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Two ferrous laminated composites containing six layers have been processed by roll bonding. One of them consists of three layers of an ultrahigh carbon steel (1.3%C UHCS) interlayered with other three layers of a microalloyed steel. The other composite consists of three layers of UHCS and three layers of a mild steel. Microstructure, Vickers hardness and impact properties have been studied. The absorbed energy values of the two laminated composites were higher than that of the UHCS.Se procesaron mediante laminación en caliente dos materiales compuestos laminados de acero de ultraalto contenido de carbono (AUAC, 1,3%C) de seis capas cada uno: El primero está compuesto por tres capas de AUAC alternadas con tres capas de un acero microaleado, y el segundo con tres del mismo AUAC alternadas con tres de un acero suave. Se ha realizado un estudio de sus microestructuras, dureza Vickers y propiedades de impacto. Se han mejorado los valores de energía absorbida de los dos materiales compuestos laminados respecto al del AUAC.

Rotylenchulus reniformis is one of the most important nematode pests of cotton. Currently, no cotton cultivar resistant cotton cultivar to this pest is available. In the framework of a breeding program aiming at producing cotton genotype resistant to this nematode, a R. reniformis resistance evaluation protocol based on egg inoculation, extraction and counting, has been established. Two environment conditions (growth chamber and greenhouse), four sieves (75, 50, 20 and 10 µm), three doses of inoculum (1,500; 3,000 and 6,000 eggs), and five durations of infestation (20, 30, 40, 50 and 60 days after inoculation) have been tested. The growth chamber programmed to provide 12 h of light, 55%-60% relative humidity and 30-26°C day-night air temperatures revealed to be adequate. The NaOCl (sodium hypochloride)-blender-sieving-centrifugation-flotation method, using 75-µm and 20-µm sieves, kaolin powder and MgSO4 (magnesium sulfate) solution (specific gravity 1.18) proved to be suitable for effective R. reniformis egg extraction (from roots) and counting. Inoculation of 6,000 eggs per seedling and 60 days duration of infestation seemed to be sufficient dose and period for a reliable resistance evaluation. The protocol developed has been tested on known susceptible and resistant cotton genotypes: G. hirsutum L (main cultivated species through the world, susceptible), G. thurberi Tod. (wild cotton species, moderately susceptible) G. longicalyx Hutch. and Lee (wild cotton species, very resistant). The results obtained were in accordance with the response expected from the genotypes tested, proving the reliability of the evaluation procedure developed.

In this paper, novel protection techniques against soft errors for adaptive filters are presented. The new techniques are based on the use of system knowledge in terms of both filter structure and functionality, as well as the application tolerance to soft errors. Adaptive filters by nature recover from soft errors on their coefficients, but in existing implementations the recovery time can exceed what is acceptable for many applications. The proposed techniques dramatically reduce the recovery time after a soft error with an acceptable increment on circuit complexity, as they rely on reusing existing logic. To illustrate these techniques, a case study is presented in which their effectiveness is evaluated using a software-based fault injection platform. Also, their complexity is estimated in terms of the number of equivalent gates generated for the synthesized circuit implementation using a commercial ASIC library. Index Terms--Adaptive filters, digital filters, radiation hardening, redundancy, single event upsets (SEUs).

Single Event Effects (SEEs) caused by radiation are a major concern when working with circuits that need to operate in certain environments, like for example in space applications. In this paper, new techniques for the implementation of moving average filters that provide protection against SEEs are presented, which have a lower circuit complexity and cost than traditional techniques like Triple Modular Redundancy (TMR). The effectiveness of these techniques has been evaluated using a software fault injection platform and the circuits have been synthesized for a commercial library in order to assess their complexity. The main idea behind the presented approach is to exploit the structure of moving average filter implementations to deal with SEEs at a higher level of abstraction. Index Terms--Digital filters, radiation hardening, redundancy, Single Event Upsets (SEUs).

The 7075 alloy is an Al-Zn-Mg-Cu wrought age-hardenable aluminum alloy widely used in the aeronautical industry. The alloy was accumulative roll bonded at 300 °C (573 K), 350 °C (623 K), and 400 °C (673 K), and the microstructure, texture, and hardness were investigated. Cell/(sub)grain size in the nanostructured range, typical β-fiber rolling texture, and homogeneous hardness through thickness were determined in all cases. Misorientation was different at each processing temperature. At 400 °C, the presence of elements in solid solution and the partial dissolution of the hardening precipitates lead to a poorly misoriented microstructure with a high dislocation density and a homogeneous β-fiber texture of low intensity, typical of intermediate degrees of rolling. At 350 °C and 300 °C, highly misoriented microstructures with smaller dislocation density and intense heterogeneous β-fiber rolling texture are observed, especially at 350 °C, wherein the degree of dynamic recovery (DRV) is higher. Hardness of the accumulative roll bonded samples is smaller than that of the starting material due to particle coarsening, and it is affected by solid solution and/or by fine precipitates produced by reprecipitation of the elements in solid solution. [ABSTRACT FROM AUTHOR]

A new method, Rieiro, Carsí, Ruano (RCR), for solving the Garofalo equation is developed. This method is based on an integrated algorithm that allows determination of the equation parameters for any given material and does not need initial values. The RCR method is used to analyse the Garofalo equation best fit applied to torsion data at various temperatures and strain rates from a (V-N) microalloyed steel. The predictive capability of the RCR method on experimental results is ~6% in stress and the magnitude of the predicted errors is of the same order as the interpolation errors. On the other hand, the n value is slightly lower and the Q value slightly higher than those expected for a slip creep mechanism controlled by lattice diffusion. However, the obtained values agree with those found in the literature for microalloyed steels. These differences can be attributed to microstructure changes during deformation. [ABSTRACT FROM AUTHOR]

Interface toughness for delamination has been determined in a laminate composite consisting of Fe-0.9Cr-0.5Mo steel layers. Three point bend tests were used to evaluate the critical energy release rate Gc for delamination under elastic linear and plane strain conditions. A value of Gc of 2.8 kJ m-2 was obtained which is considerably lower than the energy for crack propagation across the layer. The given Gc corresponds to a critical stress intensity factor Kc of 25 MPa m1/2. These low values are responsible of delamination and, therefore, of the 34% improvement in toughness of the laminate with regard to the monolithic material. [ABSTRACT FROM AUTHOR]

The article presents a study which examines the microstructure evolution during recrystallization of newly developed low nickel, high manganese-nitrogen austenitic stainless steels. The researchers prepared three new steels based on the system Fe-18Cr-15Mn-2Ni-2Mo-XN, and evaluated their microstructure. The study reveals a good correlation between texture and microstructure evolution during annealing, and demonstrates the randomization of the texture during recrystallization of the austenite.

The microstructure and the mechanical properties of a multilayer composite laminate based on aluminum 7075 and 2024 alloys produced by hot roll bonding were examined. The composite laminate has been tested at room temperature under Charpy-impact tests, three-point bend tests, and shear tests on the interfaces. The toughness of the post-rolling tempered and T6-treated composite laminate, measured by impact- absorbed energy in the crack-arrester orientation, was more than 20 times higher than that of the monolithic Al 7075 alloy and 7 times higher than that of Al 2024 alloy. The outstanding toughness increase of the composite laminate in the post-rolling tempered and T6-treated condition is mainly due to the mechanism of “interface predelamination.” By this fracture mechanism, the interfaces are debonded before the main crack reaches them, warranting delamination in all interfaces. Therefore, delamination and crack renucleation in every layer are responsible for the improvement in toughness. [ABSTRACT FROM AUTHOR]

The influence of fluctuations in the grain size along the gauge length on ductility is analysed in the superplastic regime. It is demonstrated that these fluctuations produce a similar effect to that produced by variations in the initial uniformity of the sample, leading to premature necking. To reach superplastic elongations of 400%, fluctuations in grain size of <0·5% between two zones of the gauge length are required. As an example, the superplastic behaviour of an AZ61 alloy, processed by severe plastic deformation (SPD), with a heterogeneous microstructure is analysed when the grain boundary sliding mechanism controls deformation. It is found that neck formation is related to bands of fine grains that are formed during SPD processing by the mechanism of recrystallisation by rotation. Under these circumstances, grain refinement is rendered unsuccessful. The present investigation emphasises the importance of the microstructure homogeneity in developing grain refinement processing routes. [ABSTRACT FROM AUTHOR]

The aim of this paper is to study the influence of the initial microstructure of several Mg–Al alloys on their superplastic formability and on their post-forming microstructure and mechanical properties. Various thermomechanical processing routes, such as annealing, conventional rolling, severe rolling and cross rolling, were used in order to fabricate AZ31 and AZ61 alloys with different grain sizes. These materials were then blow formed into a hat shaped die. It was found that the processing route has only a small effect in the formability of Mg–Al alloys or on the post-forming microstructures and properties due to rapid dynamic grain growth taking place at the forming temperatures. Nevertheless, good formability is achieved as a result of the simultaneous operation of grain boundary sliding and crystallographic slip during forming. [ABSTRACT FROM AUTHOR]