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The Institute für Allgemeine Metallurgie at the Technical University Clausthal |
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Archiv für das Eisenhüttenwesen,
Volume 63,
Issue 11,
2016,
Page 473-482
Karl‐Heinz Spitzer,
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ISSN:0003-8962
DOI:10.1002/srin.199201745
出版商:Wiley
年代:2016
数据来源: WILEY
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Development of a reduction process and test results of the reduction equilibria of wustite as a function of oxygen content and temperature |
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Archiv für das Eisenhüttenwesen,
Volume 63,
Issue 11,
2016,
Page 483-492
Eberhard Schürmann,
Urban Janhsen,
Erhard Beppler,
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摘要:
A new measurement technique allows the continuous measurement of the oxygen contents of the wustite as a function of temperature without having to pass through the disintegration of the wustite to iron and magnetite and have the accompanying problems during the chemical analysis by cooling the sample. Measurements are carried out in form of isothermal oxygen reduction tests, starting with pure Fe2O3in a thermogravimetric balance with an upstream gas mixer which, operating with CO2/CO gas mixtures, ensures a graduation of the input reduction potential CO'2in steps of 1%. Simultaneous weighing of the test material sample permits, by means of the measured weight loss and relation to the charged amount of Fe2O3, a very accurate measurement of the oxygen concentration within the test material at any point in time during testing. Testing was carried out along these lines in the range between 700 and 1300°C. The results show that, at constant temperatures, the wustite oxygen contents decrease linearly from the right‐ to the left‐hand boundary of the wustite field, with the oxygen pressure of the gas phase (logpCO2/pCOor logpO2). When comparing these results with the findings of Darken and Gurry, a difference becomes apparent in the curves of the logpO2values as a function of the temperature. While our own curves are substantiated by very many measured values, the curves of Darken and Gurry are based on only twenty‐three values at four different temperatures. Based on this result, systems of equations are developed which describe the homogeneous field of the wustite in the Fe‐O‐C reduction system without any gaps. An equivalent system of equations can also be developed from the values of a literature evaluation carried out by Giddings and Gordon. The curves resulting from the two equations do not differ very greatly. But the differences are large enough for corresponding variances to be expected when establishing the wustite boundaries and, thus, the position of the wustite field in the phase diagram.
ISSN:0003-8962
DOI:10.1002/srin.199201746
出版商:Wiley
年代:2016
数据来源: WILEY
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Study of the oxidation protection of MgO‐C refractories by means of boron carbide |
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Archiv für das Eisenhüttenwesen,
Volume 63,
Issue 11,
2016,
Page 493-495
Tadeusz Rymon‐Lipinski,
Ralf Fichtner,
Theodor Benecke,
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摘要:
Boron carbide is used as a highly effective antioxidant in carbon‐containing refractories. The oxidation‐inhibiting action of this additive has not been clearly defined. The work first deals in theory with the stability of boron carbide at high temperatures. The practical section presents the reaction sequence as determined by means of thermogravimetric analysis and X‐ray diffraction analysis. The tests showed that B4C oxidizes during firing at below 1000°C, to give magnesium borate (3 MgO · B2O3), which is stable at high temperatures.
ISSN:0003-8962
DOI:10.1002/srin.199201747
出版商:Wiley
年代:2016
数据来源: WILEY
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4. |
A parametric study of the accelerated cooling of steel strip |
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Archiv für das Eisenhüttenwesen,
Volume 63,
Issue 11,
2016,
Page 496-499
J. Filipovic,
Raymond Viskanta,
F. P. Incropera,
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摘要:
To gain insight into the effects of various parameters controlling the thermal behaviour of a quenched steel strip during the process of accelerated cooling by an array of planar water jets, a parametric study has been performed using a previously developed and validated mathematical model. The behaviour of the strip was characterized by its coiling temperature, top and bottom surface temperature variations and heat extraction in the jet impingement region, top surface heat extraction in the film boiling region, and top and bottom surface thermal penetration depths. Parametric variations included cooling system design conditions, such as the top and bottom nozzle widths, and operating conditions such as the top nozzle discharge velocity, the cooling water temperature, and the ratio of volumetric water flow rates applied at the top and bottom surfaces. The effects of steel strip parameters such as strip thickness and strip velocity were also considered.
ISSN:0003-8962
DOI:10.1002/srin.199201748
出版商:Wiley
年代:2016
数据来源: WILEY
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Retained austenite in the cracking process of steel on the working rolls of the cold sheet rolling mill |
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Archiv für das Eisenhüttenwesen,
Volume 63,
Issue 11,
2016,
Page 500-503
Jerzy Pacyna,
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摘要:
It was proved that the volume fraction of retained austenite (RA) in the quenched samples of the 0.80%C, 1.80%Cr, 0.23%Mo, 0.17%V steel on the working rolls of cold sheet rolling mills depends on their sizes. During tempering of this steel at 160°C the RA is stabilized so strongly that it is transformed neither by means of stresses nor strains. It was computed that in this steel, every 1% by volume of RA increases its fracture toughness (Klc) by about 5%. Under conditions of dynamic loading the power of effect of RA is increased to about 7%.
ISSN:0003-8962
DOI:10.1002/srin.199201749
出版商:Wiley
年代:2016
数据来源: WILEY
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Possibilities of influencing the γ‐α‐transformation products of hot‐rolled pearlitic steels |
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Archiv für das Eisenhüttenwesen,
Volume 63,
Issue 11,
2016,
Page 504-511
Cestmir Lang,
Radko Kaspar,
Manfred Koschlig,
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摘要:
Controlled alloying, optimum configuration of the rolling schedules, and a suitable cooling strategy make it possible to broadly influence the microstructure and mechanical properties of higher‐carbon steels. Increasing the manganese content and microalloying with vanadium delay the diffusion‐controlled γ‐α‐transformation, and the increase in the amount of pearlite improves strength properties. Lowering of the finishing temperature refines the austenite microstructure, and increases the level of residual strengthening that remains in the austenite. This changes the amount of ferrite and improves the resistance to brittle fracture. Applying a cooling interruption step in the ferrite formation temperature range also permits an additional variation of the amount of ferrite. The extent to which recalescence develops during the formation of pearlite can bring about significant changes in the pearlite morphology and hence influence strength and toughness properties. Accelerated cooling to a low coiling temperature, as a further process‐related modification, promotes the formation of bainite, obtaining high strength properties without any mentionable loss of toughness.
ISSN:0003-8962
DOI:10.1002/srin.199201750
出版商:Wiley
年代:2016
数据来源: WILEY
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Strengthening and toughening treatment of steel used as the material of multistation progressive dies |
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Archiv für das Eisenhüttenwesen,
Volume 63,
Issue 11,
2016,
Page 512-514
Yuan‐qi Tang,
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摘要:
The Cr12MoV steel was chosen as the material of multistation progressive dies, and its impact toughness and hardness were measured, following different heat treatments. Based on experimental results, a practical technology carried out in vacuum is recommended as the strengthening and toughening treatment for these dies: 980°C oil pre‐quenching, oil quenching again at 980°C, final tempering at 200°C for 1 hour, and then air cooling. This treatment makes the steel have fine austenitic grains and carbide particles, and thus leads to good combination of strength and toughness such that the service life of the dies is increased.
ISSN:0003-8962
DOI:10.1002/srin.199201751
出版商:Wiley
年代:2016
数据来源: WILEY
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