1. |
Experimental studies on the bath oscillation during gas blowing into liquids, part 2: measurements in a converter model |
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Archiv für das Eisenhüttenwesen,
Volume 63,
Issue 7,
2016,
Page 277-280
Yongkun Xie,
Franz Oeters,
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摘要:
Experimental studies on the wave motion during gas blowing into liquid iron in a converter model were carried out on the systems water/air and Wood's alloy/nitrogen under various blowing conditions. Variables of the measurement were the gas flow rate and the configuration of nozzles. The measured results showed that a wave motion appears only if the gas flow rate exceeds a critical value which depends on the nozzle configuration. The blowing conditions for wave formation can be characterized by the relation of the bath depth to the vessel diameter and by the gas flow rate. The frequency or the oscillation period of the wave is independent of the gas flow rate. The amplitude of the wave follows a logarithmic function of gas flow rate.
ISSN:0003-8962
DOI:10.1002/srin.199200517
出版商:Wiley
年代:2016
数据来源: WILEY
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2. |
Carbon utilization in direct smelting systems |
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Archiv für das Eisenhüttenwesen,
Volume 63,
Issue 7,
2016,
Page 281-290
Amit Ganguly,
Ken J. Reid,
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摘要:
Carbon is used in smelting systems for the two primary functions of reduction and heat generation. Depending on the nature of the smelting device, a variety of methods of introducing the carbon result. There is also a wide choice of carbon‐bearing raw materials with current emphasis on the utilization of coal. This paper analysis the underlying mechanisms for coal pyrolysis and char dissolution as they relate to the emerging in‐bath smelting systems. The influence of coal quality on process performance is discussed based on reported work in both the bench scale and pilot‐scale levels.
ISSN:0003-8962
DOI:10.1002/srin.199200518
出版商:Wiley
年代:2016
数据来源: WILEY
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3. |
Reanalysis of solidification behaviour from the microstructure in near‐net‐shape casting of steels |
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Archiv für das Eisenhüttenwesen,
Volume 63,
Issue 7,
2016,
Page 291-296
Steffen Thiem,
Wolfgang Löser,
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摘要:
Numerical calculations revealing the relationship between the as‐cast structure and cooling conditions in near‐net‐shape casting of steels are presented. The solidification behaviour of steels of different composition was investigated for different process conditions with a one‐dimensional heat‐flow model. The dependence of the secondary dendrite arm spacing (SDAS) on the distance from the chill surface was determined on the basis of the empirical relationship between local solidification time and SDAS. The numerical results were compared with experimental values of SDAS for a stainless steel, a carbon tool steel and a high‐speed steel, resp. Reasonable agreement of model calculations with the experimentally determined SDAS was obtained utilizing time‐dependent effective heat‐transfer coefficients of the order of 2.5 to 4.5 · 103W/m2K for typical thin‐slab dimensions and 6.0 · 103W/m2K for thin‐strip casting.
ISSN:0003-8962
DOI:10.1002/srin.199200519
出版商:Wiley
年代:2016
数据来源: WILEY
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4. |
Hot‐rolling simulation and modelling using Gleeble 1500 |
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Archiv für das Eisenhüttenwesen,
Volume 63,
Issue 7,
2016,
Page 297-303
Reuben Austin Morgridge,
Pentti Karjalainen,
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摘要:
Using the Gleeble 1500, incremental and continuous hot compression tests, simulating hot rolling, were performed on C‐Mn, Nb‐T, and Nb steels with test temperatures varying between 875 and 1100°C and strain rates between 0.5 and 20 s−1. Four models are proposed. The stress peak model allows the prediction of continuous stress‐strain curves from incremental curves and vice versa through the use of stress restoration indexK. Variation inKfor Nb‐T1, C‐Mn and Nb steels at strain rates of 3, 12 and 20 s−1was found to be negligible. The predicted stress strain curve corresponds to experimental stress strain curve at same temperature and strain rate. The strain history model predicts continuous strain‐time curves from incremental stress‐strain curves using ‘constant’ ‘negative strain’ restoration index. At 950°C, with holding time 2 s and strain rate 12 s−1, strain time decay curves obtained for C‐Mn, Nb and Nb‐T, steels were ε = 1.5e−05t, ε = 1.2e−0.36tand ε = e−0.3t, respectively. The creep model analysis relates creep strain rate to the testing strain rate. For Nb steel at 875°C, and test strain rate of 12 s−1, ∊creepwas found to be 9.5 s−1. The stress history model predicts continuous stress‐time curves from incremental stress‐time curves. Stress decay curve for C‐Mn steel at 1100°C and ∊ = 3s−1was found to be σ = 181e−0.04t. Hot rolling characteristics of steels can be accurately predicted using hot compression tests and proposed models.
ISSN:0003-8962
DOI:10.1002/srin.199200520
出版商:Wiley
年代:2016
数据来源: WILEY
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5. |
Evaluation of friction under hot working conditions in a high temperature test rig |
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Archiv für das Eisenhüttenwesen,
Volume 63,
Issue 7,
2016,
Page 304-308
Sven‐Erik Lundberg,
Bertil Waldén,
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摘要:
A new high temperature test rig was designed and constructed. In a first series of tests it was shown that by proper choice of testing parameters, wear mechanisms similar to those in rolls in operation could be achieved. By comparison of frictional values evaluated from experiments in the test rig to values evaluated from ring upsetting tests, an attempt is made to establish the high temperature test rig experiments as a method for simulation of the tribological situation in hot rolling. The coefficient of friction μ was evaluated and fairly good agreement was found with frictional values from ring upsetting tests. However, it is doubtful whether μ is a relevant measure of friction in hot working processes, and in the ring upsetting tests also the friction factormwas evaluated. Evaluation ofm‐values from the test rig experiments might be possible. However, such an evaluation claims both a correct shear yield stress value of the hot material and a relevant description of the contact surface area. Since no plastic deformation occurs in the test rig a “semi‐plastic” state must be established and verified. Different attempts can seem realistic, but it is obvious that the evaluation ofm, using a “semi‐plastic” state can be manipulated by the choice of conditions by calculating the shear yield stress. Furthermore, it is not clarified whether the Hertzian theory of elastic contacts is valid for a temperature of 1000°C. Thusm‐values evaluated from the test rig have no meaning and the frictional conditions must be characterized by the coefficient of friction μ.Since both relevant frictional and wear conditions are obtained, the high temperature test rig can be used for simulation of roll wear and for the development of new, more wear resistant roll grades.
ISSN:0003-8962
DOI:10.1002/srin.199200521
出版商:Wiley
年代:2016
数据来源: WILEY
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6. |
Anwendung eines Simulationsmodells zur Berechnung der Blechprofile beim Kaltwalzen breiter Bleche auf einem Sendzimir‐Sexto‐Walzgerüst |
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Archiv für das Eisenhüttenwesen,
Volume 63,
Issue 7,
2016,
Page 309-314
Paul Funke,
Michael Eckhardt,
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摘要:
Zur Überprüfung und Ergänzung eines Modells zur Simulation von Walzungen auf einem Sendzimir‐Sexto‐Walzwerk wurden Rechnungen durchgeführt. Deren Ergebnisse wurden mit Daten aus Betriebsmessungen verglichen. Die gute Übereinstimmung zwischen berechneten und gemessenen Werten bestätigt die Anwendbarkeit des Modells. In weiteren Rechnungen wird deutlich, daß mit diesem Gerüst eine Walzwerkskonzeption zur Verfügung steht, die insbesondere bei großen Blechbreiten die Erzeugung planen Walzgutes ermöglicht. Mit abnehmender Blechbreite wird jedoch auch hier die Beherrschung der Planlage schwieriger; die in den einzelnen Stichen erzielbaren Dickenabnahmen werden durch die Anforderungen an die Blechplanheit begrenzt. Eine höhere Ausnutzung der zulässigen Walzkräfte kann durch eine Vergrößerung des Stellbereiches der Stützwalzenbombierung und/oder durch eine Änderung des Arbeitswalzenschliffes erreicht werden.
ISSN:0003-8962
DOI:10.1002/srin.199200522
出版商:Wiley
年代:2016
数据来源: WILEY
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7. |
ECSC announcements |
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Archiv für das Eisenhüttenwesen,
Volume 63,
Issue 7,
2016,
Page 314-314
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ISSN:0003-8962
DOI:10.1002/srin.199200523
出版商:Wiley
年代:2016
数据来源: WILEY
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8. |
Some fundamental questions about R‐curves |
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Archiv für das Eisenhüttenwesen,
Volume 63,
Issue 7,
2016,
Page 315-317
Otmar Kolednik,
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摘要:
With the help of two simple thought experiments it is demonstrated that there exist two physically different types of fracture toughness. The crack‐growth toughness, which is identical to the Griffith crack growth resistance,R, is a measure of the non‐reversible energy which is needed to produce an increment of new crack area. The size ofRis reflected by the slopes of theR‐curves commonly used. So an increasingJ‐Δa‐curve does not mean that the crack‐growth resistance increases. The fracture initiation toughness,Ji, is a normalized total energy (related to the ligament area) which must be put into the specimen up to fracture initiation. Only for ideally brittle materialsRandJihave equal sizes. For small‐scale yielding a relationship exists betweenRandJi, so a one‐parameter description of fracture processes is applicable. For large‐scale yieldingRandJiare not strictly related and both parameters are necessary to describe the fracture process.
ISSN:0003-8962
DOI:10.1002/srin.199200524
出版商:Wiley
年代:2016
数据来源: WILEY
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9. |
News from the Max‐Planck‐Institut für Eisenforschung GmbH |
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Archiv für das Eisenhüttenwesen,
Volume 63,
Issue 7,
2016,
Page 318-318
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ISSN:0003-8962
DOI:10.1002/srin.199200525
出版商:Wiley
年代:2016
数据来源: WILEY
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