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Graphene Encapsulating Process: A Road Map For Manufacturing Aluminium Matrix Composites With Superior Mechanical Properties, Alireza Fadavi Boostani

University of Wollongong Thesis Collection 1954-2016

Manufacturing aluminium matrix composites with a uniform distribution of the nanoparticles using liquid fabrication methods is a rigorous task, attributed to the high propensity of these nanoparticles to agglomerate.

novel method was proposed in this study for the first time to diminish the agglomeration propensity of SiC nanoparticles using graphene encapsulation process (Chapters 3 and 4). This method was invented based upon two different processing routes, encompassing ball milling and solvo-thermal assisted methods (Chapter 5) to wrap graphene sheets around SiC nanoparticles. As-received and graphene encapsulated SiC nanoparticles were then incorporated into A357 aluminium alloy using semi-solid stir-casting method under …

Fabrication Of Gamma Titanium Aluminide Alloys By Gas Tungsten Arc Welding-Based Additive Layer Manufacturing, Yan Ma

University of Wollongong Thesis Collection 1954-2016

Although intermetallic titanium aluminide alloys have extensive practical industrial applications owing to their unique characteristics, their usage has been limited by the difficulties and high cost of fabrication.

This research proposes an alternative manufacturing approach to fabricating titanium aluminide alloys, which combines in-situ alloying and additive layer manufacturing (ALM) using gas tungsten arc welding (GTAW). This new fabrication process promises significant time and cost saving in comparison to traditional methods. Since the chemical composition, microstructural features and mechanical performance of the asfabricated components can be greatly influenced by the manufacturing parameters, the effect of several important variables including arc current, …

Characterisation Of Ti-6al-4v Deposits Produced By Arc-Wire Based Additive Manufacture, Nicholas Hoye

University of Wollongong Thesis Collection 1954-2016

Significant efforts have been made in recent times to reduce the relatively high cost associated with titanium alloys and hence allow for greater utilisation of the unique properties offered by these materials. One such area of interest is additive manufacturing of components through arc-wire based fusion welding processes. The present thesis details research conducted to characterise aspects of weldability of the Ti-6Al-4V titanium alloy related to this emerging manufacturing process. The resulting properties of the final deposit were also evaluated, with conclusions drawn on the suitability of the arc-wire deposition technique for the additive manufacture of large scale titanium components. …

Deformation Behaviour And Finite Element Method Modelling Of Twinning Induced Plasticity (Twip) Steel, Ching-Tun Peng

University of Wollongong Thesis Collection 1954-2016

TWinning Induced Plasticity (TWIP) steels have been placed as promising materials for the next generation of auto-related materials as well as the military applications due to their exceptional energy absorption ability. The present work investigates the compression and blast behaviour of Fe-18Mn-1.5Al-0.6C TWIP steel using various diffraction techniques and single crystal plasticity finite element method modelling.

The compression behaviour of TWIP steel has been investigated at various strain rates with different strains, including a Split Hopkinson Pressure Bar (SHPB) apparatus, and the results exhibited outstanding strain hardening. This unique feature is ascribed to mechanical twinning occurring during deformation which was …

Microstructure, Crystallography And Mechanical Properties Of Low-Si Trip Steels, Fayez Alharbi

University of Wollongong Thesis Collection 1954-2016

Transformation-­‐induced plasticity (TRIP) steel has received significant research effort because its high strength to ductility ratios and high energy absorption make it eminently suitable for automotive applications. This work investigates the microstructure, crystallography, and mechanical properties of thermo-­mechanically processed (TMP) low-Si high-Al TRIP steels with and without the addition of 0.03Nb and 0.02Ti (wt%) using a combination of optical and electron microscopy, X-ray diffraction, and tensile testing.

The two TRIP steels investigated were subjected to simulated TMP and galvanising and then the results were compared with intercritically annealed–galvanised steels. After undergoing different thermo-­‐mechanical processing schedules it was found that adding …

Structure Property Correlation In The Weld Haz Of High Strength Line Pipe Steels, Zhixiong Zhu

University of Wollongong Thesis Collection 1954-2016

This research investigates the detailed microstructure-mechanical property relationships in the weld heat affected zone (HAZ) of commercially fabricated API 5L grade X70 and X80 line pipe steels. High strength line pipe steels are widely used for the transmission of energy such as crude oil and natural gas and provide an important service. Although the combination of high strength and good toughness can be achieved in the base metal (BM) through the adoption of clean steelmaking, advanced thermomechanical controlled processing (TMCP) technology and tailored alloy design, the welding thermal cycles can dramatically change the properties in the HAZ. Microalloying addition of …

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, …