Formation of ultra-fine ferrite in hot rolled strip: potential mechanisms for grain refinement

A novel single-pass hot strip rolling process has been developed in which ultra-fine (<2 μm) ferrite grains form at the surface of hot rolled strip in two low carbon steels with average austenite grain sizes above 200 μm. Two experiments were performed on strip that had been re-heated to 1250°C for 300 s and air-cooled to the rolling temperatures. The first involved hot rolling a sample of 0.09 wt.%C–1.68Mn–0.22Si–0.27Mo steel (steel A) at 800°C, which was just above the Ar3 of this sample, while the second involved hot rolling a sample of 0.11C–1.68Mn–0.22Si steel (steel B) at 675°C, which is just below the Ar3 temperature of the sample. After air cooling, the surface regions of strip of both steel A and B consisted of ultra-fine ferrite grains which had formed within the large austenite grains, while the central regions consisted of a bainitic microstructure. In the case of steel B, a network of allotriomorphic ferrite delineated the prior-austenite grain boundaries throughout the strip cross-section. Based on results from optical microscopy and scanning/transmission electron microscopy, as well as bulk X-ray texture analysis and microtextural analysis using Electron Back-Scattered Diffraction (EBSD), it is shown that the ultra-fine ferrite most likely forms by a process of rapid intragranular nucleation during, or immediately after, deformation. This process of inducing intragranular nucleation of ferrite by deformation is referred to as strain-induced transformation.

Enhanced tensile ductility of an ultra-fine-grained aluminium alloy

Aluminum alloy 6082 was subjected to equal-channel angular pressing (ECAP), which resulted in an ultra-fine-grained (UFG) microstructure with an average grain size of 0.2–0.4 μm. There was a pronounced effect of the grain refinement on the strain-rate sensitivity and tensile ductility. The Hart criterion of tensile necking fails to explain the observed ductility of the UFG material at low strain rates. A correlation between the observed stronger-than-expected ductility and a tendency to microshear band formation at low strain rates was established.

Deformation behaviour of an ultra-fine grained Al6082 alloy

This work focuses on the effect of strain rate on the deformation behaviour of an ultrafine grained Al alloy 6082 produced by equal channel angular  pressing. The uniform tensile elongation was found to increase with  decreasing strain rate very substantially. This effect is discussed in terms of the mechanisms that control plastic deformation of the alloy.

Cost implications of specific and non-specific treatment for young persons at ultra high risk of developing a first episode of psychosis

Aim: Costs associated with mental health treatment for young persons at 'ultra' high risk (UHR) of developing a psychotic disorder have not previously been reported. This paper reports cost implications of providing psychological and pharmacological intervention for individuals at UHR for psychosis compared with minimal psychological treatment.

Method: Mental health service costs associated with a randomized controlled trial of two treatments (Specific Preventive Intervention: SPI and Needs-Based Intervention: NBI) for UHR young persons were estimated and compared at three time points: treatment phase, short-term follow up and medium-term follow up.

Results: Although the SPI group incurred significantly higher treatment costs than the NBI group over the treatment phase, they incurred significantly lower outpatient treatment costs over the longer term.

Conclusion: This study indicates that specific interventions designed to treat young persons who are identified as being at UHR of psychosis might be associated with some cost savings compared with non-specific interventions.

Processing and quality of cashmere tops for ultra-fine wool worsted blend fabrics

This study has focussed on three main areas. First, an evaluation of the physical attributes of cashmere tops available to commercial spinners; second, the influence of processing variables on the efficiency of producing cashmere tops from raw Australian cashmere; and third, the influence of design of cashmere ultrafine wool blends on the fibre curvature of tops. Testing the physical attributes of cashmere tops from traditional and new sources of supply, was followed by statistical analyses based on factors of origin, processor and other determinants. The analyses demonstrated important processor effects and also that cashmere from different origins shows commercially important variations in fibre attributes. It was possible to efficiently produce Australian cashmere tops with Hauteur, tenacity, extension, softness and residual guard hairs quality attributes equivalent to those observed in the best cashmere tops. The blending of cashmere with wool resulted in a reduction of the mean fibre curvature of the blend compared with the unblended wool. The present work demonstrated that the fibre curvature properties of blended low crimp ultrafine wool tops were closer to the properties of pure cashmere tops than were tops made from blended standard high crimp ultrafine wool. The attributes of textiles made from the relatively rare Australian low curvature cashmere could enhance the marketability of both Australian cashmere and low curvature wool.

Development of a novel micro-spray-assembly process for multilayer ultra-thin film formation

A novel micro-spray-assembly process and an automatic device to fabricate multilayer ultra-thin film are introduced. Employing self-assembly monolayer (SAM) technique, ultra-thin film can be assembled by utilizing the micro-spray-assembly device. The thickness and roughness of each monolayer can be controlled by varying various materials attributes, i.e., deposition time, ionic strength, pH value, molecular concentration and by selecting different manufacturing parameters of the automatic device such as spraying rate, size of micro-drop, N₂ flow rate, temperature of N₂ flow.

The effect of strain rate on the deformation mechanisms and the strain rate sensitivity of an ultra-fine-grained Al alloy

An ultra-fine-grained Al alloy was subjected to compression tests at different strain rates. The strain rate sensitivity of the flow stress was estimated. A strong effect of the baseline strain rate on the mechanisms of plastic deformation was found. It is suggested that a decrease of strain rate results in activation of micro shear banding due to grain boundary sliding. A connection between the strain rate, strain rate sensitivity, and the prevalent deformation mechanism was established.

Basic symptoms in young people at ultra high-risk of psychosis

Basic Symptoms are cognitive and emotional disturbances characteristic of the early stage of psychosis. This study established the utility of an instrument to identify Basic Symptoms amongst young people at high-risk for developing psychosis, thereby facilitating the pathway to treatment for these individuals. The portfolio focuses on how having an unwell parent contributes to and influences the development of psychopathology in offspring. The four clinical case studies are presented in detail, and the intervention strategies for each individual are evaluated.

Deformation mechanisms in an ultra-fine grained Al alloy

This work focuses on the deformation behavior of an ultra-fine grained Al-Mg-Si alloy processed by equal channel angular pressing over a wide range of temperatures and strain rates. The effect of temperature and strain rate on the homogeneity of plastic deformation, the evolution of microstructure, the strain rate sensitivity and the underlying deformation mechanisms are investigated. It is demonstrated that the localization of plastic deformation at the micro scale is triggered by grain boundary sliding due to grain boundary sliding due to grain boundary diffusion. The contributions of different deformation mechanisms during the plastic deformation of the material are discussed.

Machinability assessment and surface integrity characteristics of Austempered Ductile Iron (ADI) using ultra-hard cutting tools

The application of austempered ductile iron (ADI) is gaining an ever greater share of the worldwide ferrous product market, specifically centering on the aerospace, automotive and shipping industries. ADI is a heat treated cast iron, which exhibits remarkable mechanical properties and provides an attractive material for designers and engineers to displace conventional materials. Previous attempts, however, to machine ADI using carbide or ceramic cutting tools produced poor tool life characteristics due to the relatively poor machinability of the workpiece. This paper presents a research study that has applied the advanced technology of modern ultrahard cutting tools, in an attempt to achieve enhanced machinability performance. This performance was evaluated through the analysis of cutting forces, tool wear, surface finish and roundness.