bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
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).
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.
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.
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.
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.
Entwicklung, Eigenschaften und Anwendung von konventionell erzeugten hochstickstoffhaltigen austenitischen Stählen
Authors: Gillessen Christoph , Heimann Winfried , Ladwein Thomas L. 
Published: December 2016

Durch legierungstechnische Maßnahmen lassen sich mit konventionellen Verfahren (Elektrolichtbogenofen, AOD‐/VOD‐Anlage) hochstickstoffhaltige austenitische Stähle erzeugen, die im lösungsgeglühten Zustand beachtliche Eigenschaften aufweisen. Die Wirkungen des Stickstoffs sind eine Erhöhung der Festigkeit durch Mischkristallverfestigung (und Auscheidungshärtung bei Amagnit 3974 (X 3 CrNiMnMoNbN 23 17 5 3)), eine Erhöhung der Austenitstabilität, die Verzögerung von Ausscheidungsvorgängen sowie eine Verbesserung der Loch‐ und Spaltkorrosionsbeständigkeit.Nach der Entwicklung von hochfesten unmagnetischen Stählen führte die Legierungsoptimierung zu dem Werkstoff Remanit 4565 S (X 2 CrNiMnMoN 24 17 6 4), der bei hoher Festigkeit eine ausgezeichnete Beständigkeit in zahlreichen Medien aufweist. Aufgrund des günstigen Einflusses von Stickstoff weist dieser Stahl mit nur 4,5 % Molybdän eine höhere Wirksumme PRE und eine höhere Beständigkeit gegen Loch‐ und Spaltkorrosion auf als die gängigen 6%‐Mo‐Austenite. Das Schweißen der beschriebenen hochstickstoffhaltigen Stähle ist ohne besondere Vorkehrungen mit allen üblichen Verfahren möglich. Porenbildung tritt nicht auf. Mit dem empfohlenen Schweißzusatz Thermanit NimoC (SG‐NiCr 20 Mo 15) lassen sich mit dem WIG‐ und dem UP‐Schweißen an Remanit 4565 S (X 2 CrNiMnMoN 24 17 6 4) Verbindungen herstellen, die ebenso beständig gegen Loch‐ und Spaltkorrosion sind wie der Grundwerkstoff. Somit steht mit Remanit 4565 S (X 2 CrNiMnMoN 24 17 6 4) eine vielseitige wirtschaftliche Alternative zu 6 %‐Mo‐Stählen und Nickelbasislegierungen zur Verfügung.
Physical properties in the temperature range from –180 to 400°C of nickel alloy steels for low‐temperature applications
Authors: Richter Friedhelm , Hemminger Wolfgang , Hanitzsch Erich 
Published: December 2016

Nickel, which is the second neighbour to iron in the periodic table of elements, has a significant effect on most of the physical properties of the steels studied here, with the nickel content of the steels varying between 3 and 9%. Density and coercive force increase as the nickel content in the steel increases. By contrast, thermal expansion, modulus of elasticity and shear modulus decrease with increasing nickel content.Because of large scatter in the data, it is not possible to notice any significant influence of nickel content on Poisson's ratio and bulk modulus. Specific heat is also found not to vary with the nickel content of the steel. Electrical resistivity and thermal resistivity values increase, as expected, with increasing nickel content. The results of thermal conductivity measurements on 12 Ni 19 and X 8 Ni 9 have led to the development of modified Smith‐Palmer relationships, which allow the calculation of the thermal conductivity values for the present set of steels and other steels with similar compositions.
Experimental studies on the flow velocity of molten metals in a ladle model at centric gas blowing
Authors: Xie Yongkun , Oeters Franz 
Published: December 2016

Experimental measurements of the flow velocity were carried out with liquid Wood's metal in a ladle‐shaped vessel with an inner diameter of 40 cm at centric gas blowing. By means of permanent magnet probes the liquid flow field was measured under various blowing conditions. The results show that a circulating flow field is established in the vessel. In the bubble plume zone an upwardly directed liquid flow is formed. The radial distribution of the flow velocity in this zone follows a Gaussian function. The axial flow velocity increases with growing gas flow rate and is nearly constant in vertical direction. The width of the upward flow becomes larger with increasing distance from the nozzle and its dependence from the gas flow rate is not considerable. At centric gas blowing the liquid in the upper part of the bath streams quickly, whereas in the lower part so‐called “dead zones” with very low flow velocity are present.Besides the time‐averaged value of the flow velocity, the turbulent behaviours of the liquid flow such as fluctuation velocity, the turbulent kinetic energy and its dissipation rate were investigated on the basis of measured data. It was found that the liquid flow is turbulent particularly in the region of bubble plume and of bath surface. The radial profiles of these parameters can also be described by a Gaussian function. Only a small part of the gas stirring energy is changed into the kinetic energy of the directed liquid flow. Most of the stirring energy is already dissipated in the bubble plume zone.
Linear contact algorithm for rigid‐plastic finite element simulation
Authors: Tekkaya Ahmet Erman , Şen Abdullah 
Published: December 2016

The rigid‐plastic finite element analysis of metal forming processes is known to be much more efficient and stable than the elastic‐plastic one. This efficiency results from the absence of kinematical nonlinearities in the formulation. Contact algorithms used in rigid‐plastic models must agree with this fact, otherwise the efficiency can be damaged seriously.The aim of this paper is to present a linear contact algorithm designed specially for rigid‐plastic analysis of metal forming problems. The linearization is achieved by dictating constancy of boundary conditions during one increment according to the requirement of the variational principle by Markov. The algorithm consists of two parts: the contact search and the contact control. The procedure has been implemented for two‐dimensional cases. However, the generalization to three dimensions is straightforward.The efficiency and the stability of the proposed procedure has been validated by means of examples of application such as extrusion and forging. Furthermore, parametric studies of the contact variables have been performed.
Hot model experiments of the metal bath spraying effect during the decarburization of Fe‐C melts through oxygen top blowing
Authors: Koch Klaus , Falkus Jan , Bruckhaus Ralf 
Published: December 2016

During recent years decarburization has been steadily gaining importance in converter steel metallurgy at the expense of refining reactions for other slag‐forming companion elements. Because decarburization is currently a low‐slag operation, the phase contact between gas and metal is critical. With the decrease in the amount of slag foam, more attention must be paid to the spraying of iron droplets during oxygen blowing.The experiments were carried out in a hot model reactor with a 50 kg capacity by oxygen top blowing upon Fe‐C melts. The resulting spray of iron droplets was collected with the help of a special droplet sampler in the blowing converter.In the metal droplets a pronounced enhanced decarburization was found in comparison to the metal bath. The amount of metal spray was determined with respect to the oxygen blowing pressure, nozzle diameter, and distance between the lance and bath. Depending on the reactor contents, a high circulation rate of the droplets could be observed. At low blowing rates, FeO‐slag is formed and sprayed along with the metal.
The use of thermal analysis techniques for the validation of phase transformation models
Authors: Bodin Andre , Marchal Piet D. 
Published: December 2016

In the study of the phase transformation of steel several methods can be used to obtain information about the behaviour of steel during heating and cooling. In this research several conventional methods, e.g. dilatometry, were studied together with an in‐situ thermal analysis method (ISTA). This method, which can be applied to any cooling curve, enables us to draw conclusions as to the transformation behaviour of the steel. Using a continuous annealing simulator (Casim) a range of cooling rates can be investigated with the resulting mechanical properties.It will be demonstrated that ISTA can be performed on the results of a variety of experimental techniques and therefore under very different experimental conditions. It is possible to investigate transformation behaviour and mechanical properties on a single test piece. Using the pressurized air cooling of the Casim proves to be a good compromise between the possibilities of determining the mechanical properties and flexibility in cooling conditions of the specimens.
Orientation dependent surface segregation of antimony on non‐oriented electrical steel sheet
Authors: Jenko Monika , Vodopivec Franc , Grabke Hans Jürgen , Viefhaus Helmut , Praček Borut , Lucas Manfred , Godec Matjaž 
Published: December 2016

The surface segregation of antimony was studied using AES on a 1.8% Si steel alloyed with different mass contents of Sb (0.052 and 0.1%). The dependency of surface segregation on grain orientation and on the presence of other solute atoms (S. P. C, Al. Si) were investigated under UHV conditions in the temperature range from 450 to 900 °C.The results lead to an explanation for the formation of a texture rich in (100)‐grains in Si steel caused by the presence of Sb. Also grain boundaries were analysed by AES after annealing at 850, 700 and 550 °C for different times. Since the grain boundary segregation was negligible one can conclude that the texture formation results from orientation dependent surface segregation of Sb causing differences in surface energies and stabilities of different grains.
Calculation of some parameters of polyhedron bulging process
Authors: Jianling Dong 
Published: December 2016

Single‐curvature polyhedron bulging technology for manufacturing spherical vessels is to build spherical vessels by assembling and welding sheet blanks of zero‐curvature and single‐curvature into a polyhedron, then gradually bulging the polyhedron into a spherical vessel. With the technology, heavy presses and large dies are not needed, so spherical vessels can be built at low cost. In order to make a polyhedron after being bulged satisfy given dimension requirements of the spherical vessel, it is necessary to calculate wall thickness and diameter of the polyhedron under bulging pressure.In this paper, wall thickness decrement and deflection of a point on a single‐curvature polyhedron during bulging are measured, it proves that the wall thickness decrement is much smaller than the deflection. Under the assumption that wall thickness of a polyhedron keeps constant during bulging, the constant‐area spheritaxis principle is put forward. With this principle, methods of calculating diameter, wall thickness of a polyhedron and pressure under which the polyhedron becomes a spherical vessel are got. Besides, other applications of the principle are also given.