Production, Bonding and Application of Metal Matrix Composite Hot Forging Tool Components

Metal matrix composite materials are of high interest for their increased stiffness, strength or wear resistance. Wear resistant composites contain hard ceramic particles to reduce microcutting and grooving of the metal matrix surface. In this paper, a gas atomised hot work tool steel X40CrMoV5-1 (1.2344/AISI H13) was combined with fused tungsten carbide (FTC) particles in order to create forging tools with increased abrasive wear resistance. For that purpose, tool components were manufactured by sinter-forging of stacked powder layers to build up a graded hard phase concentration of up to 10 vol.-%. Subsequently, sinter-forged specimens were combined with basic hot work tool steel components and joined by diffusion bonding to assemble the complete tool. In order to evaluate their performance, the tools were examined in a hot backward can extrusion process of low-alloyed steel. Optical geometry measurements, light microscopy and scanning electron microscopy of the worn tool radii indicated a significant decrease in abrasive wear when using FTC-reinforced tools rather than conventional hardened tool steel

Commodity tax competition and industry location under the destination- and the origin-principle

We develop a model of commodity tax competition with monopolistically competitive internationally mobile firms, transport costs, and asymmetric country sizes. We investigate the impacts of non-cooperative tax setting, as well as of tax harmonization and changes in the tax principle, in both the short and the long run. The origin principle, when compared to the destination principle, is shown to exacerbate tax competition and to erode tax revenues, yet leads to a more equal spatial distribution of economic activity. This suggests that federations which care about spatial inequality, like the European Union, face a non-trivial choice for their tax principle that goes beyond the standard considerations of tax revenue redistribution.commodity tax competition, origin principle, destination principle, tax harmonization, industry location

О возможности использования индуктивного параметрона для защиты от замыканий на землю в сетях с изолированной нейтралью

Показана возможность использования индуктивного параметрона как реагирующего органа в защитах от замыканий на землю в сетях с изолированной нейтралью. Защита с параметроном является селективной и равночувствительной, обладает достаточной чувствительностью

Advective timescales and pathways of Agulhas leakage

Current research indicates an increase in Agulhas leakage for the past and coming decades. This change potentially alters the strength of the Atlantic meridional overturning circulation, in particular, through advection of positive density anomalies into the North Atlantic. To explore the fate of Agulhas leakage, results from a Lagrangian analysis were evaluated, with virtual floats advected within an eddy-permitting ocean model (ORCA025). A considerable fraction of Agulhas leakage reached the subtropical North Atlantic: of a mean Agulhas leakage transport of 15.3 Sv entering the South Atlantic, 9.7, 7.7, and 6.1 Sv crossed sections at 6 degrees S, 6 degrees N, and 26 degrees N, respectively. The most probable transit time of leakage to reach the respective latitudes is one to two decades. We suggest that changes in Agulhas leakage could manifest in the Gulf Stream regime most probably within two decades. These results were supported by an eddy-resolving implementation of the ocean model (INALT01

A micro-volume adaptation of a stopped-flow system; use with μg quantities of muscle proteins

Stopped-flow spectroscopy is a powerful method for measuring very fast biological and chemical reactions. The technique however is often limited by the volumes of reactants needed to load the system. Here we present a simple adaptation of commercial stopped-flow system that reduces the volume needed by a factor of 4 to ≈120 μl. After evaluation the volume requirements of the system we show that many standard myosin based assays can be performed using <100 μg of myosin. This adaptation both reduces the volume and therefore mass of protein required and also produces data of similar quality to that produced using the standard set up. The 100 μg of myosin required for these assays is less than that which can be isolated from 100 mg of muscle tissue. With this reduced quantity of myosin, assays using biopsy samples become possible. This will allow assays to be used to assist diagnoses, to examine the effects of post translational modifications on muscle proteins and to test potential therapeutic drugs using patient derived samples

Tailored Forming of hybrid bulk metal components

Multi-material bulk metal components allow for a resource efficient and functionally structured component design, with a load adaptation achieved in certain functional areas by using similar and dissimilar material combinations. One possibility for the production of hybrid bulk metal components is Tailored Forming, in which pre-joined semi-finished products are hot-formed using novel process chains. By means of Tailored Forming, the properties of the joining zone are geometrically and thermomechanically influenced during the forming process. Based on this motivation, forming processes (die forging, impact extrusion) coupled with adapted inductive heating strategies were designed using numerical simulations and successfully realised in the following work in order to produce demonstrator components with serial or coaxial material arrangements. The quality of the joining zone was investigated through metallographic and SEM imaging, tensile tests and life cycle tests. By selecting suitable materials, it was possible to achieve weight savings of 22% for a pinion shaft and up to 40% for a bearing bush in the material combination of steel and aluminium with sufficient strength for the respective application. It was shown that the intermetallic phases formed after friction welding barely grow during the forming process. By adjusting the heat treatment of the aluminium, the growth of the IMP can also be reduced in this process step. Furthermore, for steel-steel components alloy savings of up to 51% with regard to chromium could be achieved when using low-alloy steel as a substitute for high-alloy steel parts in less loaded sections. The welded microstructure of a cladded bearing washer could be transformed into a homogeneous fine-grained microstructure by forming. The lifetime of tailored formed washers nearly reached those of high-alloyed mono-material components

Casting manufacturing of cylindrical preforms made of low alloy steels

The manufacturing of complex drivetrain components made of steel requires multi-stage manufacturing processes, resulting in long processing times and high costs. Forged parts get their final geometry after multi-stage forming operations. One approach to shorten such process chains is close contour casting of steel preforms and a single subsequent forming step to achieve high strength properties similar to those of multi-stage forged parts. Since the application of precision forging using cast steel preforms has been studied insufficiently up to now, the manufacturing of cylindrical preforms made of the low-alloy heat-treatable steel G42CrMo4 by sand casting was investigated. Using casting simulations, suitable casting parameters for the finished casting systems were identified and nearly pore-free preforms were achieved. Depending on the casting system, metallographic investigations revealed different fractions of bainite in the microstructure of the casted preforms. Subsequently, the cylinders were deformed in upsetting experiments by which the remaining porosity could be eliminated. The numerical casting simulation was combined with a forming simulation to model the reduction in porosity and to allow the prediction of the densification behavior in further research employing more complex geometries