Jurisdiction over a Parent Corporation in Its Subsidiary\u27s State of Incorporation

In this paper we examine how Spanish language marks a political divide within the Latino community. Spanish language use also provides an opportunity for political parties to send slightly different campaign messages. We illustrate this point with reference to California’s Democratic part

Failure mode analysis on compression of lattice structures with internal cooling channels produced by laser powder bed fusion

Conformal cooling coils have been developed during the last decades through the use of additive manufacturing (AM) technologies. The main goal of this study was to analyze how the presence of an internal channel that could act as a conformal cooling coil could affect compressive strength and quasi-elastic gradient of AlSi10Mg lattice structures produced by laser powder bed fusion (LPBF). Three different configurations of samples were tested in compression at 25 °C and 200 °C. The reference structures were body centered cubic (BBC) in the core of the samples with vertical struts along Z (BCCZ) lattices in the outer perimeter, labelled as NC samples. The main novelty consisted in inserting a straight elliptical channel and a 45° elliptical channel inside the BCCZ lattice structures, labelled as SC and 45C samples respectively. All the samples were then tested in as-built (AB) condition, and after two post process heat treatments, commonly used for AlSi10Mg LPBF industrial components, a stress relieving (SR) and a T6 treatment. NC lattice structures AB exhibited an overall fragile fracture and therefore the SC and 45C configuration samples were tested only after thermal treatments. The test at 25 °C showed that all types of samples were characterized by negligible variations in their quasi-elastic gradients and yield strength. On the contrary, the general trend of stress-strain curves was influenced by the presence of the channel and its position. The test at 200 °C showed that NC, SC and 45C samples after SR and T6 treatments exhibited a metal-foam like deformation

Influence of focus offset on the microstructure of an intermetallic gamma-TiAl based alloy produced by electron beam powder bed fusion

It is well established in literature that, when processing intermetallic gamma-TiAl components by electron beam powder bed fusion, a banded microstructure is frequently formed because of an inhomogeneous Al distribution since more pronounced evaporation of Al occurs at the top of the melt pool. This feature is particularly promoted when highly energetic process parameters (high beam currents, slow beam speeds, narrow line offsets) are used. Therefore, an approach already suggested in the literature to reduce the Al loss is to minimize the energy level of the process parameter during production. However, there is a limit to such kind of approach: minimizing the beam current or increasing the beam speed, or increasing the line offset will, at a certain point, results in not being able to achieve a completely dense material and thus some process -induced porosity, the so-called lack-of-fusion defects, starts to occur in the produced parts.In this study, the effect of an additional parameter of the electron beam powder bed fusion process is taken under consideration: the focus offset (FO), i.e. the distance between the focusing plane of the electron beam with respect to the powder bed. The effect of the FO on the residual porosity, microstructure, phase composition, hardness as well as chemical composition is investigated, thus having the possibility to demonstrate that also the FO can affect the Al loss and play a fundamental role in the generation of a homogenous microstructure, contributing to mitigate the appearance of a banded microstructure

Role of the chemical homogenization on the microstructural and mechanical evolution of prolonged heat-treated laser powder bed fused Inconel 625

Ni-based superalloy components for high-temperature applications rely on the long term stability of the microstructure and mechanical properties at service temperatures. Nowadays, the production of such types of components is frequently performed via Additive Manufacturing (AM) technologies. Nevertheless, few studies are dedicated to understanding the behavior of AM Ni-based superalloys upon prolonged exposure to high temperatures. This work aims at studying the effect of prolonged thermal exposures on the microstructure and mechanical properties of Inconel 625 processed by laser powder bed fusion. Thermal exposures within the range of 600 °C and 900 °C for 200 h were performed on this material. The as-built and solution annealed Inconel 625 conditions were selected. The solution annealed state implies a complete chemical homogenization, typically recommended for working at high temperatures, whereas the initial as-built state is characterized by segregations and fine dendritic structures. Upon the studied prolonged thermal exposures, the peculiar as-built microstructure formed a higher quantity of phases with smaller dimensions with respect to the solution annealed condition under thermal exposures. The smaller phases of the as-built state resulted in similar mechanical properties evolution under different temperatures. Differently, the prolonged heat-treated solution annealed conditions exhibited more marked mechanical properties variations due to coarser phases

Caratterizzazione ad usura di rivestimenti PVD con e senza laser texturing

Il processo di laser texturing (LST) è una delle tecniche più promettenti nel campo delle microlavorazioni superficialiin quanto consente di ottenere un eccellente controllo della forma e delle dimensioni delle microcavitàprodotte ed è estremamente veloce e senza ricadute dannose per l’ambiente. Recentemente si è assistito allosviluppo di diversi lavori nei quali il laser è stato impiegato per migliorare il comportamento tribologico di componentimeccanici in materiale metallico. Le microcavità, realizzate per ablazione dal fascio laser sulla superficiedi interesse, infatti hanno diversi aspetti positivi da questo punto di vista perché generano un sistema diffusodi microspinte idrodinamiche sulla superficie e agiscono come riserve di lubrificante da una parte e come trappoleper i detriti di usura dall’altra, ritardando così, l’innesco di meccanismi di usura da terzo corpo. Nel presentelavoro si presentano i risultati di una sperimentazione volta a valutare l’effetto dell’introduzione di unalavorazione superficiale di texturing laser sulla superficie di riporti PVD in TiN. Per il texturing è stata utilizzatauna sorgente laser in fibra innovativa ad alta efficienza che ha consentito, una volta ottimizzati i parametridi processo, di ottenere dimensioni controllate delle microcavità, una buona geometria delle stesse e di evitarela presenza di residui di lavorazione anche sui coating ceramici oggetto dello studio. I test di usura in condizionidi strisciamento lubrificato con alto carico applicato e bassa velocità relativa , sono stati condotti sul rivestimentoTiN microlavorato e per confronto sul tal quale e su un rivestimento autolubrificante commerciale,il WC/C. I risultati ottenuti mostrano un marcato incremento delle prestazioni a usura per il rivestimento lasercon texturing (fino al 50% di riduzione del volume di usura) e l’assenza di significativi danneggiamenti del rivestimentoin presenza delle microcavità e delle sollecitazioni di usura applicate. Nel breve futuro si eseguiràpertanto un approfondimento ulteriore per valutare anche l’economia di scala del ciclo di lavorazione

Net shape HIPping of a Ni-superalloy: A study of the influence of an as-leached surface on mechanical properties

Hot Isostatic Pressing (HIP) is a net-shape powder metallurgy technique where powders densification is achieved through the application of high temperature and pressure at the same time. Powders are allocated into a hollow steel mold called capsule or canister which gives the final shape to the particles. This technique is particularly useful for manufacturing complex components made of materials which are extremely difficult to process via forging or casting. Thus, HIP is particularly indicated to handle superalloy powders such as Astroloy, which is the object of the following study. One of the most attractive peculiarities of HIP is the low material waste obtained since the overstock is limited to the layers immediately beneath the steel capsule. At the end of the HIP cycle, the canister is typically removed using an acid leaching bath which is responsible for the alteration of the outermost layers of the final product. Only a little number of research papers deal with the optimization of the removal of these layers; Consequently, manufacturers often apply a very conservative approach by eliminating more material than is actually needed with a final machining procedure. This paper aims to optimize this procedure by systematically assessing the total thickness of the altered layer of material deriving from the HIPping and leaching process together. To achieve this goal, a set of samples were prepared by removing progressively thicker layers of material and then they were bend tested. Finally, the recorded mechanical properties were compared with those obtained with the samples machined from the core material. One of the main findings is that the removal of 500 μm of material is enough to recover mechanical properties which are comparable with those observed in samples coming from the core. More specifically, by eliminating the first 100 μm material, all the corroded layer is removed, which results in an overall increase of all the mechanical properties except for ductility. This property strongly depends on the number of prior particle boundaries arising from the HIPping process itself. Thus, the correct amount of overstock material must include both these layers

Prediction of the critical load of a metal-rolling system by considering the damage of the coated surface

Under various working conditions, rolling elements may suffer from different types of damage behaviour, including fractures in the coatings and bonding interfaces, and plastic deformation in the substrate materials. The present paper reports research into the prediction of the critical load of a metal-rolling system (metal-rolling system) by considering the damage of the coated surface based on a novel FE simulation-procedure developed by the present authors. The modelling procedure features several modelling approaches including: parameterised FE modelling, Cohesive-Zone modelling and a sub-modelling technique. The typical case examined in this study is linecontact between two cylindrical bodies. The studied surface-modified systems are CrN, TiN and TiN/CrN multilayer PVD coatings applied on 42CrMo4 steel in both the nitrided and quenched-and-tempered states. It was observed through the numerical simulation that for almost all of the configurations, cracking occurs at the edge of the contact when one cylinder is pressing against the other cylinder, due to a bending effect. The critical load of the system was determined by referring to the initiation of the first crack of the coated surface of the ring. Comparison between the numerical-simulation results and the experimental results showed excellent agreement

Information-rich quality controls prediction model based on non-destructive analysis for porosity determination of AISI H13 produced by electron beam melting

The number of materials processed via additive manufacturing (AM) technologies has rapidly increased over the past decade. As of these emerging technologies, electron beam powder bed fusion (EB-PBF) process is becoming an enabling technology to manufacture complex-shaped components made of thermal-cracking sensitive materials, such as AISI H13 hot-work tool steel. In this process, a proper combination of process parameters should be employed to produce dense parts. Therefore, one of the first steps in the EB-PBF part production is to perform the process parameter optimization procedure. However, the conventional procedure that includes the image analysis of the cross-section of several as-built samples is time-consuming and costly. Hence, a new model is introduced in this work to find the best combination of EB-PBF process parameters concisely and cost-effectively. A correlation between the surface topography, the internal porosity, and the process parameters is established. The correlation between the internal porosity and the melting process parameters has been described by a high robust model (R-adj(2) = 0.91) as well as the correlation of topography parameters and melting process parameters (R-adj(2) = 0.77-0.96). Finally, a robust and information-rich prediction model for evaluating the internal porosity is proposed (R-adj(2) = 0.95) based on in situ surface topography characterization and process parameters. The information-rich prediction model allows obtaining more robust and representative model, yielding an improvement of about 4% with respect to the process parameter-based model. The model is experimentally validated showing adequate performances, with a RMSE of 2% on the predicted porosity. This result can support process and quality control designers in optimizing resource usage towards zero-defect manufacturing by reducing scraps and waste from destructive quality controls and reworks