bluuebunny/crossref_metadata_2025_split huggingface dataset:
Schäden an Brennerkomponenten von Heavy Duty-Gasturbinen
Authors: Neidel Andreas , Matijasevic-Lux Biljana , Riesenbeck Susanne , Ullrich Thomas , Völker Jörg , Wallich Sebastian 
Published: December 2013

Kurzfassung
Brenner sind Schlüsselkomponenten in Turbomaschinen mit interner Verbrennung. Sie ermöglichen in Großgasturbinen für Kraftwerke eine besonders magere Verbrennung und tragen so wesentlich zum wirtschaftlichen Betrieb bei. Abhängig vom Design sind sie häufig statisch und dynamisch hoch beansprucht. Bei der Fertigung dieser sowohl geometrisch als auch werkstofftechnisch komplexen Bauteile spielen schmelzschweisstechnische Fügeverbindungen eine wichtige Rolle. An drei ausgewählten Schadensbeispielen, die mit gerissenen Schweissnähten in Zusammenhang stehen, wird gezeigt, dass fast immer eine Kombination mehrerer Ursachen schadensauslösend wirkt. Besonderer Wert wird dabei auf die Betrachtung konstruktions-, fertigungs-, montage- und betriebsbedingter Einflüsse und Ursachen gelegt. Die als Datenträger wichtigen Bruchflächen der Schadensteile zeigen in den vorgestellten Fällen Schwingbrüche und Heißrisse als werkstofftechnische Versagensmechanismen.
Mechanical and Microstructural Behaviour of Dissimilar Aluminum Alloys Joined by Friction Stir Welding
Authors: Sayer Sami , Yeni Çinar , Kuşoğlu Murat 
Published: December 2013

Abstract
In this study, joining of dissimilar aluminum alloys 5059-H111 and 7075-T651 was carried out using friction stir welding. The joint has been investigated in terms of microstructure, hardness and mechanical properties. Optical microscopy was used to characterize the microstructure of the weld area. Seven different zones of the microstructure in the joint can be distinguished. It has been observed that a fine grain structure is formed in the nugget zone as a result of recrystallization. Although there is a general hardness decrease throughout the weld region compared to both base metals, the lowest hardness values are seen at the heat affected and thermo mechanically affected zones of aluminum alloy 5059. The mechanical strength of the dissimilar joint was found to be varying between 56 % to 68 % those of the base metal ultimate tensile strength values. The results show that friction stir welding can be successfully applied for the joining of dissimilar aluminums alloys.
Effect of Mg on Mechanical Properties of Al-Mg Alloys
Authors: Çaydaş Ulaş , Hasçalik Ahmet 
Published: December 2013

Abstract
In this study, the effect of Mg content on the mechanical properties of Al-Mg alloys was investigated. For this, five different alloys were produced by conventional casting method. Tension, Charpy and fatigue tests were carried out and hardness measurements were conducted on the alloys. Fatigue tests were performed using a rotational bending fatigue test machine and the fatigue strength has been analysed by drawing S-N curves and critically observing fatigue fracture surfaces of the tested samples. The microstructure of the alloys and fracture surfaces were examined by optical and scanning electron microscopy (SEM). The experimental results indicate that mechanical properties are significantly affected by the addition of Mg and the fatigue strength of samples increased due to solid solution strengthening with increasing Mg content in chosen conditions.
Study of Microstructural Evolution of X4CrNiSiTi14-7 During Thermal Aging
Authors: Sakhawat Shahroz , Falahati Ahmad , Domankova Maria 
Published: December 2013

Abstract
Microstructural evolution during aging treatment in a high tensile precipitation hardening stainless steel (X4CrNiSiTi14-7) has been investigated. Matrix consists of martensitic structure and the combined addition of Si and Ti causes an intermetallic phase type Ni16Ti6Si7 that precipitates with-in grains and enhance precipitation strengthening. This material shows a good combination of high strength and ductility.
Light-Optical microscopy, electron back scattered diffraction, transmission electron microscopy and X-ray diffraction analysis have been used to study the microstructural evolution during aging. It has been found that precipitations of various kinds are taking place during aging treatments including nm-scaled G-phase and various carbides. Higher aging temperatures lead to reverse transformation of martensite to austenite.
3D Interpenetrating Hybrid Network of Rigid Phases in an AlSi10Cu5NiFe Piston Alloy
Authors: Asghar Z. , Requena G. , Boller E. 
Published: December 2013

AbstractThe three dimensional architecture of an AlSi10Cu5NiFe piston alloy in as-cast condition is characterized qualitatively and quantitatively by means of synchrotron tomography and light optical tomography. The same sample is used to correlate and combine the results obtained using both techniques. Synchrotron tomography reveals the long-range interconnectivity, volume fraction and shape of different aluminides present in the studied alloy. The morphology of individual aluminides and their contiguity between each other as well as with the eutectic Si is studied by light optical tomography. The eutectic Si and the Fe-aluminides show a considerable fraction of regions with platelet-like morphologies while the Cu-aluminides and Ni-aluminides show a large fraction of region with convex saddle and convex cylindrical morphologies. The aluminides and the eutectic Si form ≈ 18 vol. % three dimensional hybrid network with a long-range contiguity and interconnectivity located in the interdendritic space.
The Microstructure and Hardness Properties of ZrO2+Y2O3/Al2O3 Layers Coated by Using Plasma Spray Process on Al Bronze Surface
Authors: Özel Serkan , Turhan Hüseyin 
Published: December 2013

Abstract
In this study, ZrO2 + Y2O3/Al2O3 powders were coated on the surface of aluminum bronze (Cu + 5 % Al) by using the atmospheric plasma spraying method. The effect of Al2O3 on microstructure and hardness was examined in four different coatings applied by using 5-10-20 % Al2O3 ratio in ZrO2 + Y2O3 and ZrO2 + Y2O3. For this purpose, microstructure images of the coated layers were taken in optical microscope and SEM, EDX and XRD analyses were performed and their microhardness values were measured. It was observed that a porous structure occurred in the coatings containing ZrO2 + Y2O3/Al2O3. The coatings containing Al2O3 showed higher microhardness values than the one without Al2O3, and depending on the increase of Al2O3 amount, the amount of porosity increased and microhardness value decreased.
Effect of Sn on the Characteristic Solidification Temperatures of AlSi6Cu4 Alloy
Authors: Djurdjevic M. , Muche D. , Stauder B. , Eigenfeld K. 
Published: December 2013

Abstract
The solidification path of AlSi6Cu4 alloy with various content of Sn has been investigated using cooling curve techniques. The content of Sn has been varied from 0 to 500 ppm. The hardness of as cast alloys with different content of Sn has been measured. The results show that Sn in synthetically designed AlSi6Cu4 alloy (very low level of other elements) precipitate isolated. The increased content of Sn decreases significantly the solidus temperature of this alloy, prolonging its solidification temperature interval for approximately 9K. The hardness of this alloy has been reduced for about 20% by presence of Sn up to 500 ppm.
Influence of the Metallic Die Graphite Layer Thickness in the Microstructure of Aluminium Bronze Alloy
Authors: Cenoz Isaac 
Published: December 2013

Abstract
The phases obtained in copper aluminium bronze alloy (Cu-Al10-Fe2) cast into a permanent die were investigated. The parameters examined were the pre-heating temperatures of the die and the graphite coating thickness. The phases α and γ2 were detected as well as the metastable phases β’ and γ’. The intermetallics of the system Fe-Al were obtained in various stoichiometric compositions. The different cooling rates of the casting resulted in two mechanisms of transformation to α grains out of the unstable β phase, one being nucleation and growth producing needle shaped α grains, the other exhibiting a massive transformation to spherical α grains. These two mechanisms determine the changes in the size of the α grains as a result of changes in the cooling rate in its various ranges.
Materials Technology for Advanced Land Based Gas Turbines
Authors: Matijasevic-Lux Biljana , Neidel Andreas 
Published: December 2013

Abstract
Gas turbines have found increasing application in electric power generating plants in addition to the established applications for aircraft and marine propulsion. The success of the gas turbine in these applications has led to demands for units with increased power output but the development of engines designed to meet these demands has presented difficult technological problems.
In modern gas turbines engines, engine firing temperatures still constantly increase in order to improve the thermal efficiency of these machines. These targets are met through the use of advanced designs, materials, and coatings for hot gas path components.
Zementitnachweis zur Unterscheidung von Bainitstufen in modernen, niedriglegierten Mehrphasenstählen
Authors: Miyama Elisabeth , Voit Christina , Pohl Michael 
Published: December 2013

Kurzfassung
Bainitische Gefügeausprägungen kommen bei modernen, niedriglegierten Mehrphasenstählen verstärkt vor. Die Kenntnis der Bainitausprägung in Abhängigkeit der Legierungskonzepte und Herstellrouten ist wichtig, um entsprechende Festigkeitsniveaus gezielt einzustellen. Dabei spielt vor allem die Ausscheidungsmorphologie von Zementit eine entscheidende Rolle, um eine eindeutige Phasenzuordnung treffen zu können. Zur Darstellung und Auswertung der submikroskopischen Zementitausbildung wird bis dato die zeit- und damit kostenaufwändige Durchstrahlungselektronenmikroskopie (TEM) verwendet.
Die vorliegende Arbeit zeigt, dass es durch Optimierung und Anwendung einer geeigneten Präparations- und Abbildungstechnik auch mit hochauflösender Rasterelektronenmikroskopie möglich ist, die Ausscheidungsmorphologie des Zementits in bainitischen Gefügen gut darzustellen und zusätzlich quantitative Kennwerte, wie Teilchenlänge, -anzahl, sowie -verteilung auszuwerten. Die optimierte Präparations- und Abbildungstechnik ermöglicht es künftig, im Vergleich zum TEM umfangreichere, statistisch abgesicherte und somit auch kostengünstiger Untersuchungen zur Zementitausbildung durchzuführen.
Materialographische Untersuchungen an Dentalwerkstoffen
Authors: Behrend Detlef , Warkentin Mareike , Specht Olaf , Schmidt Wolfram , Rosentritt Martin , Ottl Peter 
Published: December 2013

Kurzfassung
Aufgrund der demographischen Entwicklung steigt der Bedarf an geeigneten Werkstoffen und Biomaterialien für die Zahnerhaltung und auch für den Zahnersatz kontinuierlich. Im Fokus stehen hierbei Werkstoffe, die aufgrund ihrer physikochemischen, mechanischen und biologischen Eigenschaften die Qualität und Langlebigkeit in den Bereichen der minimalinvasiven Prophylaxe, Füllungstherapie, zahnärztlichen Prothetik und Implantologie signifikant verbessern. Nur durch die Kombination verschiedener mikroskopischer Untersuchungsverfahren ist es möglich, die Struktur-Eigenschaftskorrelation detailliert zu untersuchen und zu charakterisieren. Somit können die Funktionalitätsparameter der Werkstoffe optimiert werden, um dentale Werkstoffe mit optimierten Eigenschaften zu entwickeln.
Effizienteres Aushärten UV-sensitiver Einbett-Materialien
Authors: Amrhein Frank , Kehrer Martin , Schreck Timo , Bochtler Ulrich , Hellmann Ralf , Kaloudis Michael 
Published: December 2013

Kurzfassung
Im nachfolgenden Artikel wird eine neuartige Vorgehensweise zum Aushärten von UV-sensitivem Einbettmaterial mittels Leuchtdiodentechnologie beschrieben. Durch den Einsatz monochromatischer UV-Strahlung war es möglich, die Aushärtezeiten im Vergleich zur Aushärtung mit konventionellen Quecksilberdampflampen drastisch zu reduzieren. Weiterhin konnte die minimal notwendige Bestrahlungsdosis für die jeweils untersuchte Einbettmasse bestimmt und eine materialspezifische Kenngröße berechnet werden, wodurch die Ermittlung der exakten Aushärtezeit für eine vollständige Aushärtung möglich ist.
Examination of the Mg-Zn Phase Formation in Hot-Dip Galvanized Steel Sheet
Authors: Zywitzki O. , Modes Th. , Scheffel B. , Metzner Ch. 
Published: December 2013

Abstract
Zinc-magnesium layers have been produced by a combination of conventional hot-dip galvanizing and PVD magnesium coating. A subsequent short heat treatment causes the diffusion of magnesium into the zinc layer. The influence of the maximum temperature of the heat treatment on the diffusion of magnesium and on the type and distribution of the formed intermetallic Mg-Zn phases has been examined in detail in a temperature range from 300 to 400°C by means of X-ray phase analyses and metallographic cross sections. With increasing temperature a sequential intermetallic Mg-Zn phase formation has been detected. At 300°C, an initial magnesium rich, intermetallic MgZn2 surface layer is formed, which, at higher temperatures from 335 to 379°C, is progressively transformed into a zinc rich Mg2Zn11 layer by interdiffusion. In this context, the nucleation of the Mg2Zn11 phase takes place on the interface between the MgZn2 and the Zn phase. Above the peritectic temperature of 381°C, the microstructure is composed of a zinc matrix in which precipitated MgZn2 is dispersed.
Detection of Dendrite Coherency Temperature of Aluminum Alloys Using Single Thermocouple Technique
Authors: Djurdjevic M. , Odanovic Z. , Zak H. 
Published: December 2013

Abstract
The dendrite coherency point (DCP) temperature refers to the state of a solidifying alloy at which a coherent dendrite network is established during the formation of grains. There are three main approaches for detection of DCP: (i) the thermal analysis method, (ii) mechanical (or rheological) technique and (iii) physical method based on the thermal diffusivity measurement technique.
There are two basic variants of the thermal analysis method. In the late 1980's Bäckerud developed a method that utilizes two thermocouples. The DCP is determined by identifying the point of minimum temperature difference at the δT curve (TW–TC). Recently, has been revealed that utilization of the first derivative curve (dT/dt) plotted versus temperature also allows for analysis of the α-Al dendrite nucleation and growth characteristics and consequently determination of the DCT. This paper will illustrate that the dendrite coherency temperature could be identified by the 1st derivative curve (the one-thermocouple method) with the same accuracy as well as by using two thermocouples technique.
Liquation Cracks in Hot Upset Low Alloy Steel Screw Heads
Authors: Neidel A. , Riesenbeck S. 
Published: December 2013

Abstract
A thermally upset screw head had numerous cracks at the intersection screw head / screw shaft. The screw consisted of steel that usually does not tend to hot crack. The screw failed when tightening it by applying a torque lower than the nominal torque. The screw head was simply sheared off.
A hot crack has clearly been identified as damage-causing mechanism of the material, or, more precisely, liquation cracks. Other damage hypotheses such as liquid metal induced stress corrosion cracking have reliably been excluded in the course of examinations.
The material used was 1.7711, 40CrMoV4–6, a material especially used for creep resistant fasteners such as screws and nuts for operating temperatures up to 540°C. This material belongs to the group of low alloy chromium molybdenum vanadium steels. It is typically used in the tempered condition. In Europe, it corresponds to standard EN 10269. In the USA, this steel is known as ASTM A193 GR B16.
Sample Preparation by Metallography and Focused Ion Beam for Nanomechanical Testing
Authors: Moser G. , Felber H. , Rashkova B. , Imrich P.J. , Kirchlechner C. , Grosinger W. , Motz C. , Dehm G. , Kiener D. 
Published: December 2013

Abstract
Mechanical size effects in micron and submicron scale sample testing are of immense interest in materials science. In this work, we report on a combination of structured chemical etching and focused ion beam fabrication to allow site specific and time efficient fabrication of miniaturized specimens for mechanical testing. Further, we demonstrate the applicability of these samples for quantitative in situ experiments in the scanning and transmission electron microscopes.
Assessment of Some Methods for Grain Size Measurement
Authors: Markoli B. , Naglič I. , Prosenc M. , Kuhar V. 
Published: December 2013

Abstract
Due to the fact that grain size measurement in metallic materials is of great importance, five well known and established grain size measurement methods were compared for accuracy and time consumption, i. e.: comparison method, intercept method, planimetric method (by Jeffries), planimetric delineation method performed in semiautomatic manner and automatic method (commercial software by ZEISS). For that purpose standard low-carbon ferritic steel (W. NR. 1.0360), austenitic steel (W. NR. 1.4404) with two different grain sizes (denoted as A and B) and nodularized grey cast iron (EN-JS 1082) were chosen.
It was discerned that the comparison method represents the fastest solution for the grain size measurement but it is limited in precision and applicability in two phase materials. The automatic (commercially available software) method was proved to be unreliable, while the intercept method or one of the planimetric methods is the most reasonable choice when higher accuracy is required.
Corrosion Damage to a Dropped Handlebar Made of AA7075
Authors: Schneider M. , Langklotz U. , Sempf K. 
Published: December 2013

Abstract
Damage by corrosion was discovered on a dropped handlebar made of AA7075 during an inspection at a workshop. The possible causes are presented and the corrosion types encountered are interpreted. Stress corrosion or corrosion fatigue under the effect of chloride can be concluded from the damage pattern and reconstructed conditions of use. The heterogeneous microstructure containing a large number of intermetallic precipitates accelerates the start of corrosion because microgalvanic elements are formed. Although aluminium alloys, when in an urban environment, do not exhibit a pronounced tendency to corrosion the conditions of corrosion can locally change in use to such an extent that corrosion damage will occur. In the present case, a remedy can primarily consist in inspections at well-adapted intervals and the exchange of the handlebar tape in good time.
Oxidation and Mechanical Behaviors of Two Phase (Mo + T2(Mo5SiB2)) and Three Phase (Mo + T2(Mo5SiB2) + Mo3Si) Alloys at 1 073 K and 1 373 K
Authors: Park J. S. , Kim J. M. , Kim H. Y. 
Published: December 2013

Abstract
The oxidation behaviors of Mo rich alloys have been investigated in the Mo-Si-B ternary system. Seven selected alloy systems composed of two phase alloys (Mo (solid solution) + T2 (Mo5SiB2) and three phase alloys (Mo (solid solution) + T2 (Mo5SiB2) + Mo3Si) have been fabricated by arc melting elemental components. Mechanical behaviors of the selected alloy systems have been investigated in order to identify the effect of composition on the ternary system. Also, oxidation tests have been performed in order to identify the oxidation behaviors at 1 073 and 1 373 K. When the alloy compositions move towards the Mo side, the oxidation reactions were accelerated for the two phase alloys due to the presence of Mo (s. s.), while the tendency of oxidation was not fast for the three phase alloys. The oxidation behaviors at above and below 1 273 K have been discussed in terms of microstructural observations during oxidation tests.
Application of Complementary Techniques for Advanced Characterization of White Etching Cracks
Authors: West O. H. E. , Diederichs A. M. , Alimadadi H. , Dahl K. V. , Somers M. A. J. 
Published: December 2013

Abstract
White etching crack (WEC) networks were characterized in heavy loaded bearings for wind turbines. Both conventional techniques as reflected light microscopy and (scanning and transmission) electron microscopy as well as electron backscatter diffraction and ion channelling contrast imaging were applied. The complementary use of the techniques in unravelling the complicated failure mechanisms is explored in the present work.
Study of the Impact of Multiple Weld Repairs and Associated Stress-Relief Annealing on Mechanical Properties at Elevated Temperatures of Large Components Made of the Low-Alloy Steel 16Mo3
Authors: Giller M. , Lehmann K. 
Published: December 2013

AbstractThis paper is related to 16Mo3, a low-alloy steel typical in the manufacture of large welded steel casings of heavy-duty gas turbine engines. The usual practice in manufacturing is to stress relieve these housings after fabrication welding. If, however, weld imperfections are detected by non-destructive testing, weld repairs are performed, followed by additional stress-relief heat treatments. The methods applied were used to detect possible embrittlement by secondary carbide precipitation and to finally draw conclusions on material changes. The critical area of a weld is the heat affected zone. In this area a worsening of the stress condition in connection with a change in carbide precipitation and thus a decrease in creep rupture strength occurs. A concrete alloy composition and heat treatment adapted to the precipitation behavior are important, because they determine the type, amount and distribution of the resulting carbides [1, 2].
Polymer/Layered Silicate Nano-composites
Authors: Okamoto M. 
Published: December 2013

Abstract
Polymer/layered filler nano-composites (PLFNCs) offer remarkably improved mechanical properties with low inorganic filler loading. Major developments in this field have been carried out over the last one and half decades. However, we are far from the goal of understanding the mechanisms of the enhancement effects in nanocomposites. Continued progress in nanoscale control, as well as an improved understanding of the physicochemical phenomena at the nanometer scale, has contributed to the rapid development of novel PLFNCs. We describe nano-structure development and processing operations in PLFNCs.
The Effect of Post-extrusion Conditions in Ribbon Extrusion of Polymer Blends
Authors: Ramirez-Arreola D. , Padilla-López H. , González-Núñez R. , Rodrigue D. 
Published: December 2013

Abstract
Blends of high density polyethylene and polystyrene were produced via ribbon extrusion to study the effect of post-extrusion conditions on the ribbon final dimensions and morphology. An experimental setup was designed to measure the stretching force as a function of draw ratio and water contact distance for blends of 3, 6 and 9% PS in HDPE. Numerical simulations of the non-isothermal process using Matlab were in good agreement with the experimental data only when both viscous and elastic effects are included. The results show that both draw ratio and water contact distance have a definite influence on the final dimensions of the ribbon and the stretching force. It was found that deformation of the dispersed phase increases with draw ratio, but decreases with water contact distance.