Response of A356 to warm rotary forming and subsequent T6 heat treatment

The through-process microstructural effects in A356 subjected to rotary forming at elevated temperatures have been investigated. Macro and micro-hardness testing have been used extensively to track changes in the material from the as-cast state to as-formed, and T6 heat treated. Targeted thermal treatments have been used to isolate the effects of mechanical deformation through comparative measurements. These measurements include macro and micro hardness measurements, Energy-dispersive X-ray analysis and examination of eutectic-Si particle size and morphology. The results indicate that the as-cast material is stable up to approximately 144{\deg}C, with the rotary formed material exhibiting decreased macrohardness in-line with the time spent at elevated temperature. Post heat treatment, there was a significant decrease in hardness with increased levels of deformation. Results indicate that precipitation hardening is not appreciably affected by rotary forming, and the principal cause for the drop in hardness with deformation is due to the condition of Al-Si eutectic phase.Comment: 26 pages, 13 figure

Analysis and modelling of a rotary forming process for cast aluminum alloy A356

Spinning of a common aluminum automotive casting alloy A356 (Al-7Si-0.3 Mg) at elevated temperatures has been investigated experimentally with a novel industrial-scale apparatus. This has permitted the implementation of a fully coupled thermomechanical finite element model aimed at quantifying the processing history (stress, strain, strain-rate and temperature) and predicting the final geometry. The geometric predictions of this model have been compared directly to the geometry of the workpieces obtained experimentally. This study is novel in regards to both the size and shape of the component as well as the constitutive material representation employed. The model predictions are in reasonable agreement with experimental results for small deformations, but errors increase for large deformation conditions. The model has also enabled the characterization of the mechanical state which leads to a common spinning defect. Suggestions for improving the accuracy and robustness of the model to provide a predictive tool for industry are discussed

Molecular mechanisms of vaspin action: from adipose tissue to skin and bone, from blood vessels to the brain

Visceral adipose tissue derived serine protease inhibitor (vaspin) or SERPINA12 according to the serpin nomenclature was identified together with other genes and gene products that  were specifically expressed or overexpressed in the intra abdominal or visceral adipose tissue  (AT) of the Otsuka Long-Evans Tokushima fatty rat. These rats spontaneously develop visceral  obesity, insulin resistance, hyperinsulinemia and ‐glycemia, as well as hypertension and thus represent a well suited animal model of obesity and related metabolic disorders such as type  2 diabetes.  The follow-up study reporting the cloning, expression and functional characterization of  vaspin suggested the great and promising potential of this molecule to counteract obesity induced insulin resistance and inflammation and has since initiated over 300 publications, clinical and experimental, that have contributed to uncover the multifaceted functions and molecular mechanisms of vaspin action not only in the adipose, but in many different cells, tissues and organs. This review will give an update on mechanistic and structural aspects of vaspin with a focus on its serpin function, the physiology and regulation of vaspin expression, and will summarize the latest on vaspin function in various tissues such as the different adipose tissue depots as well as the vasculature, skin, bone and the brain

An infrared spectroscopic (IR) and light element (Li, Be, Na) study of cordierites from the Bamble Sector, south Norway

Infrared absorption spectra and light element contents of several natural cordierites across the Arendal amphibolite-granulite facies transition, Bamble Sector, south Norway are presented. The infrared spectra record HO (both type-I and type-II) and CO as fluid constituents in the channels, CO and hydrocarbons were not detected. Type-II water and (Ca+Na+K) are correlated and show a 2:1 molar ratio. The infrared and light element data indicate a decrease of Na, type-II HO, CO and Li with metamorphic grade, while type-I HO and Be are variable. The decrease of these volatiles and alkalies and the low total volatile contents of the granulite facies cordierites are best explained by progressive dehydration and decarbonation processes, possibly related to partial melting. A progressive change of the X= HO (HO+CO) ratio in the cordierites across the transition, as suggested by previous studies, is not observed. Greenschist to low-amphibolite facies re-equilibrated cordierites show a significant increase in either CO, or HO+CO. Na is introduced at some localities. The retrograde fluid phase is calculated to be CO-rich

Development of a 3D Filling Model of Low-Pressure Die-Cast Aluminum Alloy Wheels

Extended Abstract Today, the need of high quality cast components for automotive and aeronautics industries leads to develop the lowpressure casting process This work proposes a characterization of the imposed gas pressure -metal flow velocity relationship in low pressure casting. More precisely, the relative effect of local and global horizontal section changes on filling flow is studied. To do so, experimentally measured and numerically predicted metal front position evolutions are compared in the case of different mould geometries. An AlSi 13 alloy is melt and poured by low pressure casting in 3D printed sand moulds. A 25mbar/s pressure ramp is set for filling. Three different geometries are studied with an identical global horizontal section restriction of 0.24: one cylinder, six cylinders and one ring. To track the experimental metal height evolution, electrical contacts are used. Experimental metal height versus time curves are extracted and reveal an oscillating phenomenon after section changing. Due to this phenomenon, an over-height which is not predicted by the analytical equations is observed. The velocity of the flow reaches values above 0.5m/s, leading to risks of defects. The experimental cases are then simulated using ANSYS Fluent® simulation software. A k-epsilon flow model simulates the whole low pressure systemthe metal in the mould, in the tube and in the furnace and the pressuring gas-. The observed filling oscillations are compared to the oscillations predicted by the model in terms of maximal overweight and velocity for the three studied geometries. A relationship between local and global horizontal section restriction factor and oscillations is proposed. It will allow us to define reliable rules of mould design for limiting turbulence and reaching sound quality in low pressure casting