1. |
Determination of the phase boundaries of the wustite solid solution within the context of reduction tests |
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Archiv für das Eisenhüttenwesen,
Volume 64,
Issue 6,
2016,
Page 279-285
Eberhard Schürmann,
Urban Janhsen,
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摘要:
Oxygen reduction measurements performed isothermally on Fe2O3with CO/CO2gas mixtures make it possible, in combination with a system of equations describing the homogeneous wustite phase FeOn, to describe also the boundaries of this solid solution mathematically. Compared with corresponding data determined by Giddings and Gordon on the basis of a literature evaluation, the boundaries of the wustite field are found to shift to a much lower reduction potential. The developed system of equations makes it possible to plot the curves of the same oxygen concentration in the homogeneous wustite phase field of the Bauer‐Glaessner diagram. When comparing the reduction equilibria of the left‐ and right‐hand wustite solid solution boundary with the appropriate literature data there is a good agreement particularly with the measurements of Darken and Gurry. Significantly lower oxygen concentrations are found in the FeO phase diagram, however, especially at high temperatures. New concentration data derived from the systems of equations are also given for the melt equilibria of the wustite phase, which lead to the assertion that the liquidus curves of magnetite, wustite and iron are also shifted to a lower oxygen concentration. The decomposition point of the wustite is found at 570°C, 49.5 %, CO'2and 23.2 % oxygen.
ISSN:0003-8962
DOI:10.1002/srin.199301023
出版商:Wiley
年代:2016
数据来源: WILEY
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2. |
On the numerical calculation and non‐dimensional representation of velocity fields in bubble‐stirred ladle systems |
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Archiv für das Eisenhüttenwesen,
Volume 64,
Issue 6,
2016,
Page 286-291
Dipak Mazumdar,
Roderick I. L. Guthrie,
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摘要:
The numerical simulation of axisymmetric gas stirred ladle systems has been considered and a mathematical model based on the dimensionless form of the turbulent Navier‐Stokes equations developed. Embodying a simplified turbulence model in the calculation procedure, it is demonstrated from the first principles that non‐dimensional velocity components at relatively low gas flow rates, follow identical distribution patterns at equivalent dimensionless bath depths and radii, provided values of the parametersL/RandQ/R2.5are similar for the various gas stirred systems being considered. The theoretical analysis has been substantiated through numerical experimentations and by considering a set of five independant experimental studies on liquid velocity measurements reported in the literature.
ISSN:0003-8962
DOI:10.1002/srin.199301024
出版商:Wiley
年代:2016
数据来源: WILEY
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3. |
Influence of sulfur and Mn/S ratio on the hot ductility of steels during continuous casting |
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Archiv für das Eisenhüttenwesen,
Volume 64,
Issue 6,
2016,
Page 292-299
Gonzalo Alvarez de Toledo,
Oscar Campo,
Enrique Lainez,
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摘要:
The influence of S and (Mn/S) on the crack susceptibility of continuous casting steels was studied. It is theoretically demonstrated that there is a critical value of the (Mn/S) ratio, (Mn/S)c, under which a high susceptibility to cracking, during casting or deformation of as‐cast material, is expected. The value of (Mn/S)cincreases as the S content of the steel decreases. Based on literature data and results from rolling continuous casting billets the following experimental equation has been found: (Mn/S)c= 1.345 · S−0.7934. A high similarity between this experimental equation and the theoretical one is achieved. A comparison between the equation found and previous expressions from literature was carried out. The MSC index as the ratio between the (Mn/S) ratio of a steel and the corresponding critical one was defined. The MSC index is a useful tool for the analysis of experimental results from literature.
ISSN:0003-8962
DOI:10.1002/srin.199301025
出版商:Wiley
年代:2016
数据来源: WILEY
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4. |
Theoretical modelling of an isokinetical steel feeding system for near‐net‐shape strip casting |
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Archiv für das Eisenhüttenwesen,
Volume 64,
Issue 6,
2016,
Page 300-306
Reinhard Scholz,
Rudolf Jeschar,
Thomas Matschullat,
Ulrich Urlau,
Wolfgang Reichelt,
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摘要:
During near‐net‐shape casting as considered here, liquid steel in thicknesses between 5 and 15 mm has to be put onto a cooled belt recirculating with speeds of 30 to 60 m/min. On the belt the liquid steel solidifies, before it can be subjected to one or two in‐line hot deformation steps.The requirement that the surface and the shape of the strips should already have the best possible structure upon being cast means that high demands are placed above all on the liquid steel feeding system. Especially the liquid metal should ideally be cast with the lowest possible turbulence and at a casting speed which is equal to the speed of the conveyor belt or cooled conveyor belt. In other words, the relative speed between the cast liquid and the cooled conveyor should become “zero” in order that the cast liquid can be more or less “laid” onto the cooled conveyor (known as isokinetic feeding).Different kinds of feeding liquid metals onto a circulating belt are reported with main emphasis on the theoretical modelling of the so‐called underpressure feeding systems.It is shown that, on the one hand, the casting speed can be regulated independently of the input mass flow rate into the tundish and, on the other hand, the liquid can be accumulated in the tundish or discharged from it at constant casting speed.
ISSN:0003-8962
DOI:10.1002/srin.199301026
出版商:Wiley
年代:2016
数据来源: WILEY
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5. |
Solidification modelling of microstructure in twin‐roller thin strip casting of stainless steels |
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Archiv für das Eisenhüttenwesen,
Volume 64,
Issue 6,
2016,
Page 307-312
Steffen Thiem,
Wolfgang Löser,
Manfred Jurisch,
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摘要:
The influence of process parameters on the dendritic microstructure of thin strips cast by the twin‐roll method is analyzed in the framework of a one‐dimensional solidification model and compared with experimental results. As a relevant characteristic the secondary dendrite arm spacing Λ2as a function of the distance x from the roll surface is investigated. The difference between the local dendrite arm spacing near the strip surface and the strip centre, respectively, increases with the strip thickness and only depends on the casting temperature to a small extent. An increase in the strip/roller heat transfer coefficient due to a rising casting velocity or possibly enhanced roll‐separating forces leads to a decrease in the dendrite arm spacing. The effect of a sudden decrease in heat transfer during the solidification process, on the Λ2(x) characteristics, e.g. by a local separation of the solidified shell from the roller surface, is discussed.
ISSN:0003-8962
DOI:10.1002/srin.199301027
出版商:Wiley
年代:2016
数据来源: WILEY
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6. |
On the formation of double zones of necking during hot tensile tests |
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Archiv für das Eisenhüttenwesen,
Volume 64,
Issue 6,
2016,
Page 313-316
Wlodzimierz J. Kaluba,
Laurent Cau,
Gerard Mesmacque,
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摘要:
The phenomenon of double necking during hot tensile tests is discussed in this work. The investigation was carried out on high‐carbon steel using a tensile testing machine equipped with an integral heating system. Tensile tests were performed in a large temperature range to obtain the mechanical characteristic of the material. Microstructure evolution was observed by light microscopy and hardness measurements to determine the position of double zones of necking. A significant increase in flow stress of as‐transformed austenite was found to be at the origin of the double necking behaviour.
ISSN:0003-8962
DOI:10.1002/srin.199301028
出版商:Wiley
年代:2016
数据来源: WILEY
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7. |
Hot corrosion of Fe‐Cr‐Ni‐AI‐Si alloys in molten carbonate |
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Archiv für das Eisenhüttenwesen,
Volume 64,
Issue 6,
2016,
Page 317-321
Wafaa Abd‐el‐Rahem Ghanem,
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摘要:
The change in weight of five newly developed steel alloys containing Fe, 10–11.3 % Cr, 15–18.27 % Ni, 4.98–5.76 % Mn, 4.18–5.52 % Al and 0.36–1.5 % Si together with Inconel 690 and stainless steel 304 has been investigated in Na2CO3+ K2CO3eutectic mixture at 800°C under atmospheric pressure and under isothermal and cyclic conditions. The scales formed were examined with optical and scanning electron microscopy and were analysed by energy dispersive X‐ray diffraction techniques. It has been shown that the corrosion resistance of the alloys is far better than that of stainless steel 304, but slightly less than that of Inconel 690. The relatively high contents of Si and Al gave alloy 5 its highest corrosion resistance. About 0.2 % N were found to refine the grains without the danger of depleting the grain boundaries from Al and Cr. The results have been explained in the light of the alkaline conditions prevailing in the carbonate melt.
ISSN:0003-8962
DOI:10.1002/srin.199301029
出版商:Wiley
年代:2016
数据来源: WILEY
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8. |
Creep rupture and creep behaviour of martensitic X 18 CrMoVNb 11.1 type steel at elevated temperatures and after a temperature transient |
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Archiv für das Eisenhüttenwesen,
Volume 64,
Issue 6,
2016,
Page 322-330
Manfred Schirra,
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摘要:
Martensitic CrMoVNb 1.4914 type steel, which is at present being tested as a material for fuel element wrapper tubes, was subjected to tests in order to find out the impact on the original hardening and tempering strength of brief temperature rises up to 975°C.T‐transients in the range between 800 and 900°C (20–36 min>Ac1b) do not exert a pronounced influence on creep‐rupture strength; merely the times up to ≤ 1 % creep strain are clearly reduced, as is indicated by creep‐rupture tests at 650°C. There is a more pronounced influence on creep rupture and creep behaviour if the transient extends into the 975°C region and is subsequently held in the range of 600–750°C, where transformation to the pearlite stage occurs. High creep stability is seen at holding temperatures of400°C. The explanation is furnished by the findings obtained in isothermal creep‐rupture tests aboveAc1b(800–925°C). Extensive metallographic examination confirms the structural changes expected from the IT‐diagram.
ISSN:0003-8962
DOI:10.1002/srin.199301030
出版商:Wiley
年代:2016
数据来源: WILEY
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