Year

2018

Degree Name

Doctor of Philosophy

Department

School of Mechanical, Materials, Mechatronic and Biomedical Engineering

Abstract

Significant efforts have been made in recent years to improve the ductility of ultra-fine grained/nanograined (UFG/NG) materials while preserving their high strength. Fabricating materials with gradient structures has been regarded as an effective approach to improving both ductility and strength. The sizes of the gradient material samples fabricated by the existing methods are limited. To date, a large-scale industrial application has not been reported due to a lack of reliable technologies capable of producing such materials at large volumes.

In this thesis, a process using the Accumulative Skin-Pass Rolling (ASPR) technique was developed to fabricate the large-volume metallic strips with gradient structure. The mechanical properties and microstructure in the ASPR processed aluminium (AA6061) and copper were systematically investigated. The effects of three ASPR process, namely, the friction at the roll/sample interface, roll speed ratio and thickness reduction par pass parameters, on the mechanical properties and microstructure were investigated.

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.