Precipitate characterisation of an advanced high-strength low-alloy (HSLA) steel using atom probe tomography

Increased fuel economy, combined with the need for the improved safety has generated the development of new hot-rolled high-strength low-alloy (HSLA) and multiphase steels such as dual-phase or transformation-induced plasticity steels with improved ductility without sacrificing strength and crash resistance. However, the modern multiphase steels with good strength-ductility balance showed deteriorated stretch-flangeability due to the stress concentration region between the soft ferrite and hard martensite phases [1]. Ferritic, hot-rolled steels can provide good local elongation and, in turn, good stretch-flangeability [2]. However, conventional HSLA ferritic steels only have a tensile strength of not, vert, similar600 MPa, while steels for the automotive industry are now required to have a high tensile strength of not, vert, similar780 MPa, with excellent elongation and stretch-flangeability [1]. This level of strength and stretch-flangeability can only be achieved by precipitation hardening of the ferrite matrix with very fine precipitates and by ferrite grain refinement. It has been suggested that Mo [3] and Ti [4] should be added to form carbides and decrease the coiling temperature to 650 °C since only a low precipitation temperature can provide the precipitation refinement [4]. These particles appeared to be (Ti, Mo)C, with a cubic lattice and a parameter of 0.433 nm, and they were aligned in rows [4]. It was reported [4] that the formation of these very fine carbides led to an increase in strength of not, vert, similar300 MPa. However, the detailed analysis of these particles has not been performed to date due to their nanoscale size. The aim of this work was to carry out a detailed investigation using atom probe tomography (APT) of precipitates formed in hot-rolled low-carbon steel containing additions Ti and Mo.

The investigated low-carbon steel, containing Fe–0.1C–1.24Mn–0.03Si–0.11Cr–0.11Mo–0.09Ti–0.091Al at.%, was produced by hot rolling. The processing route has been described in detail elsewhere [5] European Patent Application, 1616970 A1, 18.01.2006.[5]. The microstructure was characterised by transmission electron microscopy (TEM) on a Philips CM 20, operated at 200 kV using thin foil and carbon replica techniques. Qualitative energy dispersive X-ray spectroscopy (EDXS) was used to analyse the chemical composition of particles. The atomic level of particle characterisation was performed at the University of Sydney using a local electrode atom probe [6]. APT was carried out using a pulse repetition rate of 200 kHz and a 20% pulse fraction on the sample with temperature of 80 K. The extent of solute-enriched regions (radius of gyration) and the local solute concentrations in these regions were estimated using the maximum separation envelope method with a grid spacing of 0.1 nm [7]. A maximum separation distance between the atoms of interest of dmax = 1 nm was used.

The microstructure of the steel consisted of two types of fine ferrite grains: (i) small recrystallised grains with an average grain size of 1.4 ± 0.2 μm; and (ii) grains with a high dislocation density (5.8 ± 1.4 × 1014 m−2) and an average grain size of 1.9 ± 0.1 μm in thickness and 2.7 ± 0.1 μm in length (Fig. 1a). Some grains with high dislocation density displayed an elongated shape with Widmanstätten side plates and also the formation of cells and subgrains (Fig. 1a). The volume fraction of recrystallised grains was 34 ± 8%.

Global social justice at the WTO? The role of NGOs in constructing global social contracts

Over the past decade, international non-governmental organizations (NGOs) have been contesting the neo-liberal economic order in international politics by campaigning for normative conditions to bring about what Richard Falk calls 'humane governance'. However, the degree to which NGOs have contributed to the formation of global social contracts remains controversial. While NGO activists and various scholars advocate the establishment of such contracts, empirical testing of this normative argument is underdeveloped. Drawing upon this lack of empirical support, critics dismiss the global social contract concept and question the roles played by NGOs in international politics. This article addresses the controversy through a review, refinement and application of global social contract theory and an empirical study of two prominent international NGO campaigns directed at the World Trade Organization (WTO), an institution that represents a 'hard test case'. It explores the ways in which NGOs and their networks are challenging the neo-liberal basis of WTO agreements and contributing to the emergence of global social contracts. The article concludes that in some circumstances, NGOs have the capacity to inject social justice into international economic contracts and there is some basis for optimism regarding the formation of global social contracts involving NGOs, nation-states and international organizations.

Grain size in Mg alloys: recrystallization and mechanical consequences

The present paper examines the development of grain size during the recrystallization of magnesium alloys and the influence the grain size has on the mechanical response. In magnesium alloys grain refinement improves the strength-ductility balance. This simultaneous increase in both strength and ductility is ascribed to the impact the grain size has on deformation twinning. The mechanisms by which the grain size is established during hot working are shown to be conventional dynamic recrystallization followed by post-dynamic recrystallization. The role of alloying additionon both of these reactions is briefly considered.

Dynamic adjustment of ferrite grains during dynamic strain induced transformation

The dynamic adjustment of ferrite grains formed during 'dynamic strain induced transformation (DSIT)' is an important feature of this mechanism that has not been addressed previously. A novel experimental method was applied to follow the effect of deformation at different stages on ferrite formed initially through DSIT. It is shown that while the continuous dynamic recrystallisation (CDRX) appears to be an acceptable mechanism for re-refinement of coarser grain size (i.e. dα>2dDSIT), it cannot explain the steady state grain size for finer ferrite grains (i.e. dα<2dDSIT). Other potential mechanisms involved in this phenomenon are examined.

Modeling of the mechanical behavior of nanostructured HSLA steels

In the present paper the basic strengthening mechanisms operating in microstructures are discussed with respect to their application in submicron/nano materials. This analysis focuses on these strengthening mechanisms in bcc microstructures, where the effect of grain boundaries is very strong. An experimental study of the influence of the thermomechanical history on the microstructure and dislocation substructure was performed using two different grades of HSLA steels. As a result, a modified version of the Khan–Huang–Liang flow stress model (KHL) was developed and is discussed in the light of results from the present study. Comparison with experimental results showed significant diversity in the refinement and mechanical responses of each steel, due to different activity of strengthening mechanisms and microalloying elements in the microstructure evolution process. The effect of mechanical and microstructural inhomogeneity in severe plastic deformation (SPD) on the deformation induced grain refinement and mechanical properties was also considered.

A physical based modeling approach for the dynamic behavior of ultrafine grained structures

This paper discusses some experimental results on the influence of grain refinement on the final mechanical properties of IF and microalloyed steels designed for auto-body components. It shows also some modeling approaches to understanding the dynamic behavior of fine-rained materials. The Zerilli–Armstrong (Z–A) and Khan–Huang–Liang (KHL) models for studied steels were implemented into FEM code in order to simulate the dynamic compression tests with different strain rates.

Injury prevention during physical activity in the Australian Defence Force

Introduction:
Injuries sustained by Australian Defence Force (ADF) personnel during non-combat military training and sports activity are associated with increasing costs due to work days lost, medical treatment, compensation, and early retirement. In 2001, the ADF commissioned a systematic review of the evidence-base for reducing injuries associated with physical activity, while at the same time improving physical activity participation rates to sustain a trained, fit and deployable workforce.

Method:
Literature from on-line library databases, relevant unclassified military reports, and material from previously published sport-specific injury countermeasure reviews were systematically and critically analysed to address the study aims.

Results:
Modification of intensity, frequency and duration of basic military training activities and improved equipment is likely to reduce injury occurrence. Sports injury countermeasures used for the civilian population have merit for the ADF physical activity program. Injury countermeasures should be designed to minimise any possible deterrent effect on the motivation to participate in regular physical activity. Increasing the participation of ADF personnel in physical activity in the presence of evidence-based injury prevention strategies has the potential to increase health, fitness and deployability with minimal impact on injury frequency.

Conclusion:
Recommendations arising from the review include injury intervention trials in basic military training and sports. These and other interventions should be supported by refinement to ADF injury surveillance systems. Research should focus on interventions with the greatest gain for fitness, deployability, and cost effectiveness.

Integration of an internet-driven supply chain for a medium-size e-commerce company

This research aimed at discovering the benefits and challenges of integration across a company's e-supply chain. The research involved a single case study of an Australian e-commerce company. In our work, we first formed a framework of benefits and challenges for e-supply chain integration, which was based on the beliefs held by management consultants. After conducting interviews with various organisational stakeholders of an e-commerce company, we found that although some of the elicited opinions matched those expressed by consultants, others provided their refinement in respect to a medium size, rapidly evolving, start-up company. We also discovered challenges, seemingly ignored by the consultants, which concerned changing market conditions and limited economies of scale perceived as seriously impeding SCM integration. Also, the ability to develop and maintain scalable and effective information systems was found to impact the capacity to integrate services across the e-supply chain. The case study's single most important contribution was to bring to our attention the importance of organisational and environmental maturity in the strategic planning of the supply chain management process.

Equity-focused health impact assessment framework

Background to the Development of the Equity-Focused HIA Framework
The equity focused health impact assessment (EFHIA) framework arises out of a two year research project funded for the most part by the Australian Government’s Public Health Education Research Program (PHERP) Innovations Grants (Round 2) scheme. This project had as its primary objective the development of a framework for health inequalities impact assessment, subsequently renamed equity focused health impact assessment. A partnership between the University of Newcastle, Deakin University and the University of New South Wales (the Project Management Steering Committee) received the funding and the Australasian Collaboration for Health Equity Impact Assessment (ACHEIA) was formed to undertake appropriate background research and to develop, pilot test, modify and disseminate the framework. The work commenced in September 2002 and concluded in October 2004. Part of the funding included a capacity building workshop in August 2004. ACT Health and the Division of Medicine at the John Hunter Hospital, Newcastle, also provided financial support for the project. The August 2004 Workshop was supported by NSW Health. All participants and organisations involved in the project gave extensive in-kind support.
The aims of the workshop were to bring together an international collaboration of multidisciplinary investigators, public health experts, and key senior health managers working in national, state and local settings, to inform the further development of the framework and to provide training in its application. The initial goals of the project were to work collaboratively to develop a strategic framework to assess the health inequalities of public health-related policies, plans, strategies, decisions, programs and services. The EFHIA framework as presented at the August workshop was developed through:
1. an extensive review of the relevant literature
2. formal and informal consultation with members of ACHEIA (the international
reference group), members of the Project Management Steering Committee and
other relevant experts; and
3. testing of the draft EFHIA framework with the 5 case study partners – who applied the draft framework in a range of health settings (see
Acknowledgements).
The result of this work has been the development of an equity focused health impact assessment framework that can be used to determine the unanticipated and systemic health inequities that may exist within the decision making processes or activities of a range of organisations and sectors. The EFHIA framework provides one approach that can be used to assist decision makers to put equity and health on their agenda in a more obvious and systematic way. The framework represents a ‘moment in time’ rather than a definitive statement or ‘toolkit’ on the best way to proceed. Further practice, refinement and adjustment will be needed over many years to consolidate both HIA and EFHIA. As well as this guide to the framework, additional outputs from the project team include:
- A literature review
- A position paper
- A report on the five case studies
- An evaluation report.
With the consent of the Australian Government, a monograph will be made available to workshop participants at the end of October which contains the framework and the appropriate background papers.

Solidification of cast magnesium alloys

A description of the key solidification steps in the formation of the as-cast microstructure of magnesium alloys is presented. The focus is on the two common magnesium alloy groups: Mg-Al alloys and Mg-Zn-rare earth alloys. The key elements described are: nucleation (including grain refinement), growth of the primary phase and the formation of the eutectic phases. In addition the effect of casting process (e.g. high-pressure diecasting and sand casting) on the outcomes from solidification are discussed. This includes consideration of the formation of banded defects during solidification in the dynamic environment of high pressure die casting.

Ethical perspective on sustainable business practices

This paper considers contemporary business practice and its sustainable performance from the view of stakeholder value. Stakeholder value is a broad concept and implies that a company has responsibilities and commitments to many different internal and external stakeholders in the marketplace and society, not only to its investors and the owners of the company, but also to its employees, customers, suppliers, societies and the environment. This view underlines the need for organisations to, not only provide value, but do so in a sustainable and socially responsible manner.

In considering the stakeholder value perspective of contemporary business practice, the authors proffer that undertaking an ethical perspective in corporate business practices will result in long term sustainable and socially responsible performance that delivers superior stakeholder value. In order to operationalise this concept a model is developed based on five, separate but interconnected, elements: (i) Foundation, (ii) Communication, (iii) Guidance, (iv) Outcome, and (v) Reconnection. The authors emphasise that the model is iterative and acknowledge its elementary state, suggesting further development and refinement in the field of sustainable business practices from an ethical perspective.

Fine grained AZ31 produced by conventional thermo-mechanical processing

The magnesium alloy AZ31 was processed by severe hot rolling and annealing. This processing was optimised to produce recrystallised grain sizes as small as 2.2 μm. The texture of the processed plate was similar to that of the as-received material, with a strong basal alignment in the normal direction. Tensile testing of the fine grained material showed an increase in the strength and elongation compared to the as-received plate. It is  concluded that the improved mechanical properties of the fine grained material results from a refinement in the grain size and the elimination of shear bands that pre-exist in the as-received material.

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.

Dependency of recrystallization mechanism to the initial grain size

The effect of initial grain size on the recrystallization behavior of a type 304 austenitic stainless steel during and following hot deformation was investigated using hot torsion. The refinement of the initial grain size to 8 μm, compared with an initial grain size of 35 μm, had considerable effects on the dynamic recrystallization (DRX) and post-DRX phenomena. For both DRX and post-DRX, microstructural investigations using electron backscattered diffraction confirmed an interesting transition from conventional (discontinuous) to continuous DRX with a decrease in the initial grain size. Also, there were unexpected effects of initial grain size on DRX and post-DRX grain sizes.

Stereo correspondence estimation using multiwavelets scale-space representation-based multiresolution analysis

A multiresolution technique based on multiwavelets scale-space representation for stereo correspondence estimation is presented. The technique uses the well-known coarse-to-fine strategy, involving the calculation of stereo correspondences at the coarsest resolution level with consequent refinement up to the finest level. Vector coefficients of the multiwavelets transform modulus are used as corresponding features, where modulus maxima defines the shift invariant high-level features (multiscale edges) with phase pointing to the normal of the feature surface. The technique addresses the estimation of optimal corresponding points and the corresponding 2D disparity maps. Illuminative variation that can exist between the perspective views of the same scene is controlled using scale normalization at each decomposition level by dividing the details space coefficients with approximation space. The problems of ambiguity, explicitly, and occlusion, implicitly, are addressed by using a geometric topological refinement procedure. Geometric refinement is based on a symbolic tagging procedure introduced to keep only the most consistent matches in consideration. Symbolic tagging is performed based on probability of occurrence and multiple thresholds. The whole procedure is constrained by the uniqueness and continuity of the corresponding stereo features. The comparative performance of the proposed algorithm with eight famous existing algorithms, presented in the literature, is shown to validate the claims of promising performance of the proposed algorithm.