A Novel Mo and Nb Microalloyed Medium Mn TRIP Steel with Maximal Ultimate Strength and Moderate Ductility

The multi-phase, metastable, and multi-scale (M3) constitution of a novel transformation-induced plasticity (TRIP) steel (Fe-0.17C-6.5Mn-1.1Al-0.22Mo-0.05Nb, wt pct) was designed through thermodynamic calculations combined with experimental analysis. In this study, Mo and Nb microalloying was used to control the fraction of retained austenite and its mechanical stability during tensile deformation and to improve the yield strength. Thermodynamic calculations were developed to determine the critical annealing temperature, at which a large fraction of retained austenite (~38 pct) would be obtained through the effects of solute enrichment. The experimental observation was in good agreement with the predicted results. According to the critical annealing temperature, such an ultrafine (<200 nm) M3, microstructure with optimum mechanical stability was successfully achieved. The results of this work demonstrated the superior performance with improved yield strength of 1020 to 1140 MPa and excellent ductility (>30 pct), as compared with other TRIP steels. Both angle-selective backscatter and electron backscatter diffraction techniques were employed to interpret the transformation from the deformed martensitic laths to the ultrafine austenite and ferrite duplex structure.

Characterization of microstructures and tensile properties of TRIP-aided steels with different matrix microstructure

Three different heat treatment processes have been proposed as a fundamental method to produce three kinds of TRIP-aided steels with polygonal ferritic matrix (F-TRIP), bainitic matrix (B-TRIP) and martensitic matrix (M-TRIP) in a newly designed low alloy carbon steel. By means of dilatometry study and detailed characterization, the relationships among transformation, microstructure and the resulting mechanical behavior were compared and analyzed for the three cases. The work hardening of the samples was evaluated by calculating the instantaneous n value as a function of strain. The M-TRIP sample exhibits the highest strength with the highest work hardening rate at low strains and subsequent rapid descending at high strains. In contrast, the B-TRIP sample has relatively high continuously constant work hardening behavior over strain levels greater than 0.067. The difference in work hardening behavior corresponds directly to the rate of the retained austenite-martensitic transformation during straining, which can be attributed to the carbon content, the morphology of the retained austenite and the matrix microstructure in the respective TRIP-aided samples. © 2014 Elsevier B.V.

Variation in body condition during the post-moult foraging trip of southern elephant seals and its consequences on diving behaviour

Mature female southern elephant seals (Mirounga leonina) come ashore only in October to breed and in January to moult, spending the rest of the year foraging at sea. Mature females may lose as much as 50% of their body mass, mostly in lipid stores, during the breeding season due to fasting and lactation. When departing to sea, post-breeding females are negatively buoyant, and the relative change in body condition (i.e. density) during the foraging trip has previously been assessed by monitoring the descent rate during drift dives. However, relatively few drift dives are performed, resulting in low resolution of the temporal reconstruction of body condition change. In this study, six post-breeding females were equipped with time-depth recorders and accelerometers to investigate whether changes in active swimming effort and speed could be used as an alternative method of monitoring density variations throughout the foraging trip. In addition, we assessed the consequences of density change on the swimming efforts of individuals while diving and investigated the effects on dive duration. Both descent swimming speed and ascent swimming effort were found to be strongly correlated to descent rate during drift dives, enabling the fine-scale monitoring of seal density change over the whole trip. Negatively buoyant seals minimized swimming effort during descents, gliding down at slower speeds, and reduced their ascent swimming effort to maintain a nearly constant swimming speed as their buoyancy increased. One per cent of seal density variation over time was found to induce a 20% variation in swimming effort during dives with direct consequences on dive duration.

Multi-phase microstructure design of a novel high strength TRIP steel through experimental methodology

The multi-phase structure of a novel low-alloy transformation induced plasticity (TRIP) steel was designed through experimental analysis. The evolutions of both microstructure and mechanical properties during the two-stage heat treatment were analyzed. The phase transformations during the intercritical annealing and the isothermal bainitic transformation were investigated by means of dilatometry. It was shown that two types of C diffusion were detected during intercritical annealing and a complex microstructure was formed after heat treatment. The processing parameters were selected in such a way to obtain microstructures with systematically different volume fractions of ferrite, bainite and retained austenite. The volume fractions of ferrite and retained austenite were found to be two main factors controlling the ductility. Furthermore, a high volume fraction of C-rich retained austenite, which was stabilized at room temperature, was the origin of a TRIP effect. The resulting material demonstrates a significant improvement in the ultimate tensile strength (1077. MPa) with good uniform elongation (22.5%), as compared to conventional TRIP steels. © 2014 Elsevier B.V.

Thermo-mechanical processing of TRIP-aided steels

The effects of the partial replacement of Si with Al and the addition of P on the microstructure and mechanical properties of experimental TRIP-aided steels subjected to different thermo-mechanical cycles were studied. Based on the available literature and thermodynamics-based calculations, three steels with different compositions were designed to obtain optimum results from a relatively low number of experiments. Different combinations of microstructure were developed through three different kinds of thermo-mechanical-controlled processing (TMCP) routes, and the corresponding tensile properties were evaluated. The results indicated that partial replacement of Si with Al improved the strength-ductility balance along with providing an improved variation in the incremental change in the strain-hardening exponent. However, the impact of the P addition was found to depend more on the final microstructure obtained by the different TMCP cycles. It has also been shown that an increase in the volume fraction of the retained austenite ($$ V_{{\gamma_{\text{ret}} }} $$Vγret) or its carbon content ($$ C_{{\gamma_{\text{ret}} }} $$Cγret) resulted in an improved strength-ductility balance, which can be attributed to better exploitation of the TRIP effect.

Eight very vary(s): towards a program of mistakes-on-purpose

In 2007, I spent eight weeks in Residency at the Architectural body Research Foundation (Houston Street, NY, NY) with Arakawa and Madeline. In addition to discussion current projects, meeting researcher practitioners and students who would come by the office or talking to people on the phone who had just written or done something of interest, reviewing texts and discussing pressing ideas, Madeline had started work on an Encyclopaedia of Mistakes prompted by the mistakes on Purpose procedure. Every afternoon we would spend three hours or more at the end of the day working on the spectrum and placement of mistakes on the spectrum, lists of mistakes and refinement of what the role of mistakes might be across the organism-person-surround and the potential for perceptual knowing. As the work is an unfinished 31 page manuscript, I will not cite it directly but rather speak about it and the thinking process that went into the many many versions and amendments that produced in February and March of 2007.

Pedagogy and ePortfolios: purpose aligned to design (or the why and how)

While research surrounding ePortfolios abounds, few studies make explicit the pedagogical underpinnings of their use. Some suggest that the decision to use new technologies, like ePortfolios, is often made in ignorance of pedagogic evidence. Developed over the course of a two-year national study on the implementation of ePortfolios, this paper argues the importance of a considered approach to ePortfolio use; one that is premised on carefully linking the purpose and context to the type of portfolio. The paper explores the potential of ePortfolios as they align with four specific pillars of learning: learning to know, learning to do, learning to live together and learning to be. It discusses the pedagogic underpinnings – that is, the why – of ePortfolios including: skills and competencies; transformative potential; reflection; identity; active learning; employability; and assessment. The succeeding section provides recommendations for practical ePortfolio use – that is, the how – and an original framework linking ePortfolio purpose to design is proposed.

Dependence of deformation behavior on grain size and strain rate in an ultrahigh strength-ductile Mn-based TRIP alloy

A novel ultra-high strength TRIP (transformation induced plasticity) steel, with ~1.5. GPa strength and good ductility of ~26% has been produced. The microstructure consists of ultrafine ferrite, and a large volume fraction of austenite. The flow stress was significantly increased by a reduction in the grain size, but the effect of strain rate on the flow stress was negligible. The formation of stress induced martensite was found to increase linearly with strain, and a reduction in the grain size correlated with an increase in the stress required to form the martensite.

Standard setting in specific-purpose language testing: what can a qualitative study add?

This paper explores the views of nursing and medical domain experts in considering the standards for a specific-purpose English language screening test, the Occupational English Test (OET), for professional registration for immigrant health professionals. Since individuals who score performances in the test setting are often language experts rather than domain experts, there are possible tensions between what is being measured by a language test and what is deemed important by domain experts. Another concern is a lack of qualitative research on the process of the standard setting. To date, no published qualitative work has been identified about the contributions of domain experts in the standard setting for healthcare communication. In this study, a standard-setting exercise was conducted for the speaking component of the OET, using judgements of nursing and medical clinical educators and supervisors. In all, 13 medical and 18 nursing clinical educators and supervisors rated medical and nursing candidate performances respectively. These performances were audio-recorded OET role-plays that were selected across a range of proficiency levels. Domain experts were invited to comment on the basis of their decisions and the extent of alignment between these decisions and the criteria used to assess performance on the OET. Nursing and medical domain experts showed that they attended to all of the OET criteria in making their decisions about standards. However, clinical scenario simulation also invited judgements of clinical competence from participants, even where they knew that clinical competence should be excluded from their decision-making. Another concern related to the authenticity limitations of the role-play tasks as evidence of readiness to handle communication in the workplace. Overall, findings support the value of qualitative evidence from the standard setting in providing insight into the factors informing and impeding decision-making.

Creativity: transgression or higher purpose

Modernity is characterized by the fragmentation of our social world, desacralization of institutional life and the relativisation and individualization of our moral perspectives. Such processes undermine and destabilize our sense of shared common values in a society.

School autonomy as ‘the way of the future’: Issues of equity, public purpose and moral leadership

This paper presents interview data from research conducted in two public high schools in the state of Queensland, Australia. The research was concerned with exploring issues of equity and diversity. Both schools had recently converted to ‘independent’ status within a new state policy reform – the Independent Public Schools initiative. This reform was seen as having a significant effect on matters of equity and diversity and so became an important focus of the research. Within current accountability parameters, there were concerns expressed by key personnel at the schools about how converting to an Independent Public Schools was both enabling and constraining student equity in terms of resource distribution and school access, and undermining schools’ focus on their public purpose in relation to imposing an excessive focus on narrow external accountability measures. These concerns bring to light the significance of moral leadership within autonomous schooling environments – shaped as they are by regimes of accountability and competition that can clearly compromise student equity and delimit schooling purposes.

Field ‘work’ vs ‘feel’ trip : approaches to out-of-class experiences in geography education

Fieldwork is viewed as integral to geography teaching and acclaimed benefits often include holistic, student-driven learning, where all the senses are engaged and the impacts are more than cognitive. While these benefits are often assumed, in this paper, I argue that geography fieldwork in schools is often teacher-led and focused on the intellectual task of knowledge acquisition and skill development. Based on a qualitative content analysis of examples of fieldwork in a state geography teachers’ journal, I assert that the affective and sensory dimensions, are often used to promote the benefits of fieldwork, but seldom explicitly addressed through fieldwork pedagogy and learning activities in school geography. I contend that this is a missed opportunity for a deeper, more embodied and critical engagement with, and response to, the places visited.