bluuebunny/crossref_metadata_2025 huggingface dataset:
Dimensional analysis of the vertical heterogeneous buoyant plume
Authors: Ebneth Günter , Pluschkell Wolfgang
Published: December 2016

Starting from known features of homogeneous jets, the appropriate equations for the plume radius, the axial velocity and the volumetric flow capacity of the heterogeneous plume are developed by introducing a dimensionless product group. The factors and exponents connected with this group are adjusted by linear regression of data measured on water models. The own measurements show that the plume slowly performs inclinations and rotations. The limits of application for the derived equations are determined quantitatively. Here, a sufficiently low value of the gas volume fraction is decisive. The slip velocity between the bubbles and the plume is discussed. Finally, the theory is extended to the gas stirring of liquid steel. In this case, the high pressure decrease for the rising bubbles has to be taken into account.
The effect of fine precipitate particles on the creep behaviour of ferritic model steels – II. Analysis of creep results
Authors: Peterseim Jürgen , Sauthoff Gerhard
Published: December 2016

In view of efforts to develop ferritic creep resistant steels for applications above 600°C the effect of fine precipitate particles on the creep behaviour of ferritic model steels (20% Cr, up to 0.9 % Nb and 0.1 % C) was studied between 600 and 800°C as a function of stress, temperature and particle distribution. The analysis of the experimental results leads to the conclusion that the observed secondary creep rate can be described completely as dislocation creep by means of a modified power law: the temperature dependence is determined by that of the diffusion coefficient and of the shear modulus, the stress dependence is given by (σ‐σth)3where σ = applied stress and σth = threshold stress, and the effect of the particles is described exclusively by the threshold stress which is of the order of the Orowan stress.
Melting and crystallization behaviour of W‐V‐Si high‐speed steels
Authors: Dobrzański Leszek A.
Published: December 2016

Differential thermal analysis was used to determine the effects of variable Si, W and C contents on the behaviour of W‐V‐Si highspeed steels during melting and crystallization and to develop certain fragments of pseudobinary phase diagrams corresponding to melting and crystallization of these materials. Melting of S 9‐0‐2 steel involves the following sequence of transformations: reverse three‐phase eutectic reaction, direct melting of austenite grains, reverse three‐phase and then four‐phase peritectic reactions, and melting of high‐temperature ferrite. In steels containing more than 2% Si reverse four‐phase peritectic reaction occurs immediately after partial completion of reverse eutectic reaction and in steels with more than 4% Si there is also direct melting of carbides. A decrease in tungsten content from 9.5 to 7 % in steels containing 2 % Si and 1.05 or 0.9 % C enhances direct melting of austenite grains; an increase in tungsten content to 12% inhibits this reaction completely. A decrease in carbon content from 1.05 to 0.9 % in steels containing W 7‐12, V 2.5 and Si 2 % does not change the nature of transformations on melting. Crystallization of conventional S 9‐0‐2 steel involves the following sequence of events: formation of high‐temperature ferrite crystals from the liquid, three‐phase peritectic reaction, direct crystallization of austenite from the liquid, and three‐phase eutectic reaction. With silicon contents exceeding 3% direct crystallization of austenite and three‐phase eutectic reactions occur simultaneously. This sequence of reactions is not affected by reduction of tungsten content from 9.5 to 7 % in steels containing 2% Si and 1.05 or 0.9% C. An increase in tungsten content to 12% in such materials results in complete inhibition of direct crystallization of austenite from the liquid and in 1.05% C steel there is an additional change involving simultaneous occurrence of three‐phase peritectic and eutectic reactions. A decrease in carbon content from 1.05 to 0.9% in steels containing 7–12% W and 2% Si does not change the nature of transformations during cooling but does enhance partially simultaneous occurrence of three‐phase peritectic and eutectic reactions.
Model investigations on the penetration of melts into injection nozzles
Authors: You Byung‐Don , Polanschütz Wolfgang , Hiebler Herbert
Published: December 2016

The formation of gas bubbles and the penetration behaviour of the liquid into the nozzle against the gas stream were studied in water, water‐glycerine mixtures and mercury from bubbling regions to a continuous gas jet region with various nozzle configuration.

Measurements were also made with gas and powder injection in the mercury and molten pig iron models. It was observed that the penetration behaviour of the liquids during gas injection depends on the gas flow velocity, the diameter and orientation of the nozzle, the wettability and the density of the liquid. The results of the powder injection showed a lower penetration depth of the liquid into the nozzle than the results for gas only injections. The effect of each influencing factor on the penetration behaviour was shown to be similar in both injection types, with or without powder.
The effect of plate thickness on the generation of thermal stress and strain in quenched steels of high hardenability
Authors: Fletcher Alfred John , Soomro Ali Bux
Published: December 2016

A visco‐elastic‐plastic mathematical model that also incorporates transformation plasticity has been used to determine the thermal stress and strain generation in quenched plates of various thicknesses. An increase in plate thickness produced an increase in the maximum amount of absolute strain introduced during the quench. This was associated with an increase in the residual strain at the end of a water quench, but the residual strain was reduced in the case of an oil quench. Former results were in agreement with the experimental data obtained from 20 and 40 mm thick specimens.

In contrast, the level of residual absolute stress at specific points in water quenched plates fell as the thickness increased, mainly on account of the amount of stress‐relaxation in the later stages of the cooling process, as the temperature in the interior of the thicker sections fell to ambient. This effect did not agree well with the experimental results and casts some doubt on the viscous flow data used at longer times and lower temperatures. The agreement between calculation and experiment was much better in the case of the oil quenched material.
Activities of FexO in CaO + CaF2 + SiO2 + FexO quaternary slags by disposable electrochemical oxygen probes
Authors: Iwase Masanori , Akizuki Hiroshi , Ichise Eiji , Tanaka Yoshitaka
Published: December 2016

The activities of FexO in CaO + CaF2 + SiO2 + FexO quaternary slags were measured by means of solid‐oxide galvanic cell. The FexO activities in the slags are influenced by CaF2 as well as SiO2. At constant FexO mole fractions, e.g., , at low SiO2 mole fractions i.e., , the substitution of CaF2 for CaO has an effect of raising the FexO activity. At higher SiO2 mole fractions, e.g., , however, such an effect becomes insignificant.
Improving durability of ladle nozzle for continuous casting by use of spherical alumina particles
Authors: Nameishi Naoyuki , Kouchi Hiroshi , Tsuchinari Akihiro , Hattori Hisahiro
Published: December 2016

The physical properties and characteristics of unburned alumina‐carbon refractories with added spherical alumina particles were investigated. The strength of the refractories was decreased whereas the packing density, erosion resistance and thermal shock resistance were improved by the addition of the spherical alumina particles. Based on these results, the lower nozzle of the sliding nozzle for continuous casting has been made of alumina‐carbon refractories with added spherical alumina particles. The lower nozzle has shown uniform structure and reduced incidence of crack formation caused by thermal stress arising during casting. Accordingly, the durability of the lower nozzle has been considerably increased.
The rolling texture of iron of different purities
Authors: Kern Rudolf , Lee Hsiao Ping , Bunge Hans‐Joachim
Published: December 2016

Deformation texture of 90% cold rolled iron of various purities was studied by pole figure measurements from which complete orientation distribution functions ODF were calculated using series expansion including the zero range method. The texture type consists of two mutually perpendicular orientation tubes which can be idealized as (110)//RD and (111)//ND in accordance with microstructural investigations which revealed two types of microstructures corresponding to these idealized fibres. The intensity superposition of the two fibres yields a maximum density in slightly deviating positions especially in the vicinity of the intersection of the two tubes which may be idealized as (110) 30° ND fibre component. The texture of the high‐purity iron is nearest to the (111)//ND fibre. Within this general texture type, two subtypes can be distinguished corresponding to high‐purity iron on the one hand and the low‐purity materials on the other.

The texture of the high‐purity iron at 90% of deformation still corresponds to the low‐degree type of the lower‐purity materials which is attributed to the occurrence of dynamic recovery in the high‐purity iron.
Untersuchung der Eigenschaften von FeSiAl‐Elektroblechen
Authors: Büchner Achim R.
Published: December 2016

Es wurde versucht, hochlegierte Elektrobleche, deren Verlustleistungen klein, deren Kaltwalzbarkeit jedoch hinreichend gut sein soll, durch Legierungsmaßnahmen herzustellen. Dabei wurde Si teilweise durch AI ersetzt.

Im Bereich 2–3% Si und 2‐3% AI sind Legierungen zu finden, die gut kalt walzbar (im technischen Prozeß wird unter Kaltwalzen ein Walzen unterhalb etwa 180°C verstanden) sind und die die heute üblichen nichtorientierten Elektrobleche in der Verlustleistung um etwa 1/4 unterbieten sollten.
Schmelzgleichgewichte im System Fe—C—Ca
Authors: Schürmann Eberhard , Jacke Hartmut
Published: December 2016

Das binäre Randsystem Ca—Fe ist gekennzeichnet durch eine ausgeprägte Mischungslücke mit sehr geringen Löslichkeiten der beiden Elemente ineinander, während das System Ca—C durch die hochschmelzende kongruente Verbindung CaC2 und eine relativ große Löslichkeit von C im flüssigen Ca charakterisiert wird. Die durch das System Ca—C für Eisenschmelzen hervorgerufene Ca‐ und CaC2‐Sättigungslinie im ternären System Fe—C—Ca läßt sich nach thermodynamischer Auswertung der Versuchsergebnisse mit In γcca‐Werten als Funktion der Kohlenstoffkonzentration und der Temperatur beschreiben. Der Gang des Aktivitätskoeffizienten bewirkt dabei, daß die gelösten Ca‐Gehalte mit steigenden C‐Werten zunächst im Bereich der Ca‐Sättigung bis zur Doppelsättigung mit CaC2 ansteigen, anschließend im Bereich der CaC2‐Sättigung wieder abfallen, ein Minimum durchlaufen und zur Doppelsättigung mit C und CaC2 hin erneut zunehmen.
Penetrability of impinging gas jets in molten steel bath
Authors: Koria Satish C. , Lange Klaus W.
Published: December 2016

An experimental study is carried out to determine the penetrability of impinging gas jets in molten steel baths of BOF and combined blown steelmaking. Depth and diameter of the depression produced by an impinging single jet or multi‐nozzle jets are measured and correlated successfully with dimensionless momentum flow rate number. The equations are represented in the form of a nomogram by which the depth and diameter of the depression in a molten steel bath during the blow can be determined from easily available top blowing parameters.
Untersuchungen zum Hydratationsverhalten von synthetischen Magnesiowüstiten
Authors: Geiseler Jürgen , Schlösser Ruth , Scheel Rüdiger , Koch Klaus , Janke Dieter
Published: December 2016

Eine ausreichende Raumbeständigkeit ist die notwendige Voraussetzung für die Verwendung von Stahlwerksschlacken als Baustoff mit höheren qualitativen Anforderungen im Straßenbau. Die Raumbeständigkeit kann durch Mineralphasen gefährdet werden, die mit Feuchtigkeit unter Volumenzunahme hydratisieren. Zu den hydratisierbaren Mineralphasen zählen Freikalk und in MgO‐reichen Schlacken auch bestimmte MgO‐Phasen. Mikroskopische Untersuchungen an MgO‐reichen LD‐Schlacken zeigen, daß das MgO größtenteils in Form von Magnesiowüstiten – Mischkristallen zwischen MgO und FeO/MnO – gebunden vorliegt. Während reines MgO hydratisierbar ist, verhalten sich FeO und MnO inert gegenüber Feuchtigkeit.

Anhand von synthetisch hergestellten Magnesiowüstiten unterschiedlicher Zusammensetzung wurde geprüft, welche Mischkri‐stalle als hydratisierbar einzustufen sind. Dazu wurden Hydratationsversuche bei unterschiedlichen Temperatur‐/Druck‐Bedin‐gungen durchgeführt. Bei 84°C/0,53 bar war zur Stabilisierung der Magnesiowüstite ein (FeO + MnO)‐Gehalt von 30% notwendig, bei 215°C/21 bar lag dieser Gehalt bei 60%. Da sich die Bedingungen bei der Prüfung im Labor von denen in der Straße deutlich unterscheiden, ist die Festlegung eines (FeO + MnO)‐Grenzgehalts, durch den Magnesiowüstite unter den in einer Straße herrschenden Bedingungen stabilisiert werden, zur Zeit noch nicht möglich. Solange die Übertragbarkeit der Laborergebnisse auf die Praxis noch nicht nachgewiesen ist, wird der unter den sehr scharfen Autoklavbedingungen ermittelte MgO‐Grenzgehalt von 40% zugrunde gelegt. Als hydratisierbares MgO – oder auch MgOfrei in Analogie zu CaOfrei – werden somit ungebundenes MgO und Magnesiowüstite mit > 40% MgO bezeichnet.
Untersuchungen zum Einfluß höherer Mo‐Gehalte auf das Korrosionsverhalten von höherfesten nichtrostenden ferritisch‐austenitischen Stählen
Authors: Tacke Gerhard , Köhler Heinz Jürgen
Published: December 2016

An geschmiedeten Proben unterschiedlicher Wärmebehandlungsquerschnitte aus ferritisch‐austenitischen Stählen mit 20–28% Cr, 1,5–6% Mo, ca. 5% Ni, bis ca. 1,5% Cu und bis zu je 0,25% Nb, V und N wurden Untersuchungen auf interkristalline Korrosion, Lochtraß‐ und Spaltkorrosion in Cl‐haltigen Medien, Salpetersäurebeständigkeit und Spannungsrißkorrosion durchgeführt. Die Untersuchungsergebnisse sind wie folgt: Die untersuchten Stähle erwiesen sich selbst bei größeren Mengen an Ausscheidungen auf den Korn‐ und Phasengrenzen als beständig gegen interkristalline Korrosion im verschärften Strauß‐Test. Ursache hierfür ist die unkritische Cr‐Verarmung aufgrund der verhältnismäßig geringen Cr‐Abbindungsrate in den auftretenden Nitridmodifikationen. Die Lochfraß‐ und besonders die Spaltkorrosionsbeständigkeit gegen Cl‐Ionen wird ab 3,2% Molybdän sprungartig verbessert. Ab ∼4% Mo führt die zunehmende Ausscheidungsmenge besonders bei größeren Wärmebehandlungsquerschnitten wieder zu einem Rückgang der Spaltkorrosionsbeständigkeit. In konzentrierter siedender HNO3nimmt die Materialverlustrate mit zunehmendem Mo‐Gehalt und mit sinkender Abkühlgeschwindigkeit, entsprechend steigendem Wärmebehandlungsquerschnitt, infolge erhöhter Ausscheidungsmenge auf den Korngrenzen zu. Das SpRK‐Verhalten zeigt keine bemerkenswerte Abhängigkeit vom Mo‐Gehalt.

Ein ferritisch‐austenitischer Stahl mit rd. 25% Cr, 3,5% Mo, 5% Ni und festigkeitssteigernden Legierungszusätzen von Nb, V, N, der auch Cu‐Gehalte von über 1% enthalten kann, weist bei gleichen Festigkeitskennwerten wie X 4 CrNiMoNbVN 27 6 2 wesentlich verbesserte Cl‐lonenbeständigkeit auf. Der auf 0,03% begrenzte C‐Gehalt gewährleistet IK‐Beständigkeit im verschärften Strauß‐Test. Dieser Stahl, der die Bezeichnung X 3 CrNiMoNbVN 25 6 4 (Werkstoff‐Nr. 1.4530) trägt, wurde in der Zwischenzeit vorwiegend in Schmiedestücken mit Wanddicken bis zu ca. 180 mm für chemisch und mechanisch hoch beanspruchte Teile im Maschinenbau eingesetzt.
The effect of retained austenite on the fracture toughness of high‐speed steels
Authors: Pacyna Jerzy
Published: December 2016

The aim of this work was to find the quantitative dependences between fracture toughness Klc and the volume fraction of retained austenite in the matrix of quenched high‐speed steels. The tests were carried out on three model alloys of a different content quotient of Mo: W which, after quenching, were gradually supercooled up to − 196°C and then tempered at 450°C. Also the measurements of the content of retained austenite in the vicinity of the surface of a sample fracture were carried out. It was determined that after tempering at 450°C the fracture toughness of the matrix of high‐speed steels is directly proportional to the content of retained austenite in it. Every 1 % by volume of retained austenite increases the fracture toughness Klc of the matrix by about 5%, despite the fact that most probably it is completely transformed into fresh martensite in front of a propagating crack.

Higher fracture toughness of the matrix of high‐speed steels rich in molybdenum should be explained exlusively by a larger content of retained austenite. Transformations in the martensitic part of the matrix of the alloys richer in molybdenum clearly reduce the advantageous effect of retained austenite on this steel feature.
Die Ursache für die drastische Steigerung des Beizabtrages bei Emaillierstahlblechen durch Schwefelwasserstoff
Authors: Dietzel Adolf , Dittmer Helene
Published: December 2016

An Reinsteisen in Schwefelsäure wurden eine hohe Wasserstoffüberspannung und ein verhältnismäßig niedriger Beizabtrag gefunden. Durch Einleiten von H2S in die Säure erniedrigte sich die Überspannung erheblich, und der Beizabtrag wurde erhöht. Im Gegensatz dazu zeigte ein übliches Emaillierstahlblech keine Wasserstoffüberspannung; hier genügte offenbar der aus dem Stahlblech entstehende naszierende Schwefelwasserstoff, um den Beizabtrag gegenüber Reinsteisen zu erhöhen. Diese Wirkung des Schwefelwasserstoffes beruht auf der Beseitigung des atomaren, an der Blechoberfläche adsorbierten und den Säureangriff hemmenden Wasserstoffes. H2S wird dadurch nicht verbraucht, sondern reichert sich im Gegenteil durch die Stahlauflösung in der Säure an bis zu einer Grenze, die durch die Verflüchtigung gegeben ist. Es handelt sich also um eine Autokatalyse. Der wahrscheinliche Reaktionsmechanismus wird diskutiert.

Diese Zusammenhänge erklären die in vorangehenden Arbeiten gemachten Beobachtungen über die starke Erhöhung der Beizabträge durch Schwefelwasserstoff bzw. Sulfide. Die bekannte Grenze für das Cu/S‐Verhältnis = 2 nach T. P. Hoare und D. J. Havenhand hinsichtlich der Korrosionsbeständigkeit von einfachen Stählen läßt sich nach den vorliegenden Befunden einfach erklären.

Auf die Doppelrolle des Sulfidschwefels beim Beizen (beizfördernd bzw. beizhemmend als Inhibitor) wird kurz eingegangen.
Effects of boron on the creep properties, phosphorus segregation behaviour, and stress relief cracking susceptibility of 1.5% Cr–0.5% Mo steels
Authors: Sato Shingo , Grabke Hans Jürgen
Published: December 2016

The effects of 25 ppm boron and of 0.05% phosphorus on the creep behaviour at 550 °C and on the fracture temperature in the constant load fracture test were tested for a 1.5% Cr–0.5% Mo steel. B and P decrease the creep strength, the rupture elongation is increased by B. B and P lower stress relief cracking susceptibility, however, it is increased at low stress. In the B doped material the rate of P grain boundary segregation is accelerated and the level of equilibrium segregation is somewhat higher, the equilibrium segregation is somewhat lower in the bainitic than in the martensitic structure.
Theoretical treatment of interaction parameters in multicomponent metallic solutions
Authors: Ueno Shuji , Waseda Yoshio , Jacob K. Thomas , Tamaki Shigeru
Published: December 2016

A new theoretical equation for interaction parameter in multicomponent metallic solutions is developed using the pseudopotential formalism coupled with the free energy of the hard sphere system. The approximate expression for the pseudopotential term is given in terms of the heat of solution at infinite dilution, to allow easy evaluation of the interaction parameter in various multicomponent systems. This theory has been applied to 23 non‐ferrous alloys based on Pb, Sn, Bi and In. Comparison with the results of previous theoretical calculations using only the hard sphere model suggests that the inclusion of the pseudopotential term yields a quantitatively more correct prediction of interaction parameters in multicomponent metallic solutions. Numerical calculations were also made for 320 Fe‐base solutions relevant to steelmaking and the agreement between calculation and experimental data appears reasonable, with 90% reliability in predicting the correct sign.
Theoretical and practical aspects of tube sinking by a rotary die
Authors: Sadok Lucjan , Urbański Stanisław
Published: December 2016

This paper is concerned with a method of analyzing the process of tube sinking by a rotary die, modifying the method of finite elements. The components of the state of strain tensor have been determined for the conventional tube sinking process as well as a rotary die. It has been proved that the adoption of a rotary die does not essentially change the scheme of the state of strain, but that it does, however, reduce the drawing force. The results of theoretical analysis have been compared with those of experimental tests effected by means of a special device ensuring die rotation.
Nitrogen desorption from pure iron melts under reduced pressure
Authors: Harada Toshiya , Janke Dieter
Published: December 2016

More recently, lower nitrogen contents of steel are required in view of its workability and applicability. The present study covers basic investigations on the improvement of mass transfer in denitrogenation of steel melts under vacuum. Extensive reduction of the contents of the surface‐active elements oxygen and sulfur is a precondition to increase the rate of nitrogen desorption. Kinetics of nitrogen transfer is reliably described by a mixed control model which includes diffusion in the melt, interfacial reaction and diffusion in the gas phase. Particularly at low oxygen and sulfur contents, mass transfer of nitrogen during desorption from steel melts is markedly accelerated. A convincing explanation of this phenomenon has not been found yet.
Dauerschwingverhalten nichtrostender Stähle unter gleichzeitiger korrosiver Beanspruchung, Teil 1: Verhalten bei erhöhten Temperaturen und in korrosiver Heißgasatmosphäre
Authors: Roeder Erwin , Schumacher Gerald
Published: December 2016

In einer Übersicht werden die bislang am Lehrstuhl für Werkstoffkunde und Mechanische Technologie der Universität Kaiserslautern durchgeführten Untersuchungen des Dauerschwingverhaltens nichtrostender Stähle vorgestellt.

Es wird eine Prüfeinrichtung beschrieben, mit der das Schwingverhalten metallischer Werkstoffe bei erhöhten Temperaturen bis zu 700°C bei gleichzeitiger Einwirkung heißer Gase ermittelt werden kann. Für die mit dieser Apparatur untersuchten hochlegierten Stähle X 5 CrNi 18 9 (1.4301), X 10 CrNiMoTi 18 10 (1.4571) und X 5 CrTi 12 (1.4512) ist die Verringerung der Schwingfestigkeiten in erster Linie durch die erhöhte Versuchstemperatur bedingt. Der zusätzliche festigkeitsmindernde Einfluß der korrosiven dampfförmigen Phase eines Modellkondensates bzw. H2O‐HCI‐Gemisches ist bei den gegebenen Versuchsbedingungen vergleichsweise gering. Bei Betriebsfestigkeitsuntersuchungen mit verschiedenen Beanspruchungskollektiven ergeben sich für den Stahl 1.4571 bei allen Versuchstemperaturen die kürzesten Lebensdauern erwartungsgemäß für den reinen Einstufenversuch (Wöhler‐Versuch).
The ring compression test as simulation test for the investigation of friction in hot metal forming
Authors: Pawelski Oskar , Rasp Wolfgang , Hoerster Christoph
Published: December 2016

Forces and flow of material in metal working decisively depend on friction between workpiece and tool, which can be described by the friction factor m. For investigation of the influence of friction in hot forming of steel and for measurement of the friction factor, the ring compression test is used as simulation test. The influences of material, reduction, strain rate, temperature, and lubricant are discussed.
Dauerschwingverhalten nichtrostender Stähle unter gleichzeitiger korrosiver Beanspruchung, Teil 2: Schwingungsrißkorrosionsverhalten
Authors: Roeder Erwin , Schumacher Gerald
Published: December 2016

In dieser Arbeit werden die bisher am Lehrstuhl für Werkstoffkunde und Mechanische Technologie der Universität Kaiserslautern durchgeführten Untersuchungen auf dem Gebiet des Schwingungsrißkorrosionsverhaltens nichtrostender Stähle dargestellt.

Eine Prüfapparatur zur Durchführung von Dauerschwingversuchen bei kontrollierter elektrochemischer Korrosion wird beschrieben. Die dynamischen Festigkeitskennwerte des untersuchten Stahles X 5 CrTi 12 (1.4512) liegen bei überlagerter Korrosion durch das Modellkondensat wesentlich unter den an Luft ermittelten Werten. Eine Dauerschwingfestigkeit kann erwartungsgemäß nicht bestimmt werden. Der Einfluß der Elektrolyttemperatur von maximal 80°C auf die Schwingfestigkeit ist bei den gewählten Versuchsparametern von untergeordneter Bedeutung. Durch Messung des zeitlichen Verlaufs des freien Korrosionspotentials kann ein Zusammenhang zwischen der Lebensdauer der Schwingproben und der Länge der sich einstellenden Potentialstufen festgestellt werden. Durch Aufprägen geeigneter elektrochemischer Potentiale im potentiostatischen Halteversuch ist eine deutliche Erhöhung der Zeitschwingfestigkeit gegenüber dem unkontrollierten Zustand möglich.
The characteristics of certain experimental quenching oils
Authors: Allen Frances Sarah , Fletcher Alfred John , Mills Alan
Published: December 2016

An examination has been made of the effect of certain additives on the quenching characteristics of a typical medium quenching oil. One additive, sodium sulphonate, increased the maximum surface heat transfer coefficient produced during the quench and reduced the temperature at which this occurred. The other, an ashless additive, increased the maximum surface heat transfer coefficient by a slightly smaller amount, but raised the temperature at which this occurred. The implications of these results are discussed in relation to thermal cracking, distortion and the ability of the quenchant to produce a fully martensitic structure during the quench.

A photographic study of the appearance of the quenchant in the vicinity of the cooling plate is also reported, together with selected physical properties of the oil. The number and size of irregularities on the surface of the vapour blanket was increased by both additives, as was the amount of vapour produced during nucleate boiling. The most significant change in the physical properties took place in the temperature range over which distillation of the oil occurred.
Determination of nitrogen and carbon interstitially dissolved in continuously‐annealed steel sheets by means of a fully automatic torsion pendulum
Authors: Borst Gerhard
Published: December 2016

A fully automatic torsion pendulum of the Collette type was built to test continuously‐annealed steels in the thickness range between 0.15 and 0.4 mm for their contents of dissolved nitrogen and carbon. The influence of composition and production conditions on unalloyed steels which had been annealed commercially and in the laboratory were investigated. It was found that, with an increase in the total carbon and aluminium contents, the percentages of the dissolved nitrogen and carbon decrease, whereas higher nitrogen contents resulted in an increase of the percentages dissolved. A higher coiling temperature of the hot band leads to a decrease in the nitrogen dissolved due to the formation of AIN, but to an increase of the carbon dissolved. As these effects almost compensate each other, the coiling temperature is not a suitable means to influence the aging potential. During the continuous annealing process, temperatures of more than 750°C result in a decrease of the nitrogen dissolved, which is completely precipitated as AIN leaving the carbon content nearly unaffected. No major differences were observed, when the material was annealed either with or without a subsequent overaging treatment. However, rapid cooling to low temperatures definitely increased the percentages of elements dissolved.
Investigations of drop‐size‐distribution and mass transfer in gas‐stirred liquid‐liquid systems
Authors: Frohberg Martin G. , Gerlach Friedemann , Handschuh Georg
Published: December 2016

In cold model experiments of a bottom blown converter containing water and oil in different ratios the size distribution of the dispersed oil drops were measured directly by a special suction probe method. The computerized evaluation yields the relative frequencies of the drops in diameter classes versus the drop diameter. It was observed that increasing gas flow rates produce decreasing drop diameters. The type of the statistical function which describes the drop‐size distribution leads to the conclusion that the bottom blown dispersion mechanism is comparable to a hydropneumatic mill. The total distribution was calculated from three‐dimensional measurements. Under the experimental blowing conditions the overall transfer area exceeds that of the non‐stirred system by the factor 15. Additional measurements show the effect of changed conditions of the oil fraction and the interfacial tension.

The second part of the investigation deals with measurements of the mass transfer of caprylic acid under dispersion conditions. The product of the transfer coefficient and the transfer area as an expression of the velocity of mass transfer increases with increasing gas flow rates in three ranges of different slope. An interpretation is given for this observation. Our own values of mass transfer velocity are comparable with industrial results of final decarburization in the bottom‐blown converter. Together with separate experiments with non‐disturbed interfaces it was found that the mass transfer is accelerated by a factor 10 to 100, according to the blowing conditions.
Spannungsverteilung in der berohrten Kesselwand eines Konverterkühlkamins
Authors: Gudenau Heinrich Wilhelm , Dahl Winfried , Koerfer Markus , Scheiwe Michael
Published: December 2016

Derzeit existieren keine Möglichkeiten, Wärmespannungen in dünnwandigen Kesselrohren auf Basis gemessener Wandtemperaturen zu berechnen, oder die Spannungen direkt meßtechnisch zu erfassen. Durch die Anwendung der Finite‐Element‐Methode ergibt sich die Möglichkeit, unter Berücksichtigung einer geeigneten Modellgeometrie instationäre Temperaturfelder in den Kesselrohren zu berechnen, welche eine zweidimensionale Spannungsanalyse unter Beachtung des plastischen Verhaltens des Rohrwerkstoffs ermöglichen. Für diese Temperaturverteilung erreichen die instationären Vergleichsspannungen nach von Mises in der Anfahrphase und während der Blasphasen die Streckgrenze des Werkstoffes von ReL = 264 N/mm2. In der gesamten Struktur überwiegen dabei Druckspannungen. Die resultierenden Gesamtdehnungen sind in x‐ und y‐Richtung stets positiv und in z‐Richtung, in Folge restriktiver Randbedingungen, Null. Der Werkstoff verhält sich nach einmaligem Eintritt in die Blasphase quasi‐elastisch.
Fracture mechanical assessment of pipes under quasistatic and cyclic loading
Authors: Roos Eberhard , Diem Harald , Herter Karl‐Heinz , Stumpfrock Ludwig
Published: December 2016

Methods will be outlined which allow the calculation of the load‐bearing capacity of circumferentially cracked pipes. The reliability of the calculating procedures are checked by means of appropriate tests with pipes (DN 400) under internal pressure and with a superimposed bending moment. The loading conditions may be static as well as cyclic. The cyclic crack growth experiments were performed at the HDR test facility. Under quasistatic loading conditions the failure behaviour of pipes with through‐wall cracks were calculated on the safe side. The cyclic experiments showed the decisive influence of the environmental conditions on the crack growth rate.
Influence of modern melting techniques on the creep behaviour of heavy‐section components of 1% CrMoV steels
Authors: König Hermann , Mayer Karl‐Heinz , Keienburg Karl‐Heinz , Grabke Hans‐Jürgen , Gärtner Eva
Published: December 2016

By following new paths in steel metallurgy the quality of heavy‐section components of 1% CrMoV steels, such as turbine rotors for fossil‐fired steam‐power plants, has been continuously improved. The objective of this paper is to study the influence of modern steel‐making processes on creep behaviour at 500 and 550°C using specimens taken from the rim and core zones of turbine rotors manufactured during the past ten years.

While an influence of the steel‐making process on creep‐rupture strength could not be established, the creep‐rupture strength and the creep strength for 1% creep strain were found on average to be 20% higher than the recommendations of SEW 555. In the VCD‐treated melts a creep strain of 1% was achieved earlier (time factor 2 to 3) than in melts treated otherwise.

Particularly the VCD‐treated melts are characterised by high creep ductility (reduction of area after creep rupture). But also the other melts were found to achieve a higher creep rupture ductility than in the past. This is mainly due to a lower content of residual elements as well as optimised heat treatment.
Influence of oxide scales on heat transfer in secondary cooling zones in the continuous casting process, part 2: determination of material properties of oxide scales on steel under spray‐water cooling conditions
Authors: Slowik Jacek , Borchardt Günter , Köhler Christian , Jeschar Rudolf , Scholz Reinhard
Published: December 2016

In order to model heat transfer from the slab to the cooling agent in the continuous casting process the thermophysical properties of the surface layer must be taken into account. For this purpose thermal conductivities and thermal diffusivities of wustite as well as of two carbon steels were measured. The oxide scale growth for six steels was measured as a function of time and at temperatures between 900 and 1200°C in air and in steam. Complex heterogeneous oxide scales were examined by optical and scanning electron microscopy, by SIMS, as well as by Mössbauer spectroscopy. Segregation of alloying elements in the metal‐oxide contact zone was found. Cracks due to thermal stresses result in spalling of the scale. Therefore, a straightforward use of the data for process modelling can principally not be recommended without restrictions.
Simple model for thermal calculation in twin‐roll strip casting process
Authors: Takuda Hirohiko , Hatta Natsuo , Teramura Masayuki , Kokado Jun‐ichi
Published: December 2016

The numerical model for the solidification process of metal in the twin‐roll type strip caster is presented in this paper. In the model the temperature change as well as the eliminating process of latent heat is calculated along the stream lines obtained by a comparatively simple velocity field. The calculations are carried out on the strip casting of type 304 stainless steel under various casting parameters. The results so obtained show a good fit to the experimental ones, and suggest that the control of the height of molten pool is of importance to the establishment of the optimal operation.
Reduction of slab stock by application of natural spread in the hot rolling of plate
Authors: Lundberg Sven‐Erik , Holmberg Anders
Published: December 2016

In recent years new technologies such as Hi‐spread and heavy‐edge reductions have been established, in order to achieve a hot link. These technologies are mostly not applicable in existing mills. Hi‐spread technology also reduces the number of slab sizes and thus the slab stock. However slab stock can be reduced to some extent by utilizing the natural spread in rolling.

The spread mechanism is quite complex and spread is influenced by roll‐gap geometry, the friction in roll gap and by the plastic properties of rolled material. The influence of friction and roll‐gap geometry are closely connected and have been fairly well investigated earlier, while the influence of plastic properties of rolled material on spread still is unknown.

By deduction of a new spread formula and establishment of criteria for edge rolling necessary to obtain plate with straight edges, it was possible to reduce the slab stock for rolling of plate by in order of 10% at Ovako Steel Profiler AB in Luleå.
Some aspects of development of models for automatic control of rolling mills
Authors: Pietrzyk Maciej , Kusiak Jan , Glowacki Miroslaw
Published: December 2016

Computer‐aided rolling‐technology design is presented in the paper. Program is based on the solution of the set of non‐linear equations which describe the process. They include continuity equations and power balance equations for continuous rolling. Reverse rolling is described by constant‐rolling‐force equations and power‐balance equations for both main drive and reel drives. Typical results of calculations for hot and cold rolling processes are presented.
Temperature‐enthalpy diagrams of different operating methods in blast‐furnace processes
Authors: Bittner Hans‐Georg , Weineck Sabine
Published: December 2016

This report is concerned with the representation of temperature profiles for gas and solid in temperature‐enthalpy‐diagrams for the example of the blast‐furnace process. Of particular interest is the point at which the gas and solid temperatures approach each other the most. For this, the temperature profiles for gas and solid are required, which can both be represented as a function of the specific enthalpy of the solid. With such diagrams we are able to judge the effects on process changes with reference to the position and the level of the minimum temperature difference between gas and solid, and to the level of the top‐gas temperature and the caloric temperature dominating in front of the air‐blast tuyères. In this context the influence of the coke ratio, of the furnace blast temperature, of the oxygen enrichment of the furnace blast, of the specific heat losses, as well as of the injected replacement fuels was studied for the example of pulverized coal and heavy oil. As a rule, the minimum temperature difference is to be found at the beginning of the smelting of the burden. Depending on the change of the process quantities the temperature difference can also arise at the top, as for example during oxygen enrichment.
Analytical solutions for steady and non‐steady heat conduction with temperature dependent material values
Authors: Jeschar Rudolf , Alt Rüdiger
Published: December 2016

A transformation well‐known for a long time is used to transform the differential equation for heat conduction for temperature dependent material values into a differential equation written in a more simplified form. It is investigated how the initial and boundary conditions are transformed and in which cases the problem with variable material values can be solved by applying the solutions known for constant material values. For constant thermal diffusivity, this reduction is possible for boundary conditions of the first and second kind without limitation, for conditions of the third kind only in some cases. The results of different methods of calculation are compared in an example calculation. The series solution with transformation lies generally much closer to the numerically calculated temperature than the solution without transformation. The computing times for the series solution with transformation are reduced by a factor of 100. If the first minutes of the heating period are disregarded, the first term constitutes an excellent approximation. The computing time for the finite‐difference method with transformation is 20% lower than without transformation.
Temperature compensation in heated solids
Authors: Specht Eckehard , Alt Rüdiger
Published: December 2016

Workpieces, which are removed from the furnace in a hot state for further processing, require generally a temperature as uniform as possible. The actual heating time is following therefore by a compensation phase. Analytical equations for the compensating times in slabs, cylinders and spheres are derived for the ideal case of an adiabatic solid, which is often a good approximation in practice. In technical processes, the compensating time is only marginally dependent on the temperature distribution existing at the onset of the compensation period. The compensation process is the longest in the slab and the shortest in the sphere, and lasts longer the larger the penetration depth for the temperature charge in the solid is.
Slag corrosion of dolomite‐carbon refractories
Authors: Le Coq Xavier , Dupré Bernard , Gleitzer Charles , Adam Robert , Scheidt François , Tassot Patrick
Published: December 2016

Seven industrial doloma refractory samples, coming from three European suppliers, and with different carbon, or graphite, or binder content, are subjected to the action of a slag required for the desulfurization of the steel in the secondary metallurgy at 1600°C. Three tests have been carried out within two induction furnaces. The corrosion depth, at the slag‐steel interface, has been measured; the graphite‐containing samples display a better resistance than the graphite‐free pitch or resin‐bonded refractories. Among the graphite‐containing samples correlations have been found with the carbon content and with the resistance to oxidation by CO–CO2 at 1100–1200°C. The slag‐refractory interface has been investigated by X‐ray diffraction, optical microscopy and electron microprobe analysis; the observed phases are CaO, MgO, Ca2SiO4, Ca3SiO5 and Ca12Al14O33 (outside graphite and iron). The corrosion mechanism is linked to the reaction of slag with lime, followed by infiltration of the refractory and dispersion of periclase grains in the slag.
Testing and applications of a process model in the metallurgical production practice of ferronickel from laterites
Authors: Papamantellos Demetrios C. , Angelopoulos George N. , Mavrommatis Konstantinos T.
Published: December 2016

A mathematical model of the electro‐reduction furnace process (ERF process), for the production of ferronickel from laterite ores, has been tested at Larco's metallurgical plant at Larymna Greece. The theoretical predictions for the progress of the nickel reduction have been compared with the operational results. The tests were carried out in the ERF no. 2 of Larco's plant. The influence of the main process variables on the nickel recovery and nickel losses in the ERF slags have been investigated in conjunction with the variation of the analysis of the feed and the nickel content of the metal bath. The further application of the model to the metallurgical practice is discussed. According to the predictions of the model the further development of the process in the direction of the production of low‐nickel ferronickel (Ni < 15%) is analyzed. The advantages of the production of low‐nickel ferronickel are presented and the possibility of its straight conversion to nickel‐bearing steel‐grades is discussed.
Finite element based model of structure development in the hot rolling process
Authors: Pietrzyk Maciej
Published: December 2016

An existing thermomechanical finite‐element model of the hot rolling process is used to simulate the structure evolution in the strip. The equations which describe the grain‐size variations during the hot deformation are implemented in the model. The local values of temperatures, strain rates and strains are used in calculations, allowing the determination of the grain‐size distribution across the strip. The results of calculations carried out for the seven‐stand hot‐strip mill are presented in this paper.
Rolling and recrystallization textures of bcc steels
Authors: Hölscher Martin , Raabe Dierk , Lücke Kurt
Published: December 2016

The rolling and recrystallization texture development of bcc steels is discussed for three examples belonging to three different types of steels, namely deep drawing steels (e.g. low carbon steel), ferritic stainless steels (e.g. Fe16%Cr) and electrical steels (e.g. Fe3%Si).
Experimental study of the effect of gas injection parameters on the bath mixing intensity induced during steelmaking
Authors: Koria Satish C. , Pal S.
Published: December 2016

The present study is concerned with the evaluation of the bath‐mixing intensity induced by gas injection during steelmaking. The rate constant for the process of mass transfer between the two cold‐model simulated immiscible liquids (water/oil) is employed as the criterion of judgement of bath‐mixing intensity. Gas is either injected from the bottom alone or simultaneously from top and bottom. Bath‐mixing criterion is successfully correlated with the mixing power. Increase in bottom injection rate is found to increase the rate constant. In the simultaneous injection lance distance, and top and bottom gas‐injection rates are shown to be the relevent independent dynamic parameters. From the comparison of the rate constants between pure bottom and simultaneous injection and pure top and simultaneous injection, it is asserted that the simultaneous injection provides more operational flexibility, better control of slag formation and refining rates as per blow requirements and steel grades. However, some minimum gas is required to realize the operational benefits.
Heat and mass transfer limitations in gasification of carbon by carbon dioxide
Authors: Bandyopadhyay Debajyoti , Chakraborti Nirupam , Ghosh Ahindra
Published: December 2016

Rates of gasification of carbon by carbon dioxide were measured in the laboratory using a thermogravimetry apparatus. The experiments were conducted at various temperatures and sample bed depths using powders of graphite and coconut char as sources of carbon, under flowing gas of CO2. Various CO–CO2 mixtures were also employed for the study of coconut char. The measured rate data were subjected to a heat and mass transfer analysis to find out the values of isothermal and non‐isothermal effectiveness factors. These values were utilized to predict the intrinsic chemical reactivities of graphite and coconut char samples, free from heat and mass‐transfer limitations. Extrapolation of experimental data to hypothetical zero bed depth showed good agreements with the above at various temperatures, thus providing valuable cross‐checks. The activation energies were found to be 260 and 250 kJ/mol for graphite and coconut char, respectively, under CO2. Carbon monoxide was found to decrease the rate of gasification but not as drastically as some literature reports predict.
A mathematical model of single roll strip caster based on macroscopic enthalpy balances
Authors: Kumar Anjan , Mehrotra Surya Pratap
Published: December 2016

A mathematical model, based on the overall heat balance and the growth of solidification front, has been formulated to describe the single‐roll strip‐casting process for steel. The model provides useful interrelationships between the rate of growth of solidifying strip and the principal process variables such as the speed of rotation of caster drum, the system geometry, the superheat of melt and the relevant heat transfer coefficients. Using these relationships it has been possible to predict the effect of process parameters on the process performance in terms of the final strip thickness and the casting rate.