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In this study, the corrosion behavior of AISI 304 fuel rail brazed joints in presence of ethanolic E85 fuel has been evaluated. The galvanic corrosion resulting from coupling steel and copper brazing alloys has been studied as it represents a potential risk for the functionality of the fuel rail and injectors. The corrosion can lead to nozzle clogging by the increase of level of solute metallic ions or rupture of the joint itself. Tests have been carried out both on specimens simulating the brazed joints and on real fuel rail component. Static immersion tests and static filling tests in standard gasoline, E85 and modified E85 fuels have been carried out. The latter have been prepared by adding aggressive reagent, such as acetic acid, sulfuric acid, and chlorides, to the E85 fuel. Tests have been carried out at room temperature and at 60 °C. Alternative brazing materials to copper alloys (nickel- and silver-based alloys) have also been tested, with the aim of comparing their corrosive resistance. From results here obtained, the nickel-based brazing alloys, which have been tested because of their intrinsic ability to passivate, have proved to be more resistant to corrosion than copper, but only during exposure to commercial E85 and at room temperature. Silver-based brazing alloys have shown poor resistance to corrosion and the tendency of soluted Ag ions to precipitate in presence of chloride ions. [ABSTRACT FROM AUTHOR]

Laser beam welding of dissimilar AISI 440C and AISI 430F stainless steels was investigated in a circular constrained configuration. The beam incidence angle and the offset of the focusing position respect to the contact point between the two materials were used as main control parameters to vary the melting ratio inside the seam. The objective of the study is twofold: to avoid surface microcracks related to the high percentage of carbon of the martensitic steel and to enhance the shear strength of the weld by making it less brittle. To reach this scope the effects of incidence angle and offset on weld bead geometry and melting ratio were studied by means of metallographic analyses, microstructure and microhardness characterization. As last step, the weld mechanical strength was tested by tensile-shear stress test on the whole seam. Experiments demonstrated that varying incidence angle and offsetting the focal position is a reliable method to modify the melting ratio and maintaining the expected resistance length at the material interface, as well. It was found that increasing the percentage of ferritic steel into the joint has beneficial effects on the weld quality and on the shear resistance. The critical carbon content determining the mechanical properties in the fusion zone can be calculated by taking into account the melting ratio. [ABSTRACT FROM AUTHOR]

Vitis vinifera ssp. silvestris, the spontaneous subspecies of V. vinifera L., is believed to be the ancestor of present grapevine cultivars. In this work, polymorphism at 13 SSR loci was investigated to answer the following key question: are wild plants (i) true silvestris, (ii) hybrids between wild and cultivated plants or (iii) or ‘escapes’ from vineyards? In particular, the objective of the present study was to identify truly wild individuals and to search for possible hybridization events. The study was performed in Sardinia, the second largest island in the Mediterranean Sea, which is characterized by a large and well-described number of both grape cultivars and wild populations. This region was ideal for the study because of its spatial isolation and, consequently, limited contamination from outside material. The results of this study show that domesticated and wild grapevine germplasms are genetically divergent and thus are real silvestris. Pure lineages (both domesticated and wild) show very high average posterior probabilities of assignment to their own clusters, with a low level of introgression. [ABSTRACT FROM AUTHOR]

Electromagnetic induction surveys are among the most popular techniques for non-destructive investigation of soil properties, in order to detect the presence of both ground inhomogeneities and particular substances. This paper introduces a MATLAB package, called FDEMtools, for the inversion of frequency domain electromagnetic data collected by a ground conductivity meter, which includes a graphical user interface to interactively modify the parameters of the computation and visualize the results. Based on a non-linear forward model used to describe the interaction between an electromagnetic field and the soil, the software reconstructs the distribution of either the electrical conductivity or the magnetic permeability with respect to depth, by a regularized damped Gauss–Newton method. The regularization part of the algorithm is based on a low-rank approximation of the Jacobian of the non-linear model. The package allows the user to experiment with synthetic and experimental data sets, and different regularization strategies, in order to compare them and draw conclusions. [ABSTRACT FROM AUTHOR]

Hydrogen Re-Embrittlement on anodically coated high strength steels is a relevant risk for aerospace structures due to the possibility of hydrogen uptake during the operative life of the components. AISI 4340 and Maraging 250 unnotched tensile specimens were subjected to SSRT in order to evaluate the influence of test environment on time to failure. Fracture surfaces were examined by SEM analysis to evaluate the degree of embrittlement and to correlate it with hydrogen diffusivity of the tested steels. [ABSTRACT FROM AUTHOR]

Abstract: The aim of the present paper is to propose an innovative hydrogenation method based on metal hydride dissociation. By heating metal hydride, high pressure of molecular hydrogen is generated, which can be used to promote diffusion through the steel, resulting in very high atomic hydrogen concentration. This new hydrogenation method was tested on a F82H steel, a Reduced Activation Ferritic/Martensitic (RAFM) steel developed for nuclear fusion application, where high temperature Hydrogen Embrittlement (HE) is a matter of serious concern. The main goal of this study is to propose a methodology to perform tensile tests on steel at high temperature and high hydrogen contents. The technique is easy and cheap. Furthermore, by using different metal hydrides and tuning temperatures, different hydrogen concentrations can be tested. [Copyright &y& Elsevier]