si and Al, and the microstructural evolution during
graphitization treatment at 680°C monitored by microanalytical transmission electron
microscopy (TEM). Electron energy loss spectroscopy (EELS) and energy filtered transmission
electron microscopy (EFTEM) have been used to reveal information on the development of graphite nodules and on the accompanying dissolution of the cementite phase.
The overall graphitization process in the experimental steel was virtually complete
within a time scale ~2-4 hours, indicating a promising acceleration of graphitization
kinetics. A circumstantial link between dissolution of cementite and nucleation
of graphite in the experimental steel was identified. Different graphitization kinetics,
and hence different graphite dispersions, has also been detected between different
starting microstructures, for example, between bainite and martensite, which it
is proposed, provides additional, indirect evidence for the importance of the dissolving
cementite phase in the transformation process. |
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