bluuebunny/crossref_metadata_2025_split huggingface dataset:
Resistivity of electrical sheets in high temperatures
Authors: Soiński Marian 
Published: December 2016

The paper presents changes in electric resistivity ϱ, dependent on the temperature T for oriented and non‐oriented electrical sheets. The analysis of temperature changes on the temperature coefficient of resistivity α was performed for different sheet grades. Various methods were used to mathematically describe empirical data obtained. The influence of non‐metallic inclusions and crystallographic dislocations on the resistivity value was detected. For the sheets under examination, the values of residual resistivities ϱr (at 4.2 K) and ideal resistivities (at 400 K) were provided.It was suggested that apart from the value of the temperature coefficient of resistivity α, the value of residual resistivity ϱ, be used to classify sheets of different chemical constitution. This seems to be of particular significance for better material characteristics on view of newly designed electric machines adapted to operate in ever higher temperatures.
Mathematische Beschreibung der MgO‐Sättigung in komplexen Stahlwerksschlacken beim Gleichgewicht mit flüssigem Eisen
Authors: Schürmann Eberhard , Kolm Ingo 
Published: December 2016

Zur Verminderung des Feuerfestverschleißes wird bei der Stahlerzeugung der MgO‐Träger Dolomitkalk als Schlackenbildner eingesetzt. Dies erfordert genaue Kenntnisse der in Abhängigkeit von der Schlackenzusammensetzung und der Temperatur löslichen MgO‐Gehalte, um metallurgisch wirksame, gut flüssige Schlacken zu gewährleisten.Die MgO‐Sättigungsgehalte in Stahlwerksschlacken wurden bei niedrigen, durch das Gleichgewicht mit flüssigem Eisen festgelegten Sauerstoffpartialdrücken experimentell bereits durch eine große Anzahl von Sättigungsschmelzen untersucht, bedurften jedoch einer einheitlichen und auch komplexe Schlacken umfassenden Beschreibung. Alternativ zu schwer lesbaren graphischen Darstellungen wird daher eine numerische Beschreibungsform entwickelt, welche zunächst die MgO‐Gehalte auf der Magnesiowüstit‐Sättigungsfläche im reinen Vierstoffsystem MgO—FeOn—CaO—SiO2 bei 1600°C mit Hilfe eines Gleichungssystems in Abhängigkeit von der Schlackenzusammensetzung erfaßt.Die Gültigkeit der Beziehungen wird sodann auf Mehrstoffsysteme mit mehr als vier Komponenten erweitert, indem Gehalte an MnO, P2O5 und Al2O3 entsprechend ihrer spezifischen Wirkung auf die MgO‐Löslichkeit entweder als verdünnend eliminiert (MnO) oder in äquivalente SiO2‐Gehalte umgewertet werden (P2O5, Al2O3). Auf diese Weise wird das reale, komplexe Mehrstoff‐Schlackensystem in ein bezüglich der MgO‐Sättigungsgehalte äquivalentes Quasi‐Vierstoffsystem MgO*—FeOn*—CaO*—SiO2* überführt. Der Temperatureinfluß kann durch einen auf 1600°C bezogenen Korrekturfaktor berücksichtigt werden.Die vorgestellten Gleichungen ermöglichen es, die in technischen Schlacken löslichen MgO‐Gehalte in einem weiten Konzentrations‐ und Temperaturbereich zu berechnen.
On the reaction mechanism of the carburization and decarburization of α‐iron in CH4/H2‐mixtures
Authors: Sobe Gerhard , Polei Veronika 
Published: December 2016

The surface reaction of the carburization and decarburization of α‐iron in CH4/H2‐mixtures has been investigated by a method using the radioactive isotope 14C. Experimentally two different kinetic equations have been confirmed and discussed in detail:

urn:x-wiley:01774832:srin00846:equation:srin00846-math-0001
In accordance to 1) the kinetic equation (1) is explained by a slow reaction: .For the kinetic equation (2) the adsorption, respectively the desorption of CH4, is considered to be the most slow partial step. The correlation of the carburization with the adsorption is supported by the relations:

urn:x-wiley:01774832:srin00846:equation:srin00846-math-0003
Thus can be regarded as Ea, the activation energy of the adsorption. Its value was determined at 109 kJ/mol being equivalent to 1.1 eV, which is characteristic for a chemisorption.Further it was established, that the rate of the decarburization according to equation (2) increases with decreasing temperature, i.e. the (apparent) activation energy proved to be negative. This is explained by the fact that before its rate‐controlling desorption the CH4‐molecule first of all must be formed step‐by‐step and by the assumption that for thermodynamical reasons the surface concentration of CH4 increases very much with decreasing temperature.The range of validity of the kinetic equations (1) and (2) can be limited to each other as follows:
– The kinetic law (1) is established especially at higher H2‐pressures and at surfaces with low, but effective impurities. The impurities simultaneously result in a high decline of the reaction rate.
– The kinetic law (2) is valid especially at lower H2‐pressures.
Effect of carbon content in CrMoV hot working tool steel
Authors: Berns Hans , Wendl Franz 
Published: December 2016

The aim of this work was to find out whether a reduction of carbon content would reduce the amount of segregated eutectic carbides and improve ductility and toughness. Quenched and temperted specimens of steel X 40 CrMoV 5 1 (∼AISI H 13) were tested at carbon contents of 0.42 and 0.27%. Tensile and short time creep tests were carried out at elevated temperatures. Toughness was derived from unnotched, notched and precracked specimens over a temperature range. Stable fatigue crack growth was measured in CT specimens at room temperature and in thermal fatigue specimens.As expected, ductility and toughness are raised by reducing the carbon content. At the same time a favourable improvement of hot strength and creep resistance appears, causing a lower thermal fatigue crack velocity. These beneficial effects are due to the higher alloy content in solution after hardening.It is proposed to test a steel X 28 CrMoV 5 1 for intricate tools in practical application and learn more about its wear behaviour.
Properties of through hardening bearing steels produced by BOF blowing metallurgy and by electric arc furnace with ladle metallurgy
Authors: Baum Rudolf , Böhnke Kurt , Boeckers Tilman , Klemp Harald 
Published: December 2016

Melting in EAF and BOF‐TBM and different methods of aluminium deoxidation in the subsequent ladle treatment result in a similar degree of cleanness. With respect to micro‐inclusions the air melted ingot and continuous cast steels achieve nearly the same level as remelted steels. Considering macro‐inclusions there still remains a decisive difference: remelted steel is sure to be free from macro‐inclusions, whereas some occasionally occur in air melted steel.The random test and metallographic evaluation systems do not allow uniform classification of the various steel groups. None of the applied methods can determine definite inclusion contents. The number and sizes of the evaluated types of inclusions only can define the statistical probability of their occurrence in a larger lot of heats. Up to now they cannot be related to the fatigue behaviour of the steels. Therefore, further investigation is necessary to reveal the effect of critical sizes and chemistry of the various inclusions on the fatigue behaviour. First tests reveal that the machinability seems to be governed by the carbide grain sizes more than by the sulphur contents in the investigated range of 0.003‐0.015%. The comparison of test results in terms of cleanness and segregation shows that continuous casting should allow the same application as ingot casting.
Ausscheidungsverhalten von nichtrostenden ferritisch‐austenitischen Stählen mit höheren Molybdän‐Gehalten
Authors: Tacke Gerhard , Köhler Heinz Jürgen 
Published: December 2016

Ferritisch‐austenitische Stähle mit Cr‐Gehalten von 20 bis 28%, Nickel‐Gehalten von ca. 5% und Molybdän‐Gehalten zwischen 1,5 und 6% wurden auf ihr Ausscheidungsverhalten unter Berücksichtigung von Wärmebehandlungsquerschnitten bis 200 mm □ untersucht. Mit steigendem Molybdän‐Gehalt nimmt die Ausscheidungsmenge zu. Die in den C‐armen N‐legierten Versuchsstählen dabei auftretenden Phasen sind– kubisches Nitrid des Typs CrN mit 40–80% Cr, bis zu 45% V+Nb und 20% Mo bezogen auf den metallischen Anteil (100%); die Phase wurde im Ferrit und auf Korn‐ und Phasengrenzen beobachtet,– hexagonales (CrMo)Nxmit ca. 80% Cr und 8% Mo, welches nur auf Korn‐ und Phasengrenzen vorliegt,– tetragonale Z‐Phase (CrMo)2Nb2N2mit ca. 35% Cr, 45% Nb, 20% (V/Fe/Mo), die im Austenit fein und im Ferrit grob ausgeschieden vorliegt,und eine kohärente MoFe‐Phase im Austenit einiger Stähle.Im Gegensatz zu den IK‐kritischen Carbiden des Typs Cr23C6in den austenitischen und ferritischen Stählen binden die o.a. Nitridphasen vergleichsweise weniger Cr bzw. Mo ab, nicht zuletzt durch Einbau von V und Nb anstelle des Cr. Mit steigendem Wärmebehandlungsquerschnitt nimmt die Menge an Ausscheidungen erwartungsgemäß zu. In 0,2 μm Abstand von Nitriden wurden in Stählen mit Matrix‐Gehalten von 27 bzw. 25% Cr auch bei größeren Querschnitten nur geringe Verarmungen von 5–6% Pkt. gemessen. Bei Mo‐Gehalten von >5% wird bei Abkühlung größerer Querschnitte (200 mm □) σ‐Phasenbildung beobachtet. Zudem wurde eine Fe‐reiche kubische Phase eines bisher unbekannten Typs auf Korngrenzen beobachtet.
Some aspects on MgO solubility in complex slags
Authors: Bergman Åke 
Published: December 2016

A magnesia capacity is defined, CMg2+ = (%Mg2+)/aMgO and its relation to optical basicity is examined and discussed. The solubility of MgO in complex slags, in equilibrium with magnesiowustite, is derived from the activity of MgO in the magnesiowustite and from the magnesia capacity as given by the slag's optical basicity. It is found that the activity of MgO in the magnesiowustite can be derived from [%O] assuming ideality in the FeO–MgO system at 1600°C. It is also found that the MgO saturation contents in complex slags are accurately derived from the equation:

urn:x-wiley:01774832:srin00273:equation:srin00273-math-0001In addition, the relation between the magnesia capacity and the capacities of vanadium and phosphorus is examined and the relative basicity of the oxides is discussed.
Experiments on the smelting reduction of oxides of iron, chromium and vanadium and their mixtures with argon/methane‐plasmas
Authors: Vogel Dietmar , Steinmetz Eberhard , Wilhelmi Herbert 
Published: December 2016

The analysis of the smelted alloys and final slags reveals a preferential reduction of iron oxides. This result as well as the influence of an increasing amount of iron oxide in the mixtures on the degree of reduction, is in accordance with thermodynamic calculations.In order to give a detailed description of the kinetics of the smelting reduction, it is necessary to obtain more information on the transport properties of oxide‐ and gas phases as well as the changing partial pressures of the oxygen in melted oxides during the reduction period. Reduction of oxides with a low oxygen partial pressure, for example chromium‐, vanadium‐ and titanium oxides, by use of hydrocarbon gases mainly leads to carbon monoxide as product gas. The high temperatures reached in plasma processes increase this decomposition. Therefore, the hydrogen in the reduction gas can only be the transport medium for the main reducing agent carbon.On the other hand, high reduction temperatures favoured the kinetics of carbonmonoxide formation. Furthermore, higher temperatures lower carburization, which is a great advantage for the production of ferroalloys such as ferrochromium or ferrovanadium.The experiments show that it is possible to take advantage of thermal plasmas for melting and reducing of metal oxides and mixtures respectively, even for the high‐melting chromium oxide. It seems to be possible to melt steels with a high content of alloying elements in a one‐step procedure. For this reason, smelting reduction processes with plasma may be attractive for the production of high‐alloyed steels in small and flexible steel plants.
Investigations to determine the maximum permissible cooling velocity for ceramic components made of alumina
Authors: Honcamp Stefan , Jeschar Rudolf 
Published: December 2016

The presented paper discusses the problems of heat stress arising as a result of instationary temperature fields (thermally induced stresses) in ceramic components and includes the results of both theoretical and experimental investigations to determine the critical cooling velocity for cylindrical bodies made of alumina.The theoretical and experimental results are compared to show that calculating the stresses using the linearized elasticity theory is sufficiently accurate. The fracture condition is determined so that the fracture stress ascertained in a 4‐point‐bending experiment is defined as the maximum bearable tensile stress. The statistical theory according to Weibull is applied to transform this fracture stress onto the type of stress occurring during the cooling experiments. In addition to a short derivation of the equations for thermally induced stresses with temperature‐dependent material values, this paper also describes the determination of the relevant material values and, in particular, that of the temperature dependencies necessary for the calculation. The experimentally determined results show, in addition to the influence of the thermal diffusivity of the material, a quadratical dependence of the critical cooling velocity on the size of the body, as is also to be expected from an analytical solution to the stress equation.
Development of a numerical model simulating the desulphurisation of liquid steel
Authors: Reifferscheid Markus , Pluschkell Wolfgang 
Published: December 2016

A comprehensive numerical model is developed simulating the batch process of liquid steel desulphurisation. Special emphasis is placed on the exact figuring of real process engineering conditions. The model includes time dependent intensive parameters such as the aluminium content and the oxygen content of the liquid steel as well as the temporal course of the CaO‐, CaS, Al2O3‐component activities in the refining top slag. Mass transfer coefficients are derived from practical experience.The computations prove the outstanding influence of the stirring intensity on the rate of the refining reaction. Its progress is delayed by the dissolution of the lime charge at the beginning of the stirring treatment. The simulation model can also be applied to optimize the desulphurisation process with respect to stirring time, state of deoxidation and amount of refining slag.
Kinetic model for reduction of iron oxide in molten slags by iron‐carbon melt
Authors: Paul Amitava , Deo Brahma , Sathyamurthy Narayanasami 
Published: December 2016

Rate of reduction of iron oxide in iron and steelmaking slags by mass contents of dissolved carbon (>3%) in molten iron depends upon activity of FeO, temperature, mixing of bulk slag and other experimental conditions. A general kinetic model is developed by considering mass transfer of FeO in slag, chemical reaction at gas‐metal interface and chemical reaction at gas‐slag interface, respectively, as the three rate controlling steps. A critical analysis of the experimental data reported in literature has been done. It is shown that in the case of slags containing mass contents of less than 5% FeO, the reduction of FeO is controlled by mass transfer of FeO in slag plus chemical reaction at gas‐metal interface; when slags contain more than 40% FeO, the reduction of FeO is controlled by chemical reaction at gas‐metal interface plus chemical reaction at gas‐slag interface; at intermediate FeO mass contents (between ∼ 5 and 40% FeO), the reduction of FeO is controlled by all three steps, namely, mass transfer of FeO in slag, chemical reaction at gas‐metal interface and chemical reaction at gas‐slag interface. The temperature dependence of rate constant for the gas‐slag reaction is obtained as:In k2 = –32345.4(&6128)/ T + 19.0(&3.42); σlnk2,1/T = &0.3.where k2 is expressed in mol m‐2 s‐1 bar‐1. The mass transfer coefficient of iron oxide in bulk slag is found to vary in the range 1.5 × 10‐5 to 5.0 × 10‐5 m/s, depending upon the slag composition as well as experimental conditions.
The influence of solidification morphology on the high‐temperature mechanical properties of an 18–10CrNi steel
Authors: Scheller Piotr R. , Papaiacovou Panicos , Lin Dong‐Yih , Çöl Mustafa , Dahl Winfried 
Published: December 2016

Cylindrical specimens of the grade X4CrNi18‐10 (material no 1.4301) having diameters of 10, 15 and 20 mm were examined on a hot tensile testing unit after partial melting and cooling at different rates. Experiments were performed at temperatures between solidification and 1000°C. As a comparison non‐melted specimens taken from a continuously cast slab were investigated.In the experiments in which specimens were partially melted the radially solidified area increases with enhancing cooling rate. At cooling rates ≥ 3 K/s it accounts for more than 80 % of the specimen cross‐section. The secondary dendrite arm spacings λ2 range between approx. 30 and 50 μm at these cooling rates. As the radially solidified area increases, strength at zero‐toughness temperature decreases. At lower temperatures, on the other hand, the solidification morphology of these samples had no effect on the mechanical properties. Unlike the results achieved with partially melted specimens, with specimens taken from a continuously cast slab the solidification morphology was found to have a distinct effect. Between 1350 and 1100°C toughness is around 20 % points lower when tensile loading acts transversely to the direction of crystal growth in comparison with axial loading. On the contrary strength is slightly higher. These results show that when investigating the causes of fracture initiation and propagation during and after solidification, the solidification morphology is of prime concern.
Thermodynamics of oxygen behaviour in cobalt‐nickel alloys
Authors: Soltanieh Mansour , McLean Alex , Iwase Masanori 
Published: December 2016

In this study the concentration and chemical potential of oxygen in liquid Co‐Ni alloys equilibrated with cobalt‐nickel aluminate spinel solid solutions and alumina have been determined at 1773, 1823 and 1873K as a function of nickel concentration. The oxygen content of the melt has been measured by suction sampling and inert gas fusion analysis. The corresponding oxygen potential has been determined with the following solid state cell: Mo, Mo+MoO2 | (MgO)ZrO2 | (Co, Ni) melt + AI2O3 + (Co, Ni)O·(1+x)Al2O3, Mo.The effect of nickel on the activity coefficient of oxygen in Co‐Ni alloys has been determined. The results for the activity coefficient have been modelled with Wagner's interaction parameters and also the more recent exponential method of St. Pierre et al. at the three temperatures.
Improved relationship between Vickers hardness and yield stress for cold formed materials
Authors: Tekkaya A. Erman 
Published: December 2016

Cold‐formed metal products are increasingly serving as high duty machine parts. Designers and users need to know their properties as accurately as possible. One such product property is the new yield strength, which can be approximated by the final flow stress of the workpiece material during forming. Vickers hardness measurements provide an easy and inexpensive method of evaluating the new local yield stress in cold‐formed workpieces. The well‐known available models given in literature to convert the measured hardness number into the corresponding yield stress have an error of up to 25 %. This is basically due to the facts that cold formed material experiences large plastic strains in the main forming stage, the hardening behaviour is anisotropic and, moreover, the material properties are inhomogeneous especially at the workpiece surface. The purpose of this study is to improve the accuracy of the well‐known available correlation models between Vickers hardness measurements and yield stress. This is achieved by utilizing finite element simulations of the indentation process. The models currently incorporate only the isotropic strain‐hardening behaviour of the work material. The new suggested model decreases the theoretical conversion error to less than 10 %.The improved model has been verified by experiments. The difficulty in verifying the models is realizing an experiment with a precisely known high plastic strain. In this study, the forward extrusion process was utilized for this purpose. In the forward extrusion process there is one location in the workpiece where the plastic equivalent strain and hence the yield stress is exactly known: the axis of the extrudate. By this method it is possible to obtain strain‐hardening states up to an equivalent plastic strain of 1.6 (!). Hence, making hardness measurements at the axis of extruded workpieces, it was possible to verify the improved relationship up to realistic strain values. The results have shown that the new relationship supplies conversions with a drastically reduced error as compared to the classical relations.
Influence of silicon, aluminium, phosphorus and copper on the phase transformations of low alloyed TRIP‐steels
Authors: Traint Sandra , Pichler Andreas , Hauzenberger Karl , Stiaszny Peter , Werner Ewald 
Published: December 2016

Although silicon is very Important to prevent carbide precipitation during annealing of low‐alloyed TRIP‐steels and thus allows the austenite to be stabilized by carbon, it causes problems during processing. Therefore, other alloying elements having a similar effect as silicon have to be considered. Possible candidates to substitute or reduce silicon are aluminium, copper and/or phosphorus, which are supposed to be capable of suppressing carbide formation, too.The influence of reduced silicon contents in combination with alloying elements being capable of substituting silicon completely or partially on the phase transformations occurring during heat treatment is studied. The results of the investigations are compared with a conventional low alloyed TRIP‐steel. The phase transformations are investigated by dilatometric measurements on cold rolled material. The influence of the cooling rate after the intercritical annealing on the transformation behaviour of the austenite upon cooling and isothermal holding in the bainitic range is studied. The interpretation of the phase transformations are supported by investigations of the microstructure via light microscopy and measuring the content of retained austenite using a magnetic volumetric method.