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This article addresses an investigation of the influence of plastic deformation on low temperature surface hardening by gaseous nitriding of three commercial austenitic stainless steels: AISI 304, EN 1.4369 and Sandvik Nanoflex® with various degrees of austenite stability. The materials were plastically deformed to different equivalent strains by uniaxial tension. Gaseous nitriding of the strained material was performed in ammonia gas at atmospheric pressure at 703 K (430 °C) and 693 K (420 °C) depending on the material. Microstructural characterization of the as-deformed states and the nitrided case included X-ray diffraction analysis, reflected light microscopy and microhardness. The results demonstrate that a case of expanded austenite develops and that, in particular, strain-induced martensite has a large influence on the nitrided zone. ▪

Background/Objectives:The current world-wide obesity epidemic partially results from a vicious circle whereby maternal obesity during pregnancy predisposes the offspring for accelerated weight gain and development of metabolic syndrome. Here we investigate whether low-grade inflammation, characteristic of the obese state, provides a causal role for this disastrous fetal programming in mice.Methods:We exposed pregnant and lactating C57BL/6JBom female mice to either high-fat diet (HFD), or continuous infusion of lipopolysaccharide (LPS), a potent trigger of innate immunity, and studied offspring phenotypes.Results:Both maternal LPS or HFD treatments rendered the offspring hyperphagic and inept of coping with a HFD challenge during adulthood, increasing their adiposity and weight gain. The metabolic effects were more pronounced in female offspring, while exposed male offspring mounted a larger inflammatory response to HFD at adulthood.Conclusions:This supports our hypothesis and highlights the programming potential of inflammation in obese pregnancies.

The synchrotron-based technique of 3DXRD/HEDM has proven a powerful tool to investigate individual grains in the bulk of a polycrystal during plastic deformation. Comparisons between such experimental data and crystal plasticity simulations typically show agreement with respect to overall qualitative trends. However, comparisons at the level of individual grains are in general less successful. Experimental observations and crystal plasticity simulations for a number of representative grains are analysed for similarities and differences in order to elucidate the origin of these. The comparison points at insufficient modelling of grain interactions, hardening and possibly also in the handling of ambiguities. Spatially resolved experimental data on the orientation spread is expected to provide the information needed to improve the predictive capacity at the level of individual grains.

Dietary protein restriction in pregnant females reduces offspring birth weight and increases the risk of developing obesity, type 2 diabetes and cardiovascular disease. Despite these grave consequences, few studies have addressed the effects of preconceptional maternal malnutrition. Here we investigate how a preconceptional low-protein (LP) diet affects offspring body mass and insulin-regulated glucose metabolism. Ten-week-old female mice (C57BL/6JBom) received either an LP or isocaloric control diet (8% and 22% crude protein, respectively) for 10 weeks before conception, but were thereafter fed standard laboratory chow (22.5% crude protein) during pregnancy, lactation and offspring growth. When the offspring were 10 weeks old, they were subjected to an intraperitoneal glucose tolerance test (GTT), and sacrificed after a 5-day recovery period to determine visceral organ mass. Body mass of LP male offspring was significantly lower at weaning compared with controls. A similar, nonsignificant, tendency was observed for LP female offspring. These differences in body mass disappeared within 1 week after weaning, a consequence of catch-up growth in LP offspring. GTTs of 10-week-old offspring revealed enhanced insulin sensitivity in LP offspring of both sexes. No differences were found in body mass, food intake or absolute size of visceral organs of adult offspring. Our results indicate that maternal protein restriction imposed before pregnancy produces effects similar to postconceptional malnutrition, namely, low birth weight, catch-up growth and enhanced insulin sensitivity at young adulthood. This could imply an increased risk of offspring developing lifestyle-acquired diseases during adulthood.

The influence of the hardness of martensite and ferrite phases in dual phase steel on void formation has been investigated by in situtensile loading in a scanning electron microscope. Microstructural observations have shown that most voids form in martensite by evolving four steps: plastic deformation of martensite, crack initiation at the martensite/ferrite interface, crack propagation leading to fracture of martensite particles and void formation by separation of particle fragments. It has been identified that the hardness effect is associated with the following aspects: strain partitioning between martensite and ferrite, strain localisation and critical strain required for void formation. Reducing the hardness difference between martensite and ferrite phases by tempering has been shown to be an effective approach to retard the void formation in martensite and thereby is expected to improve the formability.

The potential of creating nanostructured metals by plastic deformation to very high strains is currently the subject of intensive research. An important part of this research concerns evolution of the characteristics of deformation induced boundaries, in particular boundary spacing and boundary misorientation. The aim of this paper is to give an overview of the present understanding of the relations between these characteristics, the microscopic deformation mechanisms and the macroscopic deformation mode.

The potential of creating nanostructured metals by plastic deformation to very high strains is currently the subject of intensive research. An important part of this research concerns evolution of the characteristics of deformation induced boundaries, in particular boundary spacing and boundary misorientation. The aim of this paper is to give an overview of the present understanding of the relations between these characteristics, the microscopic deformation mechanisms and the macroscopic deformation mode.

Some of the dislocation boundaries in cold deformed f.c.c. metals at low and intermediate strains lie on crystallographic slip planes and others have a macroscopic direction with respect to the sample axes (i.e. they are non-crystallographic). A model for the occurrence of the former type of dislocation boundaries is proposed. The model combines slip pattern analysis and dislocation theory. It is assumed (i) that the dislocations in the boundaries are generated by slip, (ii) that the deformation temperature is low enough to exclude dislocation climb and (iii) that the driving force for formation of boundaries is minimisation of the energy stored in the boundaries. Formation of crystallographic boundaries is predicted if two active slip systems in the same slip plane account for a large fraction of the total slip. For single crystals the agreement between predicted and experimentally observed crystallographic and non-crystallographic boundaries is excellent. For different grain orientation in poly crystalline aluminium specimens, the agreement between prediction and experiment is satisfactory in view of the complexity of polycrystal studies compared to studies of single crystals.