1. |
Classification of blast furnace probe temperatures using neural networks |
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Archiv für das Eisenhüttenwesen,
Volume 66,
Issue 6,
2016,
Page 231-236
Abhay Bulsari,
Henrik Saxén,
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摘要:
Classification of spatially distributed measurements in industrial processes is often a difficult task. A typical example is given by the interpretation of the gas temperatures from horizontal probes in blast furnaces. This paper presents a neural network‐based classification of temperature measurements from an above‐burden probe. An expert on blast furnace supervision and control first classified a large set of temperature profiles into six different stereotype patterns. Roughly 40 % of this material was used for training feedforward neural networks, while the remaining profiles were used for evaluation of the networks' performance in order to determine an appropriate network size. In general, consensus was found among the networks in that similar erroneous or inconsistent classifications made by the human expert were detected. However, the network size clearly affected the quality of the classifications. The work demonstrated the merits of a rapid, consistent, and automatic (neural) interpretation, as well as the risk of misclassification and the subjectivity involved when human experts have to evaluate complex patterns.
ISSN:0003-8962
DOI:10.1002/srin.199501117
出版商:Wiley
年代:2016
数据来源: WILEY
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2. |
Aluminum deoxidation equilibrium in liquid Ni‐Fe alloys equilibrated with CaO‐Al2O3slags |
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Archiv für das Eisenhüttenwesen,
Volume 66,
Issue 6,
2016,
Page 237-243
Sung‐Wook Cho,
Hideaki Suito,
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摘要:
The deoxidation equilibrium for Al in Ni‐Fe alloys was studied in the equilibrium experiments between CaO‐Al2O3slags and Fe‐30, 50 and 70 % Ni alloys at 1873 K. By using the values for the first and second order interaction parameters between oxygen and nickel in liquid iron and those between oxygen and iron in liquid nickel, the effect of Ni on the activity coefficient of Al in liquid iron and that of Fe on the activity coefficient of Al in liquid nickel were determined in the whole composition range of Ni‐Fe alloys. The oxygen contents in Ni‐Fe alloys calculated by the iterative method based on pure iron were in good agreement with those based on pure nickel in the range of [% Al]<0.03. From this fact, it was found that the Wagner's approximation relating to the multi‐component solution was applicable to the deoxidation equilibrium in the whole composition range of Ni‐Fe alloys in the restricted concentration of a deoxidizer.
ISSN:0003-8962
DOI:10.1002/srin.199501118
出版商:Wiley
年代:2016
数据来源: WILEY
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3. |
A new, optical measuring technique for the determination of the vapour film thickness during film boiling |
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Archiv für das Eisenhüttenwesen,
Volume 66,
Issue 6,
2016,
Page 244-250
Reiner Weichert,
Rudolf Jeschar,
Walter Klemm,
Viktor Heidt,
Patrick Thibor,
Heike Mühlenweg,
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摘要:
A non‐contact measuring technique was developed and tested to determine the thickness of a vapour film during film boiling. The technique is based on the different optical properties of vapour and water admixed with a fluorescent substance. Pictures were taken of the surroundings of the vapour film using a long‐distance microscope of high resolving power and a TV‐camera; they were recorded with a video recorder. The pictures were evaluated using methods of digital image processing and by application of a model for the intensity distribution of fluorescence‐radiation. The technique was tested on a steel sphere heated to 690°C and subsequently immersed into warm water of 55°C. The thickness of the vapour film directly after immersion was determined at 0.20 mm. The thickness decreased continuously during the cooling process and reached a thickness of 0.11 mm after 20 s, immediately before the collapse of the vapour film. The surface temperature of the steel sphere immediately before the collapse was about 420°C. The thicknesses of the vapour film calculated with a simple theoretical model were found to be about 50 % smaller than those measured.
ISSN:0003-8962
DOI:10.1002/srin.199501119
出版商:Wiley
年代:2016
数据来源: WILEY
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4. |
Microstructure and mechanical properties of rapidly solidified Fe‐25%Cr‐5%Al ribbons produced by planar flow casting |
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Archiv für das Eisenhüttenwesen,
Volume 66,
Issue 6,
2016,
Page 251-253
José A. Jiménez,
Wolfgang Frech,
Oscar A. Ruano,
Georg Frommeyer,
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摘要:
Catalyst substrate foils of the highly oxidation resistant Fe‐25Cr‐5Al alloy (mass contents in %) with a thickness ranging from 40 to 180 μm have been produced by planar flow casting. The rapidly solidified ribbons showed a monophase ferritic microstructure of columnar grains. The grain size determined over a section parallel to the ribbon wheel side ranged from 5 μm for the thin ribbons (40 μm) to 18 μm for the thicker ones {180 μm). This anisotropic columnar solidification microstructure exhibits a strongfiber texture, with the fiber axis nearly perpendicular to the plane of the ribbon. The position of the maximum in the pole figure was tilted from the center point toward the casting direction. Results of uniaxial tensile tests showed that only the yield stress data of the ribbons in the as‐cast condition are reproducible, whereas the ultimate tensile strength and the elongation to failure data show a wide scatter band. The fracture mode exhibits ductile features such as glide bands and dimples.
ISSN:0003-8962
DOI:10.1002/srin.199501120
出版商:Wiley
年代:2016
数据来源: WILEY
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5. |
Effect of sulfur on the stability of cementite |
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Archiv für das Eisenhüttenwesen,
Volume 66,
Issue 6,
2016,
Page 254-258
Hans Jürgen Grabke,
Else Marie Müller‐Lorenz,
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摘要:
Cementite Fe3C is an unstable carbide, which should decompose to iron and graphite. It was possible to grow cementite on iron samples in flowing CO‐H2‐H2O‐H2S mixtures at temperatures between 400–700°C. The cementite is stabilized by adsorbed sulfur, preventing graphite deposition, which would initiate metal dusting. Thus, this corrosion phenomenon, occurring in CO‐H2‐H2O and other strongly carburizing atmospheres can be suppressed by the presence of some H2S. The range of H2S/H2ratios and temperatures in which iron is inert against metal dusting, corresponds to the range where a monolayer of sulfur is adsorbed in iron. It may be supposed that the iron carbide process, i.e. the production of Fe3C by reduction of ores in methane, is possible only by the presence of some sulfur.
ISSN:0003-8962
DOI:10.1002/srin.199501121
出版商:Wiley
年代:2016
数据来源: WILEY
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6. |
Temperature dependence of the microscopic cleavage fracture stress |
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Archiv für das Eisenhüttenwesen,
Volume 66,
Issue 6,
2016,
Page 259-263
Christoph Jüde‐Esser,
Fabian Grimpe,
Winfried Dahl,
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摘要:
The microscopic cleavage fracture stresswhich could be responsible for dramatic failure is commonly seen as a temperature independent material property. But a dependence on temperature was found in several former investigations. In this work new studies on cleavage fracture with low carbon steel C 10 were performed. The stresswas determined with double‐edge notched tensile (DENT) specimens at different temperatures and various crosshead speeds. In addition tests were made with four‐point bend specimens (SENB4) according to Griffiths and Owen. A significant influence of temperature on the microscopic cleavage fracture stress was found. The explanation for this result is seen in terms of the thermal activation of dislocation movement, which is needed to produce the critical conditions for fracture. As temperature independence is proposed from the “Local Approach” a check up of this procedure is given and limitations of the “Weakest Link‐model” are shown.
ISSN:0003-8962
DOI:10.1002/srin.199501122
出版商:Wiley
年代:2016
数据来源: WILEY
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7. |
The influence of tempering on cleavage fracture stress and transition behaviour of bainitic 2.25Cr1Mo steel |
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Archiv für das Eisenhüttenwesen,
Volume 66,
Issue 6,
2016,
Page 264-271
Miloslav Holzmann,
Bohumil Vlach,
Jiří Man,
Jan Krejčí,
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摘要:
The effect of tempering on the mechanical properties and on the cleavage fracture stress of bainitic 2.25Cr1Mo steel was studied in a variety of structures with the Hollomon‐Jaffe parameterMranging between 18.23 × 103and 21.70 × 103. The rapid decrease in yield stress and UTS was observed up to valueM= 20 × 103. For valuesM>20 × 103the reduction of yield stress and UTS slows down. The cleavage fracture stress continuously decreases with increasing value ofM. Concurrently, the changes in dislocation density and in carbide size, morphology and distribution were observed. Various theories of cleavage origin of tempered bainitic microstructures are discussed. The transition temperatures, determined from impact Charpy test, reach minimum atM= 20 × 103. Using Orowan's theory of initiation of the brittle fracture in steels, the minimum of transition temperatures may be explained by the different reduction rates of cleavage fracture stress and yield stress with value ofM.
ISSN:0003-8962
DOI:10.1002/srin.199501123
出版商:Wiley
年代:2016
数据来源: WILEY
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8. |
Component specific influences on the fracture behaviour of high speed steels under static loading |
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Archiv für das Eisenhüttenwesen,
Volume 66,
Issue 6,
2016,
Page 272-277
Nils Lippmann,
Heinz‐Joachim Spies,
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摘要:
This paper presents the first results of a series of investigations into the fracture behaviour of high speed steels with regard to component specific influences. The aim of the investigations was the analysis of the interaction of internal and external notches during the fracture process. Hardened and tempered high speed steel S 6‐5‐2 of various degrees of hot forming, which was produced by electroslag remelting, as well as powder‐metallurgically produced high speed steel ASP 23 were tested to investigate the influence of different carbide sizes and distribution.In‐situ bend tests showed the role of the carbides as fracture initiating defects, which form subcritical cracks as a result of the higher stiffness and lower failure stress at loads smaller than the global failure load of the specimen. The observed fracture process was simulated by FEM using the observations and results of the in‐situ bend tests.The interaction of internal flaws and external notches was proven using notched and coated specimens as well as specimens of various surface roughness. The fracture initiating defect is the largest defect in the loaded volume regardless of whether it is an internal flaw (carbide) or an external notch (surface roughness, surface layer). Information can be derived from the investigations allowing the optimisation of the manufacture of high speed steel tools with regard to their fracture behaviour.
ISSN:0003-8962
DOI:10.1002/srin.199501124
出版商:Wiley
年代:2016
数据来源: WILEY
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