bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermodynamic behaviour of phosphorus in Mn‐Si‐Ca‐P melts
Authors: Ma Zhongting , Ni Ruiming , Cheng Wu , Wei Shoukun
Published: December 2016

Thermodynamic experiments of Mn‐Si‐Ca‐P melts were carried out in Mo‐wire‐heated furnace. With these experimental data, the first and second order activity interaction coefficients of Ca, Si and P upon P under the conditions of the same activity and the same concentration method were evaluated. The standard free energy of solution of P in liquid Mn based on 1 wt.% solution standard formulated in temperature was given and it only holds near 1623 K.
Application results of Al2O3 porous plug containing TiO2, Al2O3 and MgO as matrixes on an actual operation
Authors: Tsuchinari Akihiro , Hokii Toshiyuki , Eba Atsushi , Imai Hiroyuki , Kanaoka Chikao
Published: December 2016

Al2O3 porous plugs containing TiO2, Al2O3 and MgO in the matrix were applied for 200‐t ladle (improved porous plug). Although cracks occurred in longitudinal and transverse direction in the conventional porous plugs, no cracks were observed in the improved porous plug. Therefore, the latter was superior to the conventional one in thermal shock resistance. Wear rate was 9.0 mm/heat for improved plug and 9.8 mm/heat for the conventional one in average. The improved plug showed higher corrosion resistance than the conventional one. With the improved porous plug O2 cleaning was only necessary after every two heats. This was due to the high penetration resistance.
Influence of running water on the heat transfer in continuous casting
Authors: Heidt Viktor , Jeschar Rudolf
Published: December 2016

The influence of running water on spray water cooling is experimentally looked at with the aid of a stationary working experimental plant. The running water was fed separately to the sample from above as a defined water film by using a slot nozzle. In addition to the spray nozzle pre‐pressure, the velocity of the running water at the slot nozzle exit and the temperature of the running water, the angle of inclination of the sample plane was also varied. By employing three different full cone spray nozzles and setting different nozzle distances, a range of 450 to 2000 l/(m2·min) of the water impingement density was covered. To estimate the marginal influences, samples of 20 × 20 mm as well as 30 × 30 mm were used. Studies of initially pure spray water cooling without the additional running water film revealed a dependency of the heat transfer on the spray water impingement density, the spray water velocity and also the angle of inclination of the sample plane. For nozzles with a low water impingement density, a superimposing of a running water film on the spray water revealed a sharp increase in the heat transfer coefficients compared to pure spray water cooling. For nozzles with a high water impingement density and, therefore, with a high heat transfer already even for pure spray water cooling, the increase of the heat transfer coefficient is minor.
Automatic FeO activity determinator for slag control
Authors: Iwase Masanori , Ogura Toshihiro , Tsujino Ryoji
Published: December 2016

An automatic facility for rapid determination of the activities of FeO in metallurgical slags has been developed, by employing an electrochemical technique incorporating stabilized zirconia as solid electrolyte, a mixture of Mo + MoO2 as reference electrode and an Mo rod as an electrical contact. With this equipment, one datum is obtainable within 5 minutes. In the present article, discussions were held on potential applications of this system to steelmaking process control. A particular emphasis is given to the control of FeO levels in slags used for secondary steelmaking and chromium levels in stainless steelmaking slags.
Validation of the thermomechanical microstructural model for closed‐die forging
Authors: Pietrzyk Maciej , Kedzierski Zbigniew , Glowacki Miroslaw , Kusiak Halina , Sinczak Jan
Published: December 2016

The objective of the paper is the assessment of the predictive ability of the thermomechanical‐microstructural model for the closed‐die forging process. The model combines the rigid‐plastic flow formulation with the finite element solution of the Fourier equation with the closed‐form equations describing processes of recrystallization and grain growth. Experimental validation of the mechanical and thermal components of the model is presented in earlier publications; present work focuses on the microstructural part. Experiment includes closed‐die forging of the carbon‐manganese steel samples and the measurements of the grain size on the cross‐sections of the forgings after the deformation. Spherical samples, which involve significant inhomogeneity of the strain and the temperature fields, have been chosen for a presentation of the results.
Contribution on the cold straightening of workpieces
Authors: Fries Volkmar , Ismar Heinz , Ripplinger Wolfgang
Published: December 2016

First the material model for elastic‐inelastic behaviour is explained against the background of cold straightening of plane workpieces. The change in geometry of the yield surface in the case of very small cyclic deformations and the influence of isotropic and kinematical work hardening are taken into account. Then case studies on numerical shakedown simulations and on the limits of cold straightening of plane workpieces follow using two material models. Finally the attainable permanent curvature is shown as a function of load and of the number of cycles. Residual stresses and the spring‐back resilience involved are taken into account.
Nitrogen transfer into plasma heated steel melts as a function of arc polarity
Authors: Neuschütz Dieter , Zhai Yuyou , Hauck Alejandro
Published: December 2016

Heating liquid steel in the tundish with argon stabilized plasma arcs is one example of the increasing importance of mobile and inert heating systems in metallurgy. Unwanted nitrogen pick‐up caused by infiltrated air, and possibly aggravated by the activating effect of plasma, should be minimized by selecting the optimum current mode and torch polarity. With this aim in mind, the nitrogen transfer kinetics have been investigated on 150‐kg low carbon steel melts at different nitrogen partial pressures as a function of arc polarity. The experimental plasma plant was equipped with a 2000‐A torch, housing a thoria stabilized tungsten electrode, and a counter electrode located at the bottom of the crucible. The torch could be operated with DC of either polarity or with AC. Kinetic models of nitrogen transfer have been developed, which show good agreement with experimental results. Arc polarity has a significant effect both on the rate of nitrogen pick‐up in the arc area (pumping effect) and on the mass transport in the melt (stirring effect). Of all configurations tested, the torch as cathode is the most suitable arc configuration for inert heating, since the particularly active N+ ions in the plasma are repelled by the melt surface. Furthermore, the relatively strong stirring effect of the plasma jet leads to the highest heat transfer efficiency. On the other hand, where controlled nitrogen pick‐up is required, the highest nitrogen transfer rates are obtained with the torch poled as anode.
Thermal modelling and stress analysis in the continuous casting of arbitrary sections
Authors: Aboutalebi M. Reza , Hasan Mainul , Guthrie R. I. L.
Published: December 2016

A three‐dimensional parabolic heat conduction model has been developed to analyze heat transfer and solidification in variously shaped continuous casters. A fixed grid source based enthalpy method was used to model solidification during a casting process. In order to correctly model arbitrary cross‐sectional shaped castings, a body‐fitted coordinate transformation (BFT) technique was employed to transform the physical space on to a rectangular computational domain. The transformed governing equations and boundary conditions were solved in the transformed plane. Two arbitrarily shaped casters, having dog‐bone, and hexagonal cross‐sections, were tested in this study. The governing equations were discretized using the control‐volume finite difference approach, wherein an implicit solution technique was employed to solve the set of discretized algebraic equations.

From the temperature field predicted by heat flow model, a quasi‐non‐linear stress analysis was carried out within the solidifying shell of the beam blank (dog bone) section. The effect of roller arrangement on the distortion of solidified shell was investigated.
Water model simulation of tundish flow under varying conditions
Authors: Godiwalla K. M. , Sinha S. K. , Sivaramakrishnan C. S.
Published: December 2016

Water model studies have been conducted to characterise the flow conditions in continuous casting tundishes under conditions of open and submerged nozzles. In this investigation simulations of practical problems of flow interruptions from the ladle, thermal inversions due to uninsulated ladle, and pneumatic agitation near the tundish end wall were conducted.

The studies showed that incorporation of suitable flow control devices brings about homogenisation of temperature and composition between strands in the above cases. This study also showed that agitation of the liquid at the end wall reduces the extent of stagnant zone in the tundish.
Direct charging of thin slabs of a Ti‐microalloyed low carbon steel for cold forming
Authors: Kaspar Radko , Zentara Norbert , Herman Jean Claude
Published: December 2016

With a near‐net‐shape continuous‐casting simulator and the hot deformation simulator Wumsi, laboratory simulation tests have been performed to determine the final microstructure and the mechanical properties of a Ti‐microalloyed low carbon steel for cold forming, produced in the process of direct charging of thin slabs. For two initial specimen thicknesses (45 and 25mm) restricted values of total strain ϕ∑ were available to improve the coarse as‐cast microstructure. In a series of deformation schedules ϕ∑ was divided systematically into two components: an austenite grain‐refining strain ϕγ–GF (above the recrystallization‐stop‐temperature TRS) and an austenite strengthening strain ϕγ–s (below TRS). After hot deformation accelerated cooling with simulated coiling was employed. It was found that the direct charging process guarantees a more complete dissolution of Ti(C,N) and so an intensifying effect of Ti‐microalloying in comparison to a conventional cold charging. Structure refinement by rolling performed predominantly in the temperature region of non‐recrystallized austenite (increasing ϕγ–s) leads to better hot strip strength and improved low temperature toughness properties accompanied with a slight deterioration of uniform elongation.
Calculation of metal forming processes by means of FEM
Authors: Greve Andreas , Haase Folker , Keßler Lutz , Schilling Robert
Published: December 2016

The simulation of metal forming processes with the finite element method (FEM) is becoming more and more significant for process analysis and optimising. With regard to the quality of the calculations care must be taken to select a suitable FE model. Possibilities for FEM applications will be shown using the examples of die bending sheets and profile bending. A practical extension of this application is the support of the FE systems user by access to a material database.
Fractal analysis on the fatigue fracture surface along the crack propagation direction
Authors: Hao Yao , Wang Zhongguang , Kang Yan
Published: December 2016

The fractal dimension along the crack propagation direction on the fatigue fracture surface of a dual‐phase steel was investigated by both vertical section profile method and secondary electron line scanning method. Results from the vertical section profile method showed that during the crack propagation, the fractal dimension of the fracture surface increases with increasing stress intensity factor, however, the secondary electron line scanning method presented somewhat different results of fractal dimension and was proved not feasible in all kinds of fracture surfaces, so this method is not suggested in calculating the fractal dimension of the fracture surface.
Microstructure‐strength relationships for LC and HSLA steels
Authors: Österle Werner
Published: December 2016

Unalloyed low carbon steel (LC) and high strength low alloy steel (HSLA) were investigated after systematically changing the microstructure by certain heat treatments. The microstructural parameters grain size and dislocation density as well as particle size and particle spacing were measured quantitatively and correlated with the yield strength obtained from tensile tests at ambient temperature. Three different relationships were used to describe the results. The Hall‐Petch and the Orowan relationship could only be applied to some of the investigated microstructures, whereas the work‐hardening formula which correlates flow stress with dislocation density was more generally valid, provided that dislocation density was measured in the deformed state. In several cases two alternative relationships could be used, showing that the microstructural parameters are mutually dependant. The widespread assumption that all strengthening mechanisms can be added up to give the yield strength as the sum of the single contributions was clearly disproved. The results of some previous work on thermo‐mechanically processed steels has been newly interpreted in the light of these findings.
Corrosion behaviour of low‐Cr high‐Al stainless steels in 65% boiling HNO3
Authors: Abdul‐Azim Ahmad Adel , Ghanem Wafaa Abd‐el Rahem , Abou‐Shahba Rabab Mohamed
Published: December 2016

The corrosion resistance of low‐Cr high‐Al steels has been tested in 65% boiling HNO3 solution. Comparison of this resistance and that of stainless steels 304, 430 and 410 under the same conditions reveals that Al has a beneficial effect on the corrosion resistance of Fe‐Cr‐Ni steels. The reduction of about 7% Cr can be compensated by about 5% Al provided that Ni is maintained at about 15–18%.
Phase relations in the system CaO‐SiO2‐ZrO2 at 1573 K
Authors: S. Shashidhara Pandit , K. Thomas Jacob
Published: December 2016

Zirconia‐based solid electrolytes with zircon (ZrSiC4) as the auxiliary electrode have been suggested of sensing silicon concentrations in iron and steel melts. A knowledge of phase relations in the ternary system MO‐SiO2‐ZrO2 (M = Ca, Mg) is useful for selecting an appropriate auxiliary electrode. In this investigation, an isothermal section for the phase diagram of the system CaO‐SiO2ZrO2 at 1573 K has been established by equilibrating mixtures of component oxides in air, followed by quenching and phase identification by optical miroscopy, energy disperse analysis of X‐rays (EDAX) and X‐ray diffraction analysis (XRD). The equilibrium phase relations have also been confirmed by computation using the available thermodynamic data on condensed phases in the system. The results indicate that zircon is not in thermodynamic equilibrium with calcia‐stabilized zirconia or calcium zirconate. The silica containing phase in equilibrium with stabilized zirconia is Ca3ZrSi2O9. Calcium zirconate can coexist with Ca3ZrSi2Og and Ca2SiO4.
Remelting of scrap containing tungsten and nickel in the electric arc furnace
Authors: Ostrovski Oleg
Published: December 2016

Remelting of the metallic scrap containing tungsten and nickel and thermodynamic properties of slag containing tungsten oxide are discussed. Tungsten and nickel in the metallic scrap have to be separated before the scrap may be used for melting of some steels (for example, high speed steel). To separate tungsten and nickel, such scrap (waste drills) was remelted in the 25 t electric arc furnace under oxidizing conditions. Tungsten was oxidised and transferred to the slag phase, while nickel remained in the metal. Further, the slag containing tungsten oxide was used in the melting of high speed steel. Metal containing nickel was utilized in the constructional steel production. Technology of the scrap remelting was developed on the basis of thermodynamic analysis of slag containing tungsten oxide and tungsten slag‐metal partition. It was found that the coefficient of tungsten distribution between iron and basic CaO‐SiO2‐FetO‐WO3 slag increases with increasing slag basicity. In the industrial oxidising heats a slag of high basicity was used, it secured 94% tungsten extraction from scrap to the slag.
Phase transformations and microstructure changes in a 12%Cr‐steel during tempering at 1053 K
Authors: Janovec Jozef , Richarz Barbara , Grabke Hans Jürgen
Published: December 2016

The evolution of the microstructure and the phase transformations in a 12% Cr‐steel during tempering at 1053 K for 30 s, 0.25, 1 and 2 h were studied. The investigations were carried out by transmission electron microscopy. For the identification of the different phases and the determination of their chemical composition electron diffraction and energy dispersive X‐ray spectroscopy were used. Four different types of precipitates were found: MX, M3C, M2X and M23C6. They showed the following time dependent precipitation sequence: MX → MX + M3C → MX + M2X + M23C6 → MX + M23C6. Changes in the chemical composition of the various precipitates were determined. The chemical composition of the M23C6 carbide was nearly constant, whereas it varied with time for the M2X and MX carbonitrides. Two different types of MX particles were identified: Ti,V‐rich precipitates in the quenched and short‐term tempered states and V,Cr‐rich particles in the longer‐term tempered states. Two types of orientation relationships between the ferrrite and the M23C6 were observed: and .
Heating and melting of wustite pellets in liquid slag
Authors: Xu Shuang , Holappa Lauri
Published: December 2016

The melting behaviour of the metallized, porous wustite pellets immersed in liquid slag, as well as the influences of the metallization ratio, pre‐heating temperature of the pellet and slag temperature were examined in this work by means of an X‐ray imaging system. The internal structure of the pellets after having been immersed in slag was checked by optical microscope and EPMA. The adoption of digital image processing improved the image analysis dramatically and, as a result, some important phenomena, such as solid slag shell forming and melting, slag penetration, wustite component dissolution as well as the influence of experimental conditions, were quantified.
Fatigue properties of laser‐beam weldments on high‐strength steels
Authors: Ring Markus , Dahl Winfried
Published: December 2016

The intention of this investigation is to evaluate the behaviour of laser‐beam weldments under cyclic loading. The materials tested are several high‐strength steel plates with thicknesses of 7‐8 mm differing in chemical composition, delivery state and strength level. A number of S‐N curves was established not only for the as‐welded condition but also for the stress relieved and dressed state. It was found that the fatigue properties of laser‐beam welded joints are considerably better than those of weld seams produced by other methods. The increase in fatigue strength amounts to approximately 50%, neither depending on the material used nor on an additional stress‐relief annealing. By using the R1 MS notch stress model, the good behaviour of the weld seams can be entirely attributed to the favourable weld geometry.
On the hot metal desulfurization
Authors: Oktay Enver , Fruehan Richard J.
Published: December 2016

Although there is no thermodynamic limitation to the desulfurization of carbon‐saturated iron with CaO, the process is well‐known to be slow. Consequently, the desulfurization of carbon‐saturated Fe‐S, Fe‐S‐Si, Fe‐S‐Si‐Al, Fe‐S‐Zr alloys by CaO, and Fe‐S‐Si alloys by CaO‐10 % CaF2 were investigated to determine the reaction mechanism. For this purpose, dense CaO and CaO‐10 % CaF2 discs were cemented to the bottoms of graphite crucibles containing the carbon saturated alloys. The desulfurization experiments were run at 1450°C in an SiC resistance furnace under argon gas atmosphere. The results indicate that the desulfurization of hot metal by CaO is greatly improved by prior addition of aluminum to the hot metal. The addition of 10 % CaF2 to CaO also increases the rate of desulfurization. Zirconium, which has a stronger affinity for oxygen than aluminum did not increase the rate. SEM and X‐ray diffraction studies on the surfaces of CaO discs used to desulfurize carbon‐saturated Fe‐S, and Fe‐S‐Si alloys showed that solid CaS, and solid CaS plus small amount of solid 2 CaO · SiO2 compounds form on the lime surface, respectively. The slow reaction rate with CaO is attributed to the solid reaction products which block the reaction by preventing the occurrence of interfacial turbulence.
Study on phosphate and sulphide capacities of CaO‐CaCl2 slags
Authors: Yang Yindong , McLean Alex , Sommerville Iain D. , McKague Alan R.
Published: December 2016

Experiments were carried out at 1175–1350°C to study the phosphate capacity of CaO‐CaCl2 slags and the sulphide capacity was calculated according to the correlation between the two capacities. At 1200°C the logarithm of the phosphate capacity increased from 24.5 to 26.5 with increasing CaO mole fraction from 0 to 0.22 in the slags and it decreased with increasing temperature. Sulphide capacity increased both with increasing CaO mole fraction and temperature.

A good linear correlation was found between slag carbonate capacity and phosphate capacity as well as sulphide capacity. Optical basicity was used to evaluate the property of the CaO‐CaCl2 slag in the present study. The value of optical basicity of CaCl2 is established as 0.63. The correlations of optical basicity with above mentioned three capacities were found to be linear.
Processing and editing of kinetic data of substances for the data and program base system Kindas
Authors: Friedrichs Hans Adolf , Ronkow Leonid Wladimirowitsch
Published: December 2016

On the basis of a Dbase system in the programming languages Fortran and Clipper, the data processing system Kindat has been created. With the aid of this system, approx. 120,000 kinetic data of substances have been compiled, approximated and annotated. These data are available to the metallurgical industry both in tabular form or as approximation formulae. Furthermore, the user can apply the Kindat system directly to solve metallurgical problems, or to process and manage own data.
Characterisation of technical surfaces by means of fractal geometry
Authors: Doege Eckart , Laackman Benedikt , Kischnick Bernd
Published: December 2016

Common technical roughness parameters are not able to characterise technical surfaces clearly. Such parameters often have the same value on completely different surfaces. Only the specification of additional parameters may allow a statement about the surface character. Considering the Weierstraß‐Mandelbrot function a fractal model for the characterisation of surface profiles has been developed. One needs only two parameters to distinguish different surfaces. Thereby a surface profile is measured by means of a surface analyser. Then the fractal parameters will be determined from the data set of a measured profile. To find the suitable fractal description for a given surface the power spectra of the function and of the empirical data are used. Next the empirical power spectrum is interpreted as the power spectrum of a Weierstraß‐Mandelbrot fractal function with fractal parameters to be determined. Additionally this technique also allows the qualitative reconstruction of a previously measured profile.

Series of measurements using the materials X4CrNi 18–10, St12O3 (DC01) and AIMg3 proved the model to be well applicable to sheet surfaces. The fractal parameters are more suitable to classify the surface character than the common technical roughness parameters. The next investigations will be carried out in order to verify the influence of parameters relevant for sheet metal forming (e. g. strain, contact pressure, drawing speed) on the fractal model. The whole work aims at the preparation of a law that describes the local influence of the surface character on the frictional behaviour of sheet metal forming processes. This will be prepared for the use in combination with the method of finite elements (FEM).
Thermodynamic data of the formation of titanium nitride in iron
Authors: Kunze Joachim , Beyer Bodo , Oswald Steffen , Gruner Wolfgang
Published: December 2016

The solubility of titanium nitride in liquid iron is described by the solubility product log([%Ti][%N])1 = −17040/T + 6.40 reported by Turkdogan. The solubility in δ ferrite measured by Kunze is log<[%Ti][%N])δ = −17205/T + 5.56. Combining the solubilities in both phases and the solubilities of nitrogen the distribution equilibrium of titanium can be derived. It is characterized by the thermodynamic distribution coefficient kδ/Io,Ti = [%Ti]δ/[%Ti] = 0.40. By zone melting and secondary ion mass spectrometry of the titanium distribution kδ/ITi = 0.53 was measured. An analysis of all known data led to kδ/Io,Ti = 0.40…0.50.

Measurements of the TiN solubility in austenite by heat treatment were not significant. They led to distribution coefficients between 0.07 and > 1. By zone melting in a carburizing atmosphere a distribution coefficient kγ/ITi = 0.12 was measured. From a thermodynamic analysis performed by Ohtani et al., from the TiN solubility in the melt, and from the solubilities of nitrogen kγ/Io,Ti = 0.13 was deduced. Basing on the distribution equilibria of titanium and nitrogen and on the measured temperature dependence the solubility product log([%Ti][%N])γ = −15000/T + 4.06 was obtained.
Application of new techniques for characterization of non‐metallic inclusions in steel
Authors: Wanibe Yoshimoto , Itoh Takashi , Umezawa Kazushige , Nagahama Hiroshi , Nuri Yoshio
Published: December 2016

This research, aiming at a new approach to the characterization of non‐metallic inclusions in steel, has revealed how to measure and specify them quantitatively. Inclusions to be measured are the ones near the surface or the center of continuously cast low carbon steel, and also those in two sorts of bearing steel after rolling. The specimens are prepared for microscopic observation of the sectioned inclusions, and SEM observation of the inclusions floating up on the surfaces after electron beam remelting of the specimens. Two new methods, which have been proposed in consideration of not only the particle sizes but also the shapes, are applied for the measurement. For the low carbon steel, the inclusions, as a whole or as limited only to alumina, are larger and more spherical in the central zone than those in the surface‐near areas. Morphological differences between the inclusions in these bearing steels can be statistically clarified. The new approach shows that even the overlapping information can be individually separated and quantified by using approximate functions through the suitable choice of variable conversion. Examination and discussion on the present quantitative results can be enriched with various combinations of the specimens and the methods. The achievement can also suggest several remarks for further investigation on inclusions.
Aluminum deoxidation equilibrium in liquid Ni‐Fe alloys equilibrated with CaO‐Al2O3 slags
Authors: Cho Sung‐Wook , Suito Hideaki
Published: December 2016

The deoxidation equilibrium for Al in Ni‐Fe alloys was studied in the equilibrium experiments between CaO‐Al2O3 slags 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.
Effect of sulfur on the stability of cementite
Authors: Grabke Hans Jürgen , Müller‐Lorenz Else Marie
Published: December 2016

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/H2 ratios 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.
Modelling of air ingress and pressure distribution in ladle shroud system for continuous casting of steel
Authors: Wang Laihua , Lee Hae‐Geon , Hayes Peter
Published: December 2016

The pressure distribution and fluid flow profiles whithin the slide gate and shroud nozzle for the continuous casting of steel have been investigated using a full scale water model and a CFD (computational fluid dynamics) model. The water modelling has shown that a large quantity of air can be drawn into the liquid stream if there is any breakdown of the seals in the vicinity of the slide gate. The 3‐dimensional numerical solution for highly turbulent flow has predicted the pressure distribution and velocity profile within the slide gate and shroud. Based on the experimental and numerical modelling, it has been shown that cavitation can occur near the slide gate during ladle teeming. This can be a source for erosion of the refractories. Improvements to the design of the ladle shroud system are recommended.
Study of fluid flow in tundishes due to different types of inlet streams
Authors: Singh Sarbjit , Koria Satish C.
Published: December 2016

Flow pattern and residence time distribution induced by different methods of pouring of molten steel into a tundish are studied by means of a water model with and without flow modifiers (FM). It was found that the submerged stream without FMs produces short circuiting and argon shrouded stream leads to excessive surface directed flow of liquid in a tundish. Open stream pouring generates surface turbulence and does not produce short circuiting. The effect of FM is found to be different for different methods of pouring, e.g. dam eliminates short circuiting and produces surface directed flow for submerged stream, whereas weir limits the surface turbulence within the inlet region for open stream pouring. Dam is found to reduce the dead volume for argon shrouded pouring.
Mixing enthalpies of liquid iron with Vb and VIb elements
Authors: Frohberg Martin G. , Schaefers Klaus , Kuppermann Gunnar
Published: December 2016

By means of a comprehensive literature review and own experiments carried out by levitation alloying calorimetry the mixing enthalpies of liquid iron with Vb and VIb elements were presented. The experimental data were interpreted and analytically represented by different mixing models.
Modelling of microstructural evolution during accelerated cooling of hot strip on the runout table
Authors: Prasad Arun , Jha Sudhakar , Mishra Nirmalendu S.
Published: December 2016

Microstructural evolution in the hot strip after finishing and subsequent accelerated cooling on the runout table has been modelled in order to assess their suitability for further processing. Transient heat transfer and kinetics of phase change comprising austenite to ferrite plus pearlite have been coupled to ascertain temperature profile, taking into accout the heat generated during phase change. Johnson‐Mehl‐Avrami relation together with Scheil's rule of additivity have been invoked. Several process parameters such as, coefficient of heat transfer, temperature at the exit of finishing stand, thickness and the speed of strip have been varied to determine their influence on the extent of phases engendered on the runout table. It has been demonstrated that greater spreadout in cooling arrangement with relatively lower heat transfer coefficient ensures homogeneity in microstructure. Cooling from comparatively higher finishing temperatures may result in greater microstructural uniformity. Two grades of steel – namely 0.05C‐0.23Mn‐0.015Si and 0.08C‐0.37Mn‐0.06Si – were chosen to carry out plant trials to validate the model. Special features of the microstructure have been brought out and the mechanical properties have been correlated.
Prestressing of compression springs
Authors: Knap Fryderyk , Pilarczyk Jan W.
Published: December 2016

A scheme of force variation during the compression of a spring in both elastic and elastic‐plastic state is presented. For the elastic state it has been found that equivalent load increments occur with equivalent deflection increments. In the elastic‐plastic state equivalent load increments correspond to higher deflection increments. Prestressing the spring increases the range of the elastic deformation of a spring. Equations for the determination of torsional moment during prestressing and relationships of total non‐dilatational strain versus elastic strain and radii of elastic zone are also presented. The effect of characteristic spring dimensions and non‐dilatational strain on spring deflection has been determined. A nomogram for the determination of the resultant equivalent strain as a function of external load, also considering residual stress distribution, has as well been elaborated.
Hot direct rolling in ferrite region in extra low‐carbon steel
Authors: Chang Sam K. , Kang Hee J.
Published: December 2016

For the first time, hot direct rolling was applied in ferrite region in the mill and the resulting quality of the cold rolled and annealed sheet steel was as good as that hot direct rolled in austenite region with respect to microstructure and mechanical properties. In case of ferrite phase rolling, microstructure of the hot strip reveals abnormal grains and deformation bands in the grains, and elongation and r value are not so good as those rolled in the austenite phase. However, these abnormal grains left no traces and appeared to be equiaxed grains like the austenite phase rolled microstructure after 75 % cold rolling and continuous annealing at 830°C. This is attributed to the deformation bands which provide nucleation sites for recrystallization during annealing so that recrystallization occurs uniformly in the matrix. (111) texture was well developed and r value thus appeared high.
New method for simultaneous measurement of viscosity, density and surface tension of metallic melts at high temperatures
Authors: Friedrichs Hans A. , Ronkow Leonid W. , Vermot Philippe , Bliznjukow Sergej A.
Published: December 2016

A new method for determination of the viscosity of metallic melts based on the measurement of the velocity of gas bubbles in the melt, is developed. Gas bubbles are produced at known depth through a capillary tube. The time needed by the bubble to reach the surface of the melt is measured with the help of a laser beam. The method is tested with reference metals (Sn, Pb, Cu). The results show that there is a large dependence of the bubble velocity on the viscosity although the diameter of the bubbles is large. The recorded pressure curve in the capillary tube during the bubble formation allows the measurement of the surface tension and the density of the metallic melt to be determined by using the method of the maximum bubble pressure.
On‐line model of gas distribution in the blast furnace
Authors: Nikus Mats , Saxén Henrik
Published: December 2016

In this paper a model for on‐line estimation of the radial gas distribution in blast furnaces is presented. The model is based on molar and energy flow balances for the blast furnace top, using the top gas temperature and gas temperature measurements from a fixed above‐burden probe. The radial distribution of the gas flux in the upper shaft is estimated by means of a Kaiman filter. Using measurement data from a Finnish blast furnace, the method is illustrated to capture short‐term dynamics and to detect sudden (larger) changes in the gas distribution.
Mathematical model for post combustion in smelting reduction
Authors: Becker‐Lemgau Ullrich , Tacke Karl‐Hermann
Published: December 2016

Post combustion in the top space of iron bath smelting reduction furnaces is analysed with three‐dimensional mathematical modelling. Momentum transport and continuity equations in combination with a k‐ɛ model of turbulence are numerically solved for the gas flow field. Combustion reactions are modelled by a set of transport equations based on the SCRS combustion model and its extension to the k‐ɛ‐g model. A two‐stage combustion scheme is formulated to include carbon transfer and combustion. Heat transfer to bath and droplets is approximated including radiation. Computation results for rectangular reactors are presented with velocity patterns and combustion fields. The complex shapes of post combustion flames are demonstrated. Process parameters are varied to study their influence on combustion and heat transfer to the bath. Effects of the injection geometry are illustrated.
Influence of carbon, silicon and molybdenum on the separating and emulsifying behaviour of steel and slag
Authors: Gammal Tarek El , Schrinner Hans‐Jörg , Wosch Erwin
Published: December 2016

The influence of C, Si, and Mo on the surface tension of Armco iron, and on the interfacial tension between Armco iron and a 40%CaO/40%SiO2/20%Al2O3 slag at 1550°C has been investigated. Surface tension was determined according to the drop weight method, and the interfacial tension by the drop detachment method. Based on these measurements, ternary interfacial tension diagrams are set up, which enable the separating and emulsifying tendencies of the related steel/slag/gas systems to be predicted. This is followed by the calculation of the meniscus radius as a function of interfacial tension in continuous casting, together with the assessment of its effect on lubrication.
Applicability of fractal concepts to surface roughness
Authors: Pawelski Hartmut
Published: December 2016

The stochastic part of metal surface profiles can be described by means of fractal geometry. The scaling behaviour of the roughness‐depth as function of the basis length is related to the non‐integral fractal dimension. Regular fractals, which are constructed similarly to the Koch‐curve, are not capable of reproducing typical roughness‐depth distributions. More adequate is the Weierstraß‐Mandelbrot function. If the bearing area ratio approximately follows a power law, the parameters can be easily determined from the exponent and the form of the roughness‐depth distribution, as is shown for a technical surface after cold‐rolling. If the Weierstraß‐Mandelbrot function is used in two classical friction models, the influence of the parameters including the fractal dimension on the friction coefficient in the case of dry surfaces can qualitatively be estimated.
A model for description of structure forming processes during reheating steels for thermal treatment
Authors: Jurdeczka Uwe , Peisker Dieter
Published: December 2016

Modern production technologies, applied for parts or billets of steels for heat treatment, demand a possibility to predict the resulting and important structure parameters. The description of the austenite structure before transformation is also interesting for technologies with austenite transformation. A concept is presented to model austenitizing, including austenite nucleation, austenite nuclei growth and austenite grain growth. Monte‐Carlo‐Simulation is the mathematical method for modelling. The influence of secondary phases, especially the dissolution, is taken into account by using an additional part of the model. The mathematical method therefore is finite‐differences. Based on this concept, a model is developed for description of austenization during reheating. The variables for input are estimated at metallografical plane. Tests were carried out with case hardening steels and tempering steels. Austenite nuclide density and grain growth behaviour were estimated, both according to the initial state.
Finite element modelling of the creep deformation of T91 steel weldments at 600°C
Authors: Bhaduri Arun Kumar , Gaudig Wolfgang , Theofel Heinrich , Maile Karl
Published: December 2016

Finite element modelling of the creep deformation of T91 steel weldments, welded using the manual metal arc (MMA) and submerged arc (SA) welding processes, was carried out to predict creep curves for both of the weldments under different stresses and compared with the experimental data. The stress and strain redistribution across the length of the transverse‐weld specimens has also been predicted. Data of creep tests at 600°C at stresses between 90‐130 MPa for the base metal, the MMA and SA weld metals, and the simulated heat‐affected zone were used to determine Garofalo's equation for creep strain. Finite element meshes for both of the weldments were constructed after calculating the HAZ locations using Rosenthal's heat flow equation.
Dust formation in a BOF converter
Authors: Nedar Lotta
Published: December 2016

Minimisation of waste and manipulation of residues to suit succeeding processes today is one of the steel works most important research areas. BOF dust is expensive to depose in landfills and difficult to recycle due to its zinc contents. The simultaneous loss of raw materials and cost increase makes it important to minimise the generation of dust. This can be done by employing better process control systems with regard to the mechanisms governing the generation. Four dust forming mechanisms can be considered in a converter: ejection of metal, ejection of slag, entrainment of charged material and vaporisation.

In order to determine the importance of the four dust forming mechanisms and to characterise dust, with special emphasis to zinc, the off‐gas from a 100‐t BOF was sampled during twenty seven heats. The sampling equipment allows the sampling of both solid dust particles and vaporised elements. Samples from the first and the second part of blowing show significant differences both in chemical composition and in the origin of formation. The major dust formation mechanism is the ejection of metal and slag, respectively. Entrainment of solids plays an important role only during the first part of blowing. Vaporisation of elements from the bath is most important during the end of blowing. The formation of dust is influenced by process operation control, especially lance position, silica contents and time of charging of slag formers. Zinc is mostly found on the rim of ejected particles where a gradual transition of zinc oxide to zinc ferrite to iron oxide is found. At sampling temperatures of between 800 and 1000°C most of the zinc had already condensed.
Transformation behaviour of the high temperature martensitic steels with 8 – 14% chromium
Authors: Finkler Helmut , Schirra Manfred
Published: December 2016

Comprehensive development work on martensitic steels belonging to the so‐called 12% Cr steel group were performed at the Institute for Materials Research (IMF) of Forschungszentrum Karlsruhe on martensitic steels, the so‐called 12% Cr steel group, in order to meet the various requirements in nuclear and conventional energy technology. The transformation characteristics of 29 different grades of steel and 38 heats have been determined and continuous cooling transformation (CCT) diagrams have been prepared. The diagrams are first described by groups of subjects in a chronological order because the change in the chemical composition cannot be correlated in all cases with the change in transformation behaviour.

The quenching hardness can be satisfactorily described as a function of the C+N content if, taking into account the Nb, Zr, Ta, Hf fractions, a common effectiveness factor is calculated. This effectiveness factor is also integrated in the calculation of the Ms point by modifying accordingly the equation proposed by Steven and Haynes for low‐alloy steels and supplemented by the summands for V and W. An equation is introduced for the calculation of the critical cooling rate for pearlite transformation which takes into account the special influence exerted by elements Cr, V, Mo, W, Ge. The comparison between calculated and measured values for Ms and Vcrit is satisfactory, except for some steels.
Carbon or nitrogen alloyed quenched and tempered stainless steels ‐ a comparative study
Authors: Berns Hans , Ehrhardt Rüdiger
Published: December 2016

Some conventional stainless quenched and tempered steel grades were modified by substituting nitrogen for carbon and by variing the contents of chromium, molybdenum and nickel. Results of a comparative study of carbon and nitrogen steels are presented in a wide range of tempering temperatures.

In nickelmartensitic steels nickel can be partially substituted by nitrogen without harming the properties. Due to their finer microstructure nitrogen steels with 15‐17 %Cr, 2 %Ni and 0.2 %N, at the same strength level, offer higher toughness and better corrosion resistance than the respective conventional steel X20 CrNi 17 2.
Effects of medium‐ and low‐temperature carbides on the mechanical properties of a low‐carbon steel
Authors: Zhu Aiwu , Meyr Andreas , Pink Erwin
Published: December 2016

A steel with low mass contents of carbon (0.04 %) was quenched and aged at temperatures between 60 and 200°C. The increase in yield stress due to these aging treatments and other mechanical properties were analyzed. A rather direct correlation of results from internal friction with those for yielding exists. The precipitates which form during aging at the lowest temperatures are equally capable of improving the yield stress. Thus it is possible to improve the properties by modified “bake‐hardening”. Comparisons with literature confirmed that the aging procedures influence the kinetics of precipitation and the resulting strength increase: intermediate aging at room temperature before the proper aging treatment are of advantage.
Fatigue crack propagation near fatigue threshold in various structural steels
Authors: Han Seungho , Reinhold Patrick , Ring Markus , Dahl Winfried
Published: December 2016

The investigations have been conducted by measuring fatigue crack propagation near fatigue threshold in various structural steels differing in chemical composition and strength level. The fatigue crack propagation measurements were carried out using the constant‐load‐amplitude test in Paris‐region, R‐constant and Kmax‐constant method in near fatigue threshold region. Scanning electron microscopy at fatigue crack front on fracture surface was applied to interpret the influence of crack closure effects on the measured fatigue threshold. Marked fretting oxide deposits distributed on the fracture surface at threshold level were observed in a low load ratio resulting from the combined action of plasticity‐ and oxide‐induced crack closure under laboratory atmosphere. Fatigue threshold dependent on the load ratio appeared to be related to the extent of the crack closure effect. By considering the relationship of reversed plastic zone size and grain size the fatigue threshold in region of crack closure was calculated theoretically. The result has shown a good agreement with the experimentally measured values.
Dynamic fracture behaviour of simulated weld heat affected zone of a high strength low alloy steel
Authors: Lei Wei‐Sheng , Su Yan , Yao Mei
Published: December 2016

Fracture toughness properties of a simulated weld coarse grain heat affected zone (CGHAZ) in a newly developed 785 MPa grade high strength low alloy (HSLA) steel were investigated at different loading rates and a series of temperatures. It is indicated that the fracture toughness KIc is a single‐value function of the parameter ΔH=kT In (A/ε̇), implying that just like the plastic deformation, the event of fracture initiation is also controlled by dislocation thermal activation movement.