bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitrocarburising in ammonia-hydrocarbon gas mixtures
Authors: Pedersen H. , Christiansen T. L. , Somers M. A. J. 
Published: December 2013

Abstract

The present work investigates the possibility of nitrocarburising in ammonia-acetylene-hydrogen and ammonia-propene-hydrogen gas mixtures, where unsaturated hydrocarbon gas is the carbon source during nitrocarburising. Consequently, nitrocarburising is carried out in a reducing atmosphere and straightforward control of the carburising and nitriding potentials is in principle possible. The nitrocarburising response of unalloyed (ARMCO) Fe was investigated in a thermobalance during controlled nitrocarburising at 580°C. The “cases” obtained on nitrocarburised iron were characterized by reflected light microscopy and X-ray diffraction analysis. It is shown that the use of unsaturated hydrocarbon gas in nitrocarburising processes is a viable alternative to traditional nitrocarburising methods.
Sensorkontrolliertes Gasoxinitrieren von Warmarbeitsstählen mit Ammoniak-Wasser-Gemischen
Authors: Lippmann N. , Kizil Ü. , Öklü B. 
Published: December 2013

Kurzfassung

Düsenkörper in höchstbelasteten Dieseleinspritzsystemen werden stetig steigenden Applikationstemperaturen ausgesetzt, denen die bisher verwendeten einsatzgehärteten Bauteile nicht mehr gerecht wurden. Um diesen Beanspruchungen zu begegnen, wurden Düsenkörper aus nitriertem Warmarbeitsstahl entwickelt, die bei Temperaturen bis zu 450°C belastet werden können.
Wegen der starken Passivierungsneigung des Warmarbeitsstahls und wegen des Vorprozesses mit elektrochemischem Abtragen musste ein Gasoxinitrierprozess angewendet werden. Die Kontrolle des Oxidationspotenzials im verwendeten Ammoniak-Wassergemisch erfolgt dabei durch eine Sauerstoffsonde. Mittels eines Wasserstoffsensors kann das Nitrierpotenzial geregelt werden, sodass auch eingeschränkte Verbindungsschichtdicken realisiert werden können.
Controlled nitriding and nitrocarburizing – state of the art
Authors: Winter K.-M. , Hoja S. , Klümper-Westkamp H. 
Published: December 2013

Abstract

The process of gaseous nitriding is considered to be fully controllable by temperature and the nitriding potential. Most of the commercially used control systems are based on the Lehrer Diagram showing the relation between nitrogen-iron phases, temperature and the partial pressure ratio of ammonia and hydrogen. This is also reflected in the measuring equipment used to determine the nitriding potential. Lehrer's phase diagram was created out of the reactions between set gas mixtures of ammonia and hydrogen and pure iron powder. In industrial nitriding cycles, dealing with real materials and real parts, the results often do not match the expectations. This paper will try to explain the parameters that have to be taken into account and how to measure, set and control the nitriding and carburizing potentials by giving an overview of the available equipment.
Bestimmung der Warmhärte von metallischen und keramischen Hochtemperaturwerkstoffen*
Authors: Klemm H. , Nake K. , Bales A. 
Published: December 2013

Kurzfassung

Eine neue Prüfanlage zum Messen der Härte bei hohen Temperaturen wird vorgestellt. Sie ermöglicht es, die Härte (Vickers- und Knoophärte) im Temperaturbereich von 300–1500 °C im Vakuum zu bestimmen. Die Härtetests werden mit Diamantprüfkörpern und Prüfkräften im Bereich von 9,81 N bis 294,30 N auf einer polierten Probenoberfläche bei der entsprechenden Testtemperatur durchgeführt. Die Auswertung der Härteeindrücke erfolgt nach dem Abkühlen der Proben mit einem Lichtmikroskop.
Mithilfe der Temperaturabhängigkeit der Härte verschiedener metallischer und keramischer Materialien werden Potenzial und Grenzen dieser Prüfmethode dargestellt. Es wird gezeigt, dass mit der Bestimmung der Warmhärte ein sehr nützliches Instrument für die Entwicklung metallischer und keramischer Hochtemperaturmaterialien zur Verfügung steht.
Optimised press-hardening process using spray cooling – process integrated heat treatment of 22MnB5 sheet metal
Authors: Diekamp M. , Hübner S. , Nürnberger F. , Schaper M. , Behrens B.-A. , Bach Fr.-W. 
Published: December 2013

Abstract

Press-hardening is a comparatively time consuming forming process since both forming as well as quenching is performed in the die tool. In order to accelerate this process, an alternative cooling strategy is considered which is based on spray cooling outside the die tool. The object of our investigation is 22MnB5 material. Quenching tests show that sufficient cooling rates greater than 50 K/s can be obtained by means of water-air spray cooling using two-component nozzles. The strength values and fracture strains realised here correspond to the mechanical properties attainable during press-hardening. Furthermore, a plant design is presented which is suitable for cooling vehicle body parts such as tunnels in order to reduce the turnaround time by means of prematurely removing the components from the die-forming tool and subsequently cooling in a spray field.
Modeling the relationship between hardness and spray cooling parameters for pinion shafts using a neuro-fuzzy model strategy
Authors: Yu Zhuo , Kuznietsov Kostiantyn , Mozgova Iryna , Böhm Vera , Gretzki Thorsten , Nürnberger Florian , Schaper Mirko , Reimche habil-Wilfried 
Published: December 2013

Abstract

The production of pinion shafts having a predefined hardness distribution faces the challenge of analytically describing the relationship between pinion shafts hardness and spray cooling parameters. The present work attempts to establish this type of mutual relationship based on radial basis function (RBF) neural networks regarding precision forged and spray-cooled pinion shafts. A method for increasing the ability of generalising RBF-Networks via fuzzy inputs is discussed. The results indicate that the relationship between the pinion shaft's hardness and spray cooling has been obtained by using the proposed network. The optimum process parameters can be selected to achieve the desired hardness profile on the basis of the predicted results.
Influence of different deep cryogenic treatment routes on the properties of high speed steel
Authors: Pellizzari M. , Caliskanoglu D. , Fernández A. , Barbero J. I. , Pena B , Uemit T. , Sanz R. Pizarro , Eguizabal R. Elvira , Alava L. A. 
Published: December 2013

Abstract

An intensive research work was carried out in the frame of a RFCS (Research Found for Coal and Steel) project, to investigate the influence of different deep cryogenic treatments (DCT) on hardness, strength, toughness and wear resistance of AISI M2. Short and a long classical DCT, providing the soaking at temperature close to the boiling point of liquid nitrogen (−196 °C) for 6 h and 20 h, respectively, were carried out prior to and after tempering. Furthermore, a third short DC route, providing temperature cycling between RT and low temperature was also considered. Care was taken to avoid stabilization of retained austenite or self tempering due to wait at room temperature prior to DCT and/or tempering. All treatments were calibrated to get 840 HV 10, in order to compare the properties of steel with the same reference hardness. DCT does not allow the complete transformation of retained austenite in the investigated high speed steel, due to the stabilizing effect of alloying elements. Tempering is necessary to completely transform this phase and to allow proper secondary hardening. If carried out after quenching, DCT shifts the secondary hardness peak to lower temperature, evidencing the need to adjust the tempering parameters to avoid overtempering. The microstructure didn't show any significant influence of DCT in terms of carbides distribution, due to the conditioning of martensite at low temperature. The same can be also concluded for the other properties (toughness, tensile strength and wear resistance), which are practically the same for samples having the same hardness.
Einfluss der Oberflächenfertigung und des Nitrierens auf den Eigenspannungszustand des warmfesten Stahls X38CrMoV5-3
Authors: Hoja S. , Klümper-Westkamp H. , Epp J. , Hoffmann F. , Zoch H.-W. 
Published: December 2013

Kurzfassung
Um den hohen Beanspruchungen bei der Warmmassivumformung zu begegnen, werden die Oberflächen und Randbereiche der eingesetzten Werkzeuge nitriert. Durch das Nitrieren entstehen hohe Druckeigenspannungen in Oberflächennähe. Aber auch die Fertigungsbedingungen führen zu Eigenspannungen im Randbereich, die bei dem warmfesten Stahl X38CrMoV5-3 während des Nitrierens nur teilweise abgebaut werden können. In der vorliegenden Arbeit wurden Eigenspannungen an unterschiedlich gefertigten Proben gemessen, um die sich ergebenen Spannungen aus der Fertigung und der Nitrierbehandlung zu ermitteln. Die fertigungsbedingten Druck- und Zugeigenspannungen werden beim Nitrieren des Warmarbeitsstahls nicht abgebaut. Nach dem Nitrieren wurden Druckeigenspannungen von bis zu −1000 MPa gemessen.
Deep rolling of austenitic steel AISI 304 at different temperatures – near surface microstructures and fatigue
Authors: Nikitin I. , Scholtes B. 
Published: December 2013

AbstractIn metastable austenitic stainless steelsthe formation of high dislocation densities, compressive residual stress states, strain-induced martensite and nanocrystalline regions are the most important consequences of mechanical surface treatments leading to retarded fatigue crack initiation as well as propagation. These properties can be altered in a characteristic way applying different deep rolling temperatures. The main objective of this paper is to clarify the role of the different near surface microstructures introduced by deep rolling operations on the fatigue behaviour of steel AISI 304 especially in the low cycle fatigue region. For this purpose special experimental techniques were applied allowing deep rolling operations in the temperature range between −192 °C and +700 °C. Results clearly show that the amount of strain induced martensite by deep rolling in near surface layers is less important than the stability of the microstructures under fatigue loading.
Improvement of fracture toughness and tensile ductility of massive rings made of 18 % nickel maraging steel
Authors: Rao M. Nageswara , Chatterjee M. , Sivasubramanian K. 
Published: December 2013

Abstract

Massive rings of 18% nickel maraging steel produced using the ring rolling process do not consistently attain high fracture toughness (KIc) and tensile ductility values. Due to large section sizes involved, it becomes difficult to suppress precipitation of carbonitride particles and prevent thermal embrittlement. The conventional heat treatment of solutioning at 820 °C followed by aging at 480 °C is not effective in undoing this embrittlement. Different multi-stage solution treatments were designed and tried out to improve the mechanical properties. A two-stage (950 °C + 820 °C)/three-stage (950 °C + 950 °C + 820 °C) solution treatment, depending on the section size, proved to be effective. This treatment leads to recrystallisation of the as-hot-worked microstructure and a fine grain size; it is believed that a delinking of grain boundaries and carbonitrides occurs simultaneously. The observed improvement of fracture toughness and tensile ductility can thus be explained.
Numerische Berechnung einer integrierten Wärmebehandlung für präzisionsgeschmiedete Bauteile
Authors: Behrens B.-A. , Bach Fr.-W. , Bouguecha A. , Nürnberger F. , Schaper M. , Yu Z. , Klassen A. 
Published: December 2013

Abstract

Precision forging is a production process used for manufacturing of near-net shaped, highly loaded components with low proportion of forging degrees and reduced necessity of post processing. In comparison to the conventional forming and the machining production processes, an important improvement in material savings and a significant shortening of the process chain can be obtained. The near-net shape forging allows an integrated heat-treatment from the hot-forming heat. In this paper, a numerical calculation of the forging process and a heat-treatment process following forging are shown at the example of the pinion shaft. A challenge lies in the coupling of the simulation model for the forging process and the model used to calculate the temperature and microstructure development during quenching and tempering process. This coupling in addition to the illustration of the entire process, enable optimization of spray cooling parameters which leads to the diesired hardness profile.
The simultaneous efect of extrusion and T6 treatment on the mechanical properties of Al-15wt.%Mg2Si composite
Authors: Soltani N. , Bahrami A. , Moghimi F. M. , Pech-Canul M. I. , Hajaghasi A. 
Published: December 2013

Abstract

This article investigates the simultaneous efect of extrusion ratio and T6 heat treatment on microstructure and mechanical properties of in-situ Al-15wt.%Mg2Si composite. his composite has already been introduced as a new class of light materials but the brittle structure of the primary Mg2Si which is formed during solidiication limits its application. As-cast composite was directly extruded as rod by using three diferent dies. Ater T6 heat treatment on extruded samples, microstructure was studied by optical and scanning electron microscopy. Results demonstrated that extruded and heat treated composite possesses considerably higher strength and enhanced ductility in comparison with the as-cast samples. It was also found that heat treatment and extrusion processes change the primary Mg2Si morphology considerably and its size increases as extrusion ratio decreased. Fracture surface examinations revealed a transition from brittle fracture mode in as-cast composite to ductile fracture in heat treated and extruded specimens. his can be attributed to the changes in size and morphology of Mg2Si intermetallics and porosity content.
Verzugsentstehung bei Scheiben aus 20MnCr5 – Einfluss von Umformung und Gefügestruktur
Authors: Rentsch R. 
Published: December 2013

Kurzfassung

Für die Zahnradfertigung werden zunächst aus warmgewalzten Stangenabschnitten Scheiben geschmiedet. Die Scheiben aus 20MnCr5 (AISI 5120) werden anschließend auf Maß gedreht und auf einer Wälzfräsmaschine verzahnt. Nach dem Einsatzhärten wird mit dem Verzahnungsschleifen die genaue Geometrie der Zähne hergestellt. Enge Toleranzen von wenigen Mikrometern sind für die Erfüllung der Verzahnungsqualitäten von Hochleistungsgetrieben sowie für stabile Fertigungsprozesse einzuhalten.
Experimentelle Analysen zeigen, dass der Stofffluss in scheibenförmigen Zahnradrohlingen signifikant variieren kann. Zusätzlich zeigten detaillierte WDX-Messungen eine Makroseigerung am Querschnitt der zylindrischen Stangenabschnitte, aus denen die analysierten Scheiben hergestellt wurden. Beides ist für die Zahnradherstellung von Bedeutung, da eine Korrelation zwischen dem Scheibenverzug nach dem Einsatzhärten der Scheiben und dem jeweils im Zahnrad ausgebildeten Stofffluss für diesen Stahl gefunden wurde. Neben den experimentellen Analysen wurden FE-Analysen zum Einfluss von Prozessparametern und Prozessstörungen auf den Scheibenverzug durchgeführt. Als ein wesentlicher Faktor für den Scheibenverzug wurde ein Temperaturgradient über der Höhe der Zylinderabschnitte identifiziert, der über den Stofffluss auf das Verzugsverhalten der Scheiben nach dem Einsatzhärten zum Tragen kommt.
Influence of short-cycle heat treatment conditions on the hardness-toughness-relationship of the steels 51CrV4, 74NiCr2 mod. and 100Cr6∗
Authors: Steineder K. , Schneider R. 
Published: December 2013

Abstract

The paper covers the effect of various heat treatment conditions, with a focus on short-cycle heat treatment, on the mechanical properties (hardness and toughness) of the steels 51CrV4, 74NiCr2 mod. and 100Cr6. To determine this property-relationship, micro-impact samples were heat treated under various conditions in a dilatometer. Afterwards the samples were tested regarding their impact toughness and Vickers hardness. Furthermore, additional investigations of the microstructure (optical), the retained austenite content (XRD) and the fracture behaviour (SEM) were performed. Selected dilatometric measurements on the transformation behaviour after short austenizing durations completed the investigation program. Tempering at temperatures in the range of 200 °C always provided a favourable property-relationship. While short-cycle heat treatment conditions only lead to a slightly reduced toughness at similar hardness, overheating resulted in a more significant loss in toughness with different severity for the three steel grades. Microstructural investigations provide additional information to explain this behaviour.
Experimental characterization and simulation of a wire drawing process and related distortion potentials∗
Authors: da Silva Rocha A. , Nunes R. M. , de Souza T. F. , Soares C. A. T. , Haenisch S. , Tekkaya A. E. , Hirsch T. 
Published: December 2013

Abstract
In this investigation a DoE (Design of Experiments) analysis of distortion for a typical manufacturing process of pre-straightened, cold drawn and induction hardened AISI 1045 cylindrical steel bars was carried out. A careful characterization of the material, including residual stresses and geometrical changes was done for the different manufacturing steps. The variables included the drawing process itself with two different drawing angles, a stress relief treatment which was applied to one part of the samples and finally an induction heat treatment with two different case depths applied to identify effects and correlations on distortion. Simulation of the drawing process was also used as tool to clarify possibilities and limits of this kind of analysis, depending on the available input data. Different influences on the distortion of the induction hardened samples were found and discussed, as for example the marked dependence of the distortion on drawing angle.
Application of Column Flotation for Egyptian Graphite
Authors: Abd EL-Rahiem Fatma H. 
Published: December 2013

Abstract
This paper focuses on the graphite flotation from Bent Um Qureia ore at Eastern desert of Egypt. Minerals in ore were evaluated by XRD. The sample was crushed in jaw crushing. The sample was ground minus 74 μm and the product was then sieved +45 and −45 μm. The conventional and column flotation were used to float the graphite. In two flotation techniques, kerosene was used as a collector. Factor affecting the graphite grade was investigated. The rougher concentrate was cleaned in both conventional cell and column to compare the performance. The effects of different variables were evaluated in both cases and the conditioned were optimized to achieve better grade and recovery. The results indicate that column can give superior performance compared to conventional cell by either reducing the number of stages of operation or by improving grade and recovery.
Gypsum Scale Formation on Heat Exchanger Surfaces: The Influence of Natural and Synthetic Polyelectrolytes
Authors: Amjad Z. 
Published: December 2013

Abstract
The precipitation and deposition of calcium sulfate dihydrate (gypsum) on brass heat exchanger surfaces from aqueous solutions has been studied using a highly reproducible technique. It has been found that gypsum scale formation takes place directly on the surface of the heat exchanger without any bulk or spontaneous precipitation in the reaction cell. A variety of natural and synthetic polyelctrolytes such as fulvic acid, tannic acid, poly-(acrylic acid) and acrylic acid — based copolymers containing sulfonic group(s) have been examined for their effects on the rate of scale formation. The results indicate that the amount of gypsum scale formed on heat exchanger surface is strongly affected by polyelectrolyte architecture and concentration of polyelectrolyte. Scanning electron microscopic investigations of gypsum crystals grown in the presence of polyelectrolytes (natural and synthetic) show that structures of these crystals are highly modified.
Dynamic Interfacial Behavior of Decyl Methylnaphthalene Sulfonate Surfactants for Enhanced Oil Recovery
Authors: Zhao Zhongkui , Ba Yan , Li Zonghsi , Qiao Weihong , Cheng Lübai 
Published: December 2013

Abstract
The high purity decyl methylnaphthalene sulfonate (DMNS) was synthesized, the purity was determined by HPLC and the structure was confirmed by IR, UV and ESI-MS. Dynamic interfacial tensions (DIT) between DMNS flooding systems and crude oil were measured and the effects of sodium carbonate concentration, surfactant concentration and sodium chloride concentration on the DIT behaviors were investigated. It's found that the surfactant concentration, alkali concentration and the salinity have obvious influences on DIT behaviors. DMNS possessed outstanding capacity and efficiency of lowering the DIT between oil and water. The minimum dynamic interfacial tension could reach 6.35×10−6 mNm−1 at a lowconcentration for added surfactant. DMNS might be used in Enhanced Oil Recovery with lowcosts and high efficiency.
Mesoscale Computer Simulations on the Phase Behavior of the Non-Ionic Surfactant C12E5
Authors: Schulz S. G. , Frieske U. , Kuhn H. , Schmid G. , Müller F. , Mund C. , Venzmer J. 
Published: December 2013

Abstract
Dissipative Particle Dynamics is a mesoscopic simulation method which allows to predict the self-assembly of amphiphilic polymers and surfactants. It was possible to reproduce the phase behavior of the non-ionic surfactant C12E5 in water. The three different phases L1, La and L2 could be characterized with Dissipative Particle Dynamics.
Nonionic Tenside Ligands and its Application in Biphasic Catalysis
Authors: Zilin Jin , Cuilan Feng , Yanhua Wang 
Published: December 2013

AbstractThis review article mainly surveys our research results of biphasic catalysis with nonionic tenside ligands. Emphasis is given to the synthesis and property of cloud point of the nonionic tenside ligands, the general principles of thermoregulated phase-transfer catalysis (TRPTC) and thermoregulated phase-separable catalysis (TPSC). It also explores the applications of TRPTC and TPSC in the hydroformylation of higher olefins and CO selective reduction of nitroarenes. The introduction of TRPTC to biphasic systemis free from the shortcomings of classical aqueous/organic two-phase catalysis, in which the application scope is restrained by the water solubility of the organic substrate. The biphasic catalysis with nonionic tenside ligands was characterized by homogeneous catalysis coupled with convenient biphasic separation.
Synthesis of δ Layered Sodium Disilicate with High Framework Stability
Authors: Dong Jinxiang , Xu Hong , Zhang Gaoyong , Li Jinping , Lian Genwang 
Published: December 2013

AbstractIn this paper, δ layered sodium disilicate with high framework stability has been synthesized by adding the salts of divalent and trivalent elements. In these salts AlCl3had the best effect for leaving the phase transformation of δ-Na2Si2O5. XRD, SEM, Ca2+ion binding capacity and clean experiment were used for measuring their properties. The data proved that Al-δ-Na2Si2O5had good framework stability. δ phase was still major phase after Al-δ-Na2Si2O5was treated in hot water (80°C) for 60 minutes. And Ca2+ion binding capacity may keep at 305 mg CaCO3/g through the treatment. The cleaning experiments showed that Al-δ-Na2Si2O5had good washing ability.