bluuebunny/crossref_metadata_2025 huggingface dataset:
A simple probabilistic approach to the derivation of minimum yield strength values of steels at elevated temperatures
Authors: Rohde Walter
Published: December 2016

For the derivation of minimum yield strength values of steels at elevated temperatures, the formula Rp0.2/T/min = Rp0.2/20/min (1.1·fav/T − 0.1) is proposed, where fav/T is the interpolated average trend value at a specified temperature, obtained by polynomial interpolation of the individual ratio values fT = Rp0.2/T/Rp0.2/20 at all the test temperatures. The values of fav/T characterize the trend of the Rp0.2‐mean value line in function of the temperature. They are dependent on the material and on the temperature. The factor 1.1 and the reduction value 0.1 are interpreted in terms of a simple probability model. The model is based on the assumption that the total scatter of the test results is composed of two parts. One of these two parts is the correlation induced scatter due to the correlation between Rp0.2/T− and Rp0.2/20‐values. The other one is the residual scatter. By evaluation of a number of data groups it is demonstrated that, for engineering purposes, the standard deviation of the residual scatter may be taken as about 5% of Rp0.2/20/min independent of the temperature. The validity of the formula is confirmed for ferritic and austenitic steels with minimum yield strength values at room temperature between 200 and 800 MPa and for fav/T‐values between 1 and 0.3. The connections with the ISO‐method set down in ENV 22605‐1 and ENV 22605‐2, with the trend curve method set down in ENV 22605‐3 and with the recently proposed modified trend curve method are explained.
Characterization of laser‐beam surface treated cold and hot working steels
Authors: Kron Petra Britt , Dahl Winfried , Bleck Wolfgang
Published: December 2016

In order to increase the wear resistance of metal forming tools, four different cold and hot working steels were laser‐beam surface melted and alloyed with titanium carbide and vanadium carbide. The layers were investigated concerning chemical composition, microstructure, hardness profiles, wear behaviour measured by pin‐on‐disk‐tests with different counterbodies and plastic behaviour of the surface by a new developed repeated impact testing machine. It turned out to be more useful to take a substrate which is already quenched and tempered prior to the laser‐beam surface treatment than to carry out the tool hardening heat treatment afterwards. A tempering step after the laser‐beam alloying offers the advantage of carbide precipitates in the layer connected with an increase in the hardness and a reduction of residual stresses. By means of laser‐beam surface alloying the wear protection of the layer can be increased while the alloying content of the substrate is reduced with respect to the core fracture toughness. The optimal alloying addition depends on the demands of the envisaged application.
Polythermal description of the oxygen pressures in the melts of the Subsystems Fe‐FeOn and FeO‐Fe2O3
Authors: Schürmann Eberhard , Rasim Wolfgang , Heimann Klaus
Published: December 2016

The phase equilibria in the Subsystem Fe‐FeO of the Compound System FeO ranging from mole fractions of xo = 0 to xo = 52% are characterised by a wide miscibility gap. Using the van Laar formulation, it is possible, up to mole fractions of xo = 51%, to describe the liquidus line of the iron, the phase boundaries of the miscibility gap and, with the resultant activities aFe and aFeOn, the oxygen pressures of the liquid phases either side of the miscibility gap, in a manner consistent with the temperature‐dependent, experimental data of the relevant literature. In the overlap range (oxygen mole fractions of 50 − 52%) to the adjacent Subsystem FeO‐Fe2O3 (oxygen mole fractions of 50 − 60), a continuous transition is achieved to the experimentally ascertained oxygen pressures in the liquid oxide melts, these being characterised by a tendency towards Compound formation. These ‐values are very accurately described polythermally by the modified short‐range‐order model with stipulation of the short ranges 3FeO·Fe2O3 and FeO·Fe2O3, and also of the dissociation reaction 3(FeO) = (Fe2O3) + [Fe] and (Fe2O3) = 2(FeO) + [O].
Microstructural stability of the martensitic steel X20CrMoV12‐1 after 130000 h of service at 530°C
Authors: Straub Stefan , Blum Wolfgang , Röttger Dietmar , Polcik Peter , Eifler Dietmar , Borbély András , Ungár Tamás
Published: December 2016

The microstructural changes in a tube section of X20CrMoV12‐1 due to service are investigated. The investigation was carried out by combining mechanical tests, finite element calculations and mainly quantitative characterisation of the microstructure by electron microscopy.

The tensile and fatigue tests at room temperature did not show differences between the tube section and the initial State of another melt. At the approximate service temperature the deformation resistance of the service exposed material is slightly lower. The finite element calculations indicate no plastic deformation. The quantitative characterisation of the microstructure shows that the dislocation structure does not differ from the initial State of other melts. On the other hand the carbide structure grows with time at temperatures prevailing during service. The coarsening of the carbide structure may be the reason for a lower high temperature deformation resistance of the material of the tube section. The microstructural results indicate that the tube section was not influenced by plastic deformation during service.
The precipitation diagram of [Ce]‐[O]‐[S] in liquid iron and its application
Authors: Dong Yuanchi , Han Qiyong
Published: December 2016

A space precipitation diagram of [Ce]‐[O]‐[S] in pure liquid iron has been constructed utilising recent experimental thermodynamic data gathered on allied equilibrium systems of RE‐O, RE‐S and RE‐O‐S. A quantitative correlation between the activities of oxygen, sulphur and the constitution of the formed RE inclusions has been found. This correlation was theoretically evaluated through thermodynamic calculation and verified by experimental data concerned with the activities of oxygen and sulphur in liquid iron and the composition of the formed RE inclusions.
Denitrogenation of steel melts with oxygen and sulphur by injection of argon under reduced pressure
Authors: Thoms Andreas , Tu Shiwei , Janke Dieter
Published: December 2016

Denitrogenation of steel melts with oxygen and sulphur was studied under reduced pressure by injection of argon. The rate of nitrogen desorption was found to obey a reaction of second order. The macrokinetic rate increases with increasing Ar flowrate until bubble coalescence occurs in the melts. The effects of sulphur and oxygen on nitrogen desorption were evaluated from the experimental data.

The dimensionless rate constant for nitrogen is described by . A reasonable agreement was obtained in comparison with the results of other investigators.
Interrelation between kinetics of reduction and volume change during formation of directly reduced iron rod
Authors: Goswami Manik C.
Published: December 2016

A kinetic study on reduction has been carried out by heating a central column of blue dust (a fine variety of iron ore) surrounded by a concentric layer of non‐coking coal fines in the temperature range of 1173‐ 1323 K. The temperature of the periphery of blue dust column is kept constant at the temperature of experimentation, however, the temperature of the interior of the cylindrical column increases with time of residence and the change in volume of the reaction mass occurs. The loose column of blue dust gets reduced, consolidated and sintered to produce directly reduced iron rod (DRIR). The work also comprises studies concerning the effect of volume change on the reduction kinetics. The reduction phenomena are very much influenced by the change in volume of reaction mass. The kinetics of reduction shows an agreement with Ginstling‐Brounshtein model whereas the kinetics of change in volume is interpreted using Johnson‐Mehl equation. The rate constants k1 and k2 derived from kinetic analysis of reduction and volume change respectively are shown to be linearly interrelated till the change in volume with respect to the original volume becomes more or less constant.
Liquid equilibria in the Fe–Ni–Mn system
Authors: Schürmann Eberhard , Djurdjevic Mile , Nedeljkovic Ljubomir
Published: December 2016

New literature results on the liquid equilibria in the three edge binary systems make necessary a reconsideration and correction of liquidus surfaces of the γ and δ solid solutions hitherto outlined in the literature. Therefore, with respect to the critically reinterpreted edge binary systems, the shape of the stable liquidus surface of the γ and δ solid solutions has been newly outlined.
Application of thermomechanical treatment on medium‐carbon microalloyed steels continuously cooled from forging temperature
Authors: Kaspar Radko , González‐Baquet Ignacio , Schreiber Nadja , Richter Johannes , Nußbaum Georg , Köthe Alfred
Published: December 2016

In the high‐production‐drop‐forging of parts for automobile and truck engines the classical quench and tempering (QT) of low‐alloyed steels is nowadays ‐ in a lot of plants in Europe ‐ substituted by direct continuous cooling (CC) of microalloyed steels without the necessity of additional heat treatment and expensive straightening as well as stress relieving cycles. Nevertheless, there are some limitations on strength and toughness achievable by this technique. On two commercial medium‐carbon (0.3%C) steels microalloyed with vanadium or vanadium and titanium, modified deformation parameters were applied. The mechanical properties, determined by the tensile test, can be improved by decreasing the deformation temperature. Nevertheless, the values of yield strength (resp. 0.2%‐proof stress) as well as reduction of area remain inferior to those after QT of the same steels.
Thermodynamic assessment of the Al deoxidation reaction in liquid iron
Authors: Seo Jeong‐Do , Kim Seon‐Hyo , Lee Kwang‐Ro
Published: December 2016

The deoxidation reaction of aluminum in liquid iron has been investigated thermodynamically using Al2O3 crucible at 1873 K under Ar atmosphere as a fundamental study for the accurate control of inclusions in the ladle refining process. In addition to the equilibrium constant log KA1 for the aluminum deoxidation reaction, the first‐order and second‐order interaction parameters between aluminum and oxygen were experimentally determined in the concentration range of aluminum up to 1 %. The temperature dependence of the equilibrium constant and the first‐order interaction parameter eA1 was also obtained: log KA1 = 12.32 ‐ 47400/T, eA1 = 15.57 ‐ 36500/T.

The equilibrium relation between aluminum and oxygen contents in the aluminum deoxidized iron by applying interaction parameters and the equilibrium constant determined in this work satisfies fairly well the equilibrium data over the whole concentration range of aluminum considered.
Effect of soaking temperature and annealing atmosphere on magnetic properties of semi‐processed nonoriented electrical steel containing 0.4 % silicon
Authors: Park Jong T. , Woo Jong S. , Chang Sam K.
Published: December 2016

In order to investigate the effect of soaking temperature and annealing atmosphere on magnetic properties of the semi‐processed nonoriented electrical steel containing 0.4 % silicon, customer annealing was carried out at a temperature ranging from 730 to 950 and in different annealing atmospheres. As the soaking temperature increases from 730 to 950 in the dry N2 atmosphere, the core loss at 1.5 Tesla decreases continuously, whereas the permeability at 1.5 Tesla increases up to 890 and then decreases significantly at 950 °C. Among DX atmospheres having a dew point of ‐23 °C, the air to LPG ratio of 19.5 is found to reveal the best magnetic properties due to the lowest carbon content. At a dew point of +5 °C and an air to LPG ratio of 18.5 the best magnetic properties are to be achieved regarding both carbon content and internal oxidation layer.
The realistic simulation of metalforming process chains
Authors: Kopp Reiner
Published: December 2016

In this paper some actual developments concerning realistic simulation of metal forming processes by use of the finite element method are discussed. An algorithm, which was developed at the IBF, for visualisation of the material flow in a process chain is illustrated by means of the example of manufacturing a profiled ring. Further it is shown that for faster analysis also of massive forming processes the use of an explicit finite element formulation is sensible. Another contribution for realistic simulation is coupling the finite element method with physically‐based material models. The integration of a dislocation density model in a finite element model is illustrated by means of the example of a hot rolling process.
Efficient steel processing by disciplined hot forming and microalloying
Authors: Kasper Radko , Peters Andreas
Published: December 2016

The application of thermomechanical treatment (TMT) is an example for an efficient way of steel processing. However, decisive for this is the fact that the course of the microstructural processes in hot rolled steels is not determined exclusively by the deformation parameters, but in a strong way by the material itself. The addition of microalloying provides an efficient way of enhancing the effect of TMT on the microstructural processes. The choice and dispensing of individual microalloying elements in hot rolled steels depend on desired properties and parameters of TMT. On the other hand, in most cases, the TMT must be modified to make full use of microalloying. In this paper, some general guidelines are given for an optimized link between the hot deformation and microalloying of steels. Using the example of the processing of a spring steel, the common effect of TMT and microalloying leads to a significant increase in fatigue strength, combined with a notable shortening of the manufacturing process.
Measuring the friction coefficient in the case of plastification of metals by elastomers
Authors: Pawelski Hartmut
Published: December 2016

The friction measuring apparatus according to O. Pawelski, which is based on the strip drawing experiment, is used to determine friction coefficients in plastic shaping of metals. By implementing elastomer inlays into the drawing cheeks the same principle has been applied to the contact between metals and elastomeric media. The plastification of metal by the extremely shear‐weak elastomer is possible, because it is completely constrained with metal, so that a sufficiently high hydrostatic pressure in the inlay is generated. Elementary theory in combination with FEM showed that the friction coefficient, calculated using only the global static equilibrium of forces, is in very good approximation with simply the mixture of the friction coefficient between metal strip and elastomer and the friction coefficient between metal strip and drawing cheek weighted with the corresponding contact areas. Drawing experiments with aluminium 99.5 or steel St 37 and polyurethane or soft rubber were carried out. The important influence of lubrication and roughness of the metal strip on the friction coefficient was investigated.
A general material law of plasticity and its numerical application
Authors: Besdo Dieter
Published: December 2016

FE‐codes for numerical simulations of metal forming processes need very general material laws. In this paper constitutive equations are proposed which include real‐time and endochronic effects as well as kinematical hardening and a variable Hill‐anisotropy. The law presented here is denoted in terms of strain spaces. The objective rates occurring in the evolutional rules of internal parameters include the concept of plastic spin to avoid physically meaningless oscillations of stresses in case of shear processes. Additionally an integrational scheme is presented which works very robustly and highly precisely even if very large strain differences occur within one time‐step of the integration.
Modelling of flow curves for hot deformation
Authors: Schotten Karl , Bleck Wolfgang , Dahl Winfried
Published: December 2016

A new mathematical model for hot deformation flow curves is presented. The developed expression can be used for austenite or ferrite deformation, for monotonically increasing flow curves as well as for those with a maximum or with oscillating shape. By experimental determination of 4 flow curves, the parameters for the flow curve field can be calculated. Experiments have been carried out using aluminium‐ killed mild steels in hot compression tests with a range of deformation temperature between 700 and 1250°C and of strain rate between 0.1 and 20 s‐1. The accuracy of the new approach and the ability to meet the different flow curve shapes proved to be very good.
Distribution of metal onto the belt of a horizontal strip caster
Authors: Holmberg N. Anders
Published: December 2016

This paper presents a new method for metal distribution onto the belt of a horizontal single belt strip caster. Water and liquid tin have been used to study the flow conditions in the feeding zone on the conveyor belt. Tests of a method presented in literature for metal distribution have been conducted and a new method that uses multiple parallel jets in order to obtain stable feeding conditions have been tested. This method gives a controlled way of maintaining a continuous liquid film and it also has a stable meniscus. The freezing problem with a triple point will also be eliminated by use of this method.
Theoretical model of steel desulphurisation with gaseous calcium
Authors: Kalicka Zofla
Published: December 2016

A model of desulphurisation of steel with gaseous calcium bubbles based on a population balance equation is presented. The equation is a basis of the quantitative approach to the phenomena observed in the dispersive systems. The course of reaction of the calcium bubbles with the oxygen and sulphur during the Stokes float‐out was studied for various model parameters. The effect of the following factors on the refining process efficiency was considered: interval of bubble sizes, distribution of bubble sizes and participation of a carrier gas. It was found that the refining process is affected mainly by the global bubble surface and the residence time of bubbles in the steel. It means that the bubble size interval and size distribution of the bubbles for the calcium mass is a decisive factor for the desulphurisation efficiency. Any increase in the carrier gas content, in fact, increases the bubble surface, yet, simultaneously accelerates the float‐out of the not reacting bubbles. Thus, for the Stokes model the effect of a carrier gas on the desulphurisation efficiency is small. The comparison of the calculated and experimental results for different blowing depths and different amounts of calcium is presented.
Removal and retrieval of tin from tinned steel sheet by electrolyzing with caustic solution
Authors: Chen Qibing , Ma Zhongting , Ni Ruiming , Wei Shoukun
Published: December 2016

It is experimentally confirmed that tinned steel sheet can be completely purified by electrolyzing with caustic solution. The concentrations of NaOH‐Na2CO3‐ and Na2SnO3 3H2O, and the temperature of electrolyte are important factors to influence the critical current density of passivation of Sn layer. These parameters are optimized by experiments with the orthogonal method.
Reaction mechanism of FeO reduction by solid and dissolved carbon
Authors: Seo Jeong‐Do , Kim Seon‐Hyo
Published: December 2016

The reduction reactions of FeO by carbon have been studied in order to be able to understand the fundamental phenomena occurring in smelting reduction process. The reduction of pure FeO by solid carbon proceeds mostly according to the same reaction mechanism as that by dissolved carbon in iron, the rate of which was experimentally determined to be controlled by the interfacial chemical reaction between Fe‐C melt and intermediate CO2 gas. Hence, the reduction rate of pure FeO by solid carbon is also chemically controlled by the Boudouard reaction between the dissolved carbon and CO2 at the interface of by‐product Fe droplet/gas phase, the activation energy of which was found to be about 193.2 kJ/mol. In addition, the reduction reaction of FeO in CaO‐SiO2‐Al2O3‐FeO slags by the dissolved carbon in Fe melt was also investigated over the FeO mass content less than 20 %. The reduction rate shows first order dependence with respect to FeO concentration. The surface active sulphur content in iron does not affect the reduction rate, and the temperature dependence of reduction rate gives the activation energy of 24.78 kJ/mol. Therefore, the reduction rate of FeO in slags by the dissolved carbon can be safely mentioned to be controlled by the liquid phase mass transfer of FeO through the slag phase diffusion‐resistant boundary layer over the limited FeO concentration range. The empirical expression for the mass transfer controlled reactioe, deren Aktivierungsenergie ca. 193.2 kJ/mol beträgt. Außerdem wurde die Reduktion von FeO in CaO‐SiO2‐Al2O3‐FeO‐Schlacken mit dem in der Eisenschmelze gelöstem Kohlenstoff fär FeO‐Massengehalte von weniger als 20% untersucht. Die Reduktionsgeschwindigkeit weist hinsichtlich der FeO‐Konzentration eine Abhängigkeit 1. Ordnung auf. Der Anteil an oberflächenaktivemn rate was determined as r = 5.94(±0.07).10−6.exp(‐24780/RT).(%FeOP)0.96 over the reaction conditions employed.
Precipitation behaviour of a nitrogenated surface layer of 1.4462 duplex stainless steel
Authors: Machado Izabel Fernanda , Padilha Angelo Fernando , Kliauga Andréa Madeira
Published: December 2016

A duplex stainless steel sheet containing masses of 22%Cr‐5.5%Ni‐3%Mo was nitrogenated at 2 bar partial pressure of N2 at 1200°C for 5 hours. Three zones, with different microstructures and nitrogen contents, were formed: a fully austenitic nitrogen rich zone, a transition zone composed of an austenitic matrix containing islands of remaining ferrite and a nitrogen enriched duplex inner zone. The exposures of the nitrogenated material at temperatures below the nitrogenation temperature caused precipitation of ε‐(Cr,Fe)2N hexagonal nitride and of sigma phase. The nitride precipitation occurred both continuously and discontinuously. TTT diagrams for the austenitic external zone and for the inner ferritic‐austenitic zone have been proposed.
Parameters affecting manganese oxidation in top blown basic oxygen converter
Authors: Eissa Mamdouh
Published: December 2016

The data obtained from 84 heats carried out in a 90‐t top blown basic oxygen converter were used to study the effects of slag composition and temperature on the activity coefficient and activity of manganous oxide in the slag as well as on the manganate capacity and the manganese distribution between slag and metal. In addition, the dependence of manganese activity in the metal on the concentration of maganese and temperature was also investigated.

The present study carried out in wide ranges of temperature, 1350–1690°C, and slag basicity expressed as (CaO)/(SiO2), 1.4–10.6, clarifies the dependence of MnO activity coefficient mainly on temperature. The activity coefficient of MnO increases by decreasing the temperature. On the other hand, activity of MnO increases by increasing MnO concentration and temperature. Both activity coefficient and activity of MnO in the slag slightly increase by increasing the slag basicity. At constant temperature, the activity of Mn in the molten metal varies linearly with Mn concentration and tends also to increase with increasing temperature at constant Mn concentration. The increase in manganese activity by increasing Mn concentration is much steeper at high temperatures. The manganate capacity as well as manganese distribution ratio decrease with increasing temperature at constant basicity and tend also to slightly decrease with increasing slag basicity at constant temperature. Equations describing the parameters affecting activity coefficient and activity of manganous oxide in the slag, manganese activity in the metal, manganate capacity and manganese distribution ratio have been derived.
A mathematical model of calcination of limestone in rotary kiln
Authors: Lee Manseung , Lee Sihyung
Published: December 2016

A mathematical model of the rotary kiln for the calcination of limestone was developed by considering calcination kinetics, mass and energy balance of solid and gas. A system of strongly nonlinear equations with two point boundary conditions were numerically solved. The measured outlet temperature of gas and calculated combustion temperature were used as boundary conditions. By applying this developed model, the axial temperature profiles of gas, solid and wall and the axial concentration profiles of solid and gas were calculated from operating conditions. The temperature of outer wall and limestone conversion calculated by model were in good agreement with those measured from running rotary kiln at Kwangyang Steel Works.
Kinetics of smelting reduction of fluxed composite iron ore pellets
Authors: Goswami Manik Chandra , Prakash Swatantra , Sarkar Samar Bijoy
Published: December 2016

Kinetic studies on smelting reduction of unreduced fluxed composite pellets (FCP) and fluxed composite pre‐reduced iron ore pellets (FCRIP) have been carried out in an induction furnace. The pellets are charged into the slag layer floating on the carbon saturated molten iron bath in a graphite crucible. The slag basicity was however varied such that it has the same value as that of the pellets charged. The temperature of the slag is varied within the range of 1623K to 1823K for the pellets of basicity 2.0. Kinetic studies show a mixed kinetic model of both diffusion and chemical reaction controlled. While the smelting of FCRIP follows the model expressed as G(or) = 1‐(2/3)(α) ‐(1‐α)2/3, the unreduced FCP pellets initially follow the diffusion controlled model of G(α) = α2 followed by a chemical reaction controlled first order model of ‐ln(1‐α) at the latter stages of smelting reduction, where α denotes the degree of reduction. The basicity dependence on the kinetics is not very significant. Comparison of the activation energy values explains that the smelting reduction with pre‐reduced pellets seems to be a rather less energy intensive process.
Estimation of escape rate of volatile components from slags containing CaF2 during viscosity measurement
Authors: Viswanathan Nurni Neelakantan , Fatemeh Shahbazian , Sichen Du , Seetharaman Seshadri
Published: December 2016

In continuous casting process, the viscosity of the mould powder/flux has direct impact on the size of the gap between the mould wall and the solidified shell, which in turn affect the heat transfer characteristics between the metal and the mould. Numerous experiments have been conducted to determine the viscosity of various mould powders using rotation cylinder method. The pre‐melting of the mould powder as well as the viscosity measurement are carried out in a cylindrical crucible placed in a tubular furnace with constant argon flow to maintain inert atmosphere. One of the main difficulties encountered during viscosity measurement is the liberation of volatile fluorides, which in turn changes the flux composition, and consequently the viscosity of the flux. Thermodynamic calculations have shown that SiF4 and HF are major constituents of the volatile matter. Present study aims to estimate the liberation rate of SiF4 and HF from flux samples during viscosity measurement by computing the detailed gas flow pattern inside the tubular furnace. The gas flow pattern is computed by solving momentum and continuity of equations. Further, the effect of argon gas flow rate and slag level in the crucible on liberation rate has been studied to arrive at proper experimental conditions during viscosity measurement.
The effect of carbon content on the rate of reduction of FeO in slag relevant to iron smelting
Authors: Smith Richard H. , Fruehan Richard J.
Published: December 2016

In the iron smelting, or bath smelting, process the tapped metal contains high amounts of sulfur and the slag contains high amounts of FeO, relative to blast furnace slag. After tapping, the FeO can be further reduced by carbon in the metal, which will also lead to better desulfurization. Although there have been many studies of the reaction of carbon in iron with FeO in slag, discrepancies exist with regards to the effect of carbon in iron on the rate of FeO reduction in slag, which is the subject of this study. Experiments were conducted at 1723 K, using a slag with basicity close to one with an FeO mass content of 5 %. The rate of reduction was measured using a pressure increase technique. For moderate and high sulfur contents, as in the case of iron smelting, the rate is primarily controlled by the dissociation of CO2 on the surface of the molten iron. Furthermore, if the effect of carbon on sulfur is taken into account, for the range of carbon mass contents of 2 to 4.5 %, there is no effect of the carbon level on the rate of FeO reduction. At low sulfur contents it was found that there is considerable slag foaming, which inhibits mass transfer of FeO in the slag, and significantly reduces the rate. Even when there is no slag foaming at low sulfur contents, mass transfer of FeO in the slag can influence the rate of FeO reduction.
UV/VIS‐spectroscopy of liquid slags
Authors: Okretic Stefano , Nowack Norbert
Published: December 2016

UV/VIS‐spectroscopical methods have been applied to investigate the absorption behaviour of CaO‐Al2O3‐SiO2‐slags in a wide temperature range from 20 to 1655°C. The observations reveal a strong temperature dependence of the absorption bands, which can be explained by means of a newly developed theoretical model. The model also correlates the observed long‐frequency UV cutoff‐wavelength with the optical basicity. The definition of the optical basicity has been corrected for higher temperatures, since there are remarkable deviations between the solid and the liquid state, which have not been taken in consideration yet.

Further investigations on a CaO‐Al2O3‐slag containing CaF2 at 1500°C show that no Fe3+… F‐complexes like Fe3+(F−)4 or Fe3+(F−)6 are formed. F− reacts with Al3+ forming Al‐O‐F‐complexes. The F−‐ions displace the O2‐‐ions from the Al3+. This causes the basicity to increase.
Steel strips in the context of near net shape casting production
Authors: Guthrie Roderick I.L. , Isac Mihaiela
Published: December 2016

Following the replacement of ingots by continuously cast slabs the next logical step towards near net shape casting has been the development of thin slab casting machines. These are now beginning to match the quality and productivity levels possible with conventional machines. The next step in this evolution towards lower cost operation is high speed thin strip casting machines. The merits of twin roll casters versus belt casting machines for friction free casting of low carbon steels, suggest that a belt caster will be needed for achieving high productivities and associated cooling lengths required for the production of hot strip in the 5–20 mm thickness range.
Simulation of transverse crack formation on continuously cast peritectic medium carbon steel slabs
Authors: Suzuki Mikio , Hayashi Hiroshi , Shibata Hiroyuki , Emi Toshihiko , Lee In‐Jae
Published: December 2016

Reliable data are limited to the critical strain for the formation of transverse cracks on the slabs, owing to experimental difficulty to simulate temperature gradient in solidified shell in continuous casting mold. The present study is to determine the critical strain, ɛc, for the formation of transverse cracks on continuously cast slabs. A convenient and simple hot tensile test using rectangular test pieces with either V‐notch or semi‐circle notch or oscillation marks has been developed by placing the specimen under similar temperature gradient to that in solidified shell in the mold. The ɛc has been determined at a better accuracy and reproducibility, and the ɛc at a strain rate of 5•10−4s−1 is found to be a high 35% for test pieces without notch. It sharply decreases, however, to 10% for those with V‐ and semi‐circle‐notches, slightly decreases with increasing notch depth, and further decreases for those with oscillation marks that accompany solute segregation. Reduction of the oscillation mark depth is shown to be important measure to prevent the occurrence of transverse cracking of continuously cast slabs.
Sheet metal forming behaviour and mechanical properties of TRIP steels
Authors: Bleck Wolfgang , Ohlert Joachim , Papamantellos Kostas
Published: December 2016

Recently various kinds of high‐strength sheet steels have been developed to meet the requirements of the automotive industry such as passive safety, weight reduction and saving energy. Usually the main problem of high‐strength steels is their inferior ductility. Multiphase steels however show a very good combination of strength and formability so that the applicable region of high‐strength steels has been widely enlarged. Multiphase steels have been developed for various purposes because of their ability to tailor properties by adjusting the type, the amount, and the distribution of different phases. Especially new developed triple‐phase steels which make use of the TRIP effect (transformation induced plasticity) can further improve formability as well as strength due to the transformation of retained austenite to martensite during the deformation. In this work the transformation behaviour and the mechanical properties of low alloyed TRIP steels were investigated. The influence of the annealing parameters on transformation behaviour and on the amount of retained austenite were determined. In addition the temperature dependence of the mechanical properties and the effect of testing speed on the formability were studied. The investigation was carried out on seven different TRIP steels with different chemical compositions, especially the influence of the microalloying element niobium was considered. For reasons of comparison various mild and high‐strength steels were tested parallel to the TRIP steels. It was found that the investigated TRIP steels offer very attractive combinations of elongation and strength values. An interesting temperature dependence of the mechanical properties can be observed, in such a way that the elongation values of the TRIP steels possess a maximum between +50 and +100°C. Due to its effect on grain size and on precipitation behaviour the addition of niobium leads to higher strength values without a strong decrease in ductility. In general, the mechanical properties are strongly affected by the type and the distribution of the different phases. The most important parameters, however, to influence the mechanical behaviour are the amount and the stability of the retained austenite, which are mainly controlled by the heat treatment and the chemical composition.
Contributions by Eberhard Schürmann to foundry science
Authors: Döpp Reinhard
Published: December 2016

A survey of Eberhard Schürmann's metallurgical work in the field of foundry science is given. Metallurgical principles of melt/slag‐reactions, thermal analysis and solidification behaviour, back plate (shell) moulding and coke and cokeless cupola are specially referred to.
Investigation into TRIP steels won steel research Best Paper Award 1999
Authors: Garbracht Kerstin
Published: December 2016

Research results are commonly circulated on the occasion of congresses or by publication in technical journals. steel research, the scientific journal edited by the Verein Deutscher Eisenhüttenleute, VDEh ‐ The German Iron and Steel Institute, and the Max‐Planck‐Institut für Eisenforschung, MPI, presents the latest results of fundamental research in the fields of process metallurgy, metal working and materials science as far as the material steel is concerned. Formerly well‐known as „Archiv für das Eisenhüttenwesen“, steel research looks back on 70 years of experience in worldwide exchange of technological basics. In 1995, the editors decided to offer a Best Paper Award with 1.000 US‐$ purse and a pretty diploma.

This year, it was for the fifth time that authors have been awarded with the steel research Best Paper Award. The Editorial Board has chosen a contribution to TRIP steels from the papers published in the 1999 annual volume.
On the reactions 2 C + O2 and C + CO2 at very low pressure
Authors: Knacke Ottmar , Lemperle Michael , Seidl Ursula
Published: December 2016

In an ultra high vacuum heterogeneous gas reactions such as 2 C + O2G → 2 COG and C + CO2G → 2 COG often show a less complicated reaction path than under normal pressure. In the present study the graphite sample is a commercial light‐bulb filament, which is extremely resistant against oxidation. Under low pressure the combustion reaction is of first order with a continuous transition to zero order at temperatures between 900 and 1300 K depending on the oxygen pressure. The Boudouard reaction behaves similarly but obeys zero order only around 2000 K and for CO2 pressures around 1 bar. The measured and the statistically calculated reaction rates agree well. An insight of the details of the reaction and chemisorption is determined by the evaluation of experiments carried out in an ultra high vacuum using isotopes such as 13CO2G. The Boudouard equilibrium for graphite can be reached only catalytically, e.g., with sponge iron in statu nascendi.
Proof strength values for austenitic stainless steels at elevated temperatures
Authors: Eliasson Johan , Sandström Rolf
Published: December 2016

The influence of the alloying elements C, N, Si, Mn, Cr, Ni, Mo, Cu, Ti on proof strength is studied in the temperature range 20–550 °C. High temperature data for the proof strength of austenitic stainless steels have been analysed. Using computational thermodynamics the amount of alloying elements in solid solution and the volume fractions of precipitates were assessed. These quantities were then applied in a regression analysis for the high temperature strength. Quantitative relationships for the proof strength as a result of the regression analysis are proposed as a function of temperature. They are to be used in materials design. The interstitial elements showed the largest effect. Si, Ni and Mo increased the strength at all temperatures. Cu and Mn reduced the strength and Cr gave an influence, which varied with temperature.
Kinetics and mechanism of reactions between iron oxides and iron‐carbon melts
Authors: Mourão Marcelo Breda
Published: December 2016

The reaction between iron oxides and iron‐carbon melts was studied in the temperature range 1523–1973 K. Pellets made from three different sources of iron oxides were added onto the melt surface, and the reaction time was measured through the constant volume pressure increase (CVPI) method. The effects of reaction temperature, oxide and melt surface areas, oxide type and weight on reaction time were evaluated. Analysis of partially reduced pellets through SEM was also performed. It has been determined that the reaction time increases as the pellet weight increases, and decreases as the temperature, the contact area between the oxide and the melt and the surface area of the melt increase. Examination of partially reduced pellets had shown that the reduction occurs topochemically. Based on the results, it is proposed that the overall reaction rate is determined by the consecutive reactions of dissociation of FeO and formation of CO.
Thermodynamic behaviour of Cu in molten Fe‐C‐S alloys at high temperatures
Authors: Huh Ki Haeng , Min Dong Joon
Published: December 2016

The activity of Cu in molten Fe‐C‐S alloys at high temperatures was measured by a thermochemical equilibration technique. The effects of the contents of Cu, C, and S in the molten alloy as well as temperature on the activity coefficient of Cu in pure and carbon‐saturated iron were determined by measuring the distribution ratio of Cu between molten silver and Fe‐C‐S alloy melts. In molten pure iron and carbon‐saturated iron, the activity coefficient of Cu under infinite dilution, was measured as 11.0 and 28.5, respectively, at 1823K. The interaction parameters between Cu and Cu, S, C in the molten iron at 1823K were estimated: . The dependence of in molten Fe‐C alloy on temperature was determined as follows:

pure iron: , carbon‐saturated iron: .

Combining the effects of temperature and those of alloying components, the activity coefficient of Cu in the molten Fe‐C‐S alloy could be estimated as follows: .
The solubility of water vapour in CaO‐SiO2‐Al2O3‐MgO slag system
Authors: Jo Sung‐Koo , Kim Seon‐Hyo
Published: December 2016

The solubility of water vapour in the CaO‐SiO2‐Al2O3‐MgO quaternary slag system was measured using an inert gas fusion technique with thermal conductivity detection. The slags were equilibrated with argon‐water vapour mixture corresponding to 0.157 bar of water vapour pressure at 1873 K. The slag solubility of water vapour is proportional to the square root of vapour pressure. Since the hydroxyl capacity of slag, COHshows an independence on the relative amount of CaO or MgO in slag, the contributions of CaO and MgO on the hydroxyl capacity are equivalent on a molar basis. Whereas, Al2O3shows a better effect on the hydroxyl capacity than SiO2. A linear relationship between hydroxyl capacity and slag basicity in logarithmic scale was obtained with the slope of 1/2, confirming the water vapour dissolution reaction into a basic slag as (O2‐) + H2O(g) = 2(OH−). The correlation between hydroxyl capacity and slag components was derived in terms of their contributing weight factors. The measured values ofC'OHagree well with the calculated ones using the interaction energies ofαH‐Al= −38300 andαH‐Mg= −22700 J determined with the aid of the regular solution model. In addition, the correlation between hydroxyl capacity and sulphide capacity was empirically derived as a formula of logCOH= 1/2logCS+ (4.38 ± 0.25) through the thermodynamic expression of both capacities by virtue of the common oxygen ion activity.
Relation between steel/slag interfacial tension and the sulphur absorption rate in dependence of the Si and Mo concentration
Authors: Wosch Erwin A.T. , El‐Geassy Abdel Hady A. , Gammal Tarek El
Published: December 2016

The relation between the interfacial tension at the steel/slag interface and the sulphur transport through the phase boundary has been investigated. The experiments have been carried out at 1550°C. The steel/slag system consisted of Armco iron in combination with a synthetic slag containing 40% CaO, 40% SiO2 and 20% Al2O3. The controlled change of the interfacial tension was performed by additional alloying of the surface active element silicon and surface inactive molybdenum.

The different influences of silicon and molybdenum on interfacial tension are directly reflected by the sulphur transport rate. Higher interfacial tensions generally cause a lower sulphur transport rate. A linear relationship was only obtained in presence of silicon.
Effect of H2S on formation and decomposition of Fe3C and Fe5C2 under metal dusting conditions
Authors: Schneider André , Inden Gerhard , Grabke Hans Jürgen , Wei Qing , Pippel Eckhard , Woltersdorf Jörg
Published: December 2016

The high temperature corrosion process metal dusting leads to the formation and decomposition of metastable iron carbides at the surface of iron samples. A small amount of H2S in the carburising atmosphere causes the adsorption of sulphur onto the sample surface, which decreases the carbon transfer rate and retards or suppresses the start of metal dusting. The extent of retardation of metal dusting depends on temperature, carbon activity and H2S content. The higher the carbon activity the higher the H2S content required for suppression of metal dusting. At very high carbon activities a second iron carbide, Fe5C2 (Hägg carbide), forms on the cementite surface. The carburisation experiments were conducted at 500°C using CO‐H2‐H2O‐H2S gas mixtures. The microstructural investigations show that both metastable carbides decompose during metal dusting.
Deep‐drawing quality of cold rolled sheet made of ferritically rolled hot strip
Authors: Tomitz Andreas , Kaspar Radko
Published: December 2016

In the so‐called ferritic rolling the finishing is shifted down into the temperature region of ferrite, which enables a production of thinner hot strips (compared to the conventional hot rolling in austenite) with a changed texture development. The present study is focused on the effect of the process parameters of such initial warm rolled hot strips on the texture formation and hence on the deep‐drawing quality of the final cold strips. A special attention is given to the transmission of the hot strip texture to the cold strip. The investigation was carried out on commercial IF‐ and ELC‐steels by a laboratory simulation with the hot deformation simulator Wumsi (rolling simulated by the plane strain compression test). It was possible to optimize cold rolling and subsequent annealing by means of the measurements of the texture development during the ferritic (warm) deformation as well as the parameters of the processing route of such special production of cold strips by means of the calculation of r‐values. If compared with the conventional processing route, a considerable improvement of deep‐drawability with a diminished earing is achievable especially with the IF‐steel.
Steel for a billion people: a brief appraisal of Indian steel research
Authors: Chakraborti Nirupam
Published: December 2016

A compact overview of the iron and steel industry in India is presented along with the current status of research and development activity.
Physical and mathematical modelling of flow and residence time distributions in different tundish designs
Authors: Robert Asish , Mazumdar Dipak
Published: December 2016

A steady state, three‐dimensional, turbulent flow model has been developed in‐house for analysis of melt flow and residence time distribution phenomena in steelmaking tundish system. The governing equations of flow, turbulence and tracer dispersion were derived in terms of the Cartesian co‐ordinate systems and solved numerically with their associated boundary conditions adapting a control volume based finite difference procedure. In the numerical solution scheme, the pressure‐velocity coupling was treated via the popular Simple (semi implicit method for pressure linked equations) algorithm.

Prior to carrying out elaborate numerical predictions for tundish geometry, the model was applied to several standard test problems and evaluated against corresponding bench mark results. Thus, several typical test problems such as, flows in a cubic cavity, flows in ducts of rectangular cross‐section, flow over flat plate and so on were simulated numerically to assess the adequacy and appropriateness of the computational procedure developed. Results thus obtained together with the bench mark solutions indicated that the mathematical model is internally consistent and sufficiently robust. Accordingly, the turbulent flow model was applied to simulate flow and Residence Time Distributions (RTD) in four different tundish designs . These included, a single strand and a two strand slab casting tundish systems, a six strand rectangular shaped tundish and a six strand delta shaped billet casting tundish. Various RTD parameters (e.g., minimum break through time, tmin, time at which peak concentration occurs, tpeak and average residence time, tav) were computed numerically in the four tundish systems and these were subsequently compared with corresponding experimental measurements derived from equivalent water model tundish systems. Except for the single strand tundish system, large differences between measurements and prediction (particularly on tmin and tpeak) were noted for the other three tundish geometries. Furthermore, the extent of such discrepancy was found to be relatively more pronounced for the multi‐strand tundish system. The possible reasons for such discrepancy is discussed in the text and it was shown computationally that relatively better agreement between theory and measurement can be achieved if, instead of the high Reynolds number k‐ε turbulence model, a low Reynolds number turbulence model is applied in the computational procedure.