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A Study Of Grain Size Effect On Mechanical Behaviour, Fracture Mechanism, Texture Evolution And Springback In Microforming Process, Zhi Fang

University of Wollongong Thesis Collection 1954-2016

Size effects play a significant role in microforming process, and any dimensional change on microstructure or specimens can have a great impact on materials’ mechanical properties. In this research, the grain size effect on deformation behaviour, fracture and grain orientation of phosphor bronze foil are investigated in the form of the ratio of materials’ thickness (T) to average grain size (D) by micro tensile tests. The ratio is designed to be greater than, less than and equal to 1 respectively. The results show that the amount of plastic deformation decreases with the decrease of the ratio T/D, which indicates the …

Lubrication Mechanics Of Inorganic Polyphosphate In Ferrite Strip Rolling Of Interstitial Free Steel, Ning Kong

University of Wollongong Thesis Collection 1954-2016

This thesis aims to investigate the tribological behaviours of the rubbing steel/steel pairs with a proposed polyphosphate lubricant at the temperatures of ferrite rolling and the effect of lubrication on the texture of interstitial free (IF) steel which is rolled in the ferrite temperature range. As complex tribological reactions at the sliding interface depend on the high load and temperature conditions, the thesis will provide a better insight into the possible tribochemical reactions of the given polyphosphate lubricant system which can reduce friction and wear, minimise oxidation, improve surface quality and texture for better drawability.

The flow stress and pyroplastic …

Crystal Plasticity Finite Element Method Simulation Of Equal Channel Angular Pressing, Guanyu Deng

University of Wollongong Thesis Collection 1954-2016

Severe plastic deformation (SPD) has been the subject of intensive investigations in recent years because of the unique physical and mechanical properties of ultrafine grained (UFG) materials fabricated by this technique. Equal channel angular pressing (ECAP) is the most frequently used SPD technique due to its efficiency in grain refinement. The deformation mechanism during the ECAP process is very complicated and it has always been assumed to be a simple shear along the intersecting plane of two ECAP channels in most published literatures. A number of experiments and numerical simulations have revealed that the simple shear based theory could not …

Study On Hydride Precipitation And The Induced Embrittlement Behaviours In Zircaloy-4, Zhiyang Wang

University of Wollongong Thesis Collection 1954-2016

The zirconium alloy, Zircaloy-4 (Zr-4), has extensive applications in the nuclear industry as core structural components and fuel claddings in the nuclear reactors. The mechanical performance of these components can be strongly affected by the precipitation of brittle zirconium hydrides and the induced embrittlement. This work investigated the hydride precipitation behaviours in different Zr-4 materials with various thermo-mechanical states (i.e. the high-pressure torsion (HPT) processed disk, hot-rolled and annealed plate, and hot-extruded and annealed bar). The effect of hydride formation on the mechanical properties of Zr-4 materials was also studied.

A comparative study was conducted to clarify the effect of …

Microstructure, Texture And Vacancy-Type Defects In Severe Plastic Deformed Aluminium Alloys, Lihong Su

University of Wollongong Thesis Collection 1954-2016

Severe plastic deformation (SPD) as a technique to process ultrafine grained (UFG) materials has attracted significant interest over recent years. Equal channel angular pressing (ECAP) and accumulative roll bonding (ARB) are two of the most important SPD techniques. Despite that many studies have been conducted on both techniques, some research areas have still not been explored deeply, such as the influence of low pressing temperature on ECAP, the deformation behaviour of the same material in monotonic material sheets or laminated composite sheets during ARB and the evolution of point defects during SPD. The present work investigates the microstructure, mechanical properties, …

A Study Of Surface Roughness In The Metal Forming Process, H J. Li

University of Wollongong Thesis Collection 1954-2016

Surface roughness affects surface quality and wear and fatigue of metal forming products. The objective of this study is to improve our understanding of the evolution of surface asperity (surface roughness) during cold uniaxial planar compression of aluminium samples. Experimental research and simulation analysis were applied to study the evolution of surface asperity during compression.

Uniaxial planar compression experiments of FCC (Face Centred Cubic) aluminium alloy have been carried out using the designed compressing equipment on an INSTRON 8033 Material Testing Machine to examine the characteristics of surface asperity during compression. These characteristics have been investigated by instruments such as …

Recrystallisation In A Rapidly Annealed Low Cost Β-Titanium Alloy, Quoc Viet Vu

University of Wollongong Thesis Collection 1954-2016

This study investigates the recrystallisation behaviour of cold drawn low cost beta (LCB) Ti-1.5Al-6.8Mo-4.5Fe-0.2O (wt.%) by tracking the evolution of its microstructure and microtexture during rapid resistance annealing. The studied material was solution treated at 850^oC for 1800 s, followed by water quenching, then cold-drawn at room temperature to 80% (CD80) and 90% (CD90) reduction in diameter and consequently rapid resistance heating to select peak temperatures at rates of 10 and 20^oC.s-1. All aspects of the present study have been characterised using advanced Electron Back-Scattering Diffraction (EBSD) and X-ray diffraction techniques. The EBSD maps were deconstructed …

Recrystallisation And Deformation Behaviour Of Twinning Induced Plasticity (Twip) Steel, Ahmed A. Saleh

University of Wollongong Thesis Collection 1954-2016

TWinning Induced Plasticity (TWIP) steels with low stacking fault energy and stable face centred cubic austenitic microstructures have been developed as a promising material for automotive applications due to their characteristic work hardening behaviour. The present work investigates the recrystallisation and deformation behaviours of Fe-24Mn-3Al-2Si-1Ni-0.06C TWIP steel using various diffraction techniques and polycrystal plasticity modelling.

After 42% cold rolling reduction, transmission electron microscopy and electron backscattering diffraction (EBSD) found that a majority of grains contain a large fraction of primary twin densities and a smaller fraction of intersecting arrangements of primary and secondary twins. Bulk texture measurements using X-ray diffraction …