bluuebunny/crossref_metadata_2025 huggingface dataset:
An Analytical Model for Dependence of Force and Forward Slip on Speed in Cold Rolling
Authors: Pawelski Hartmut
Published: December 2016

An explicit analytical method for determining approximations for roll force and forward slip for strip rolling is introduced. It reproduces all main predictions of classical strip theory, but is completely free of any numerical algorithms. Nevertheless, for extreme cases of cold rolling, like foil or skin pass rolling, more sophisticated algorithms are still needed.

For the friction coefficient in the roll gap and its increase from the entry to the neutral point also explicit relations are proposed. In the framework of this analysis, they are sufficiently precise for cold rolling with one‐phase lubricants and stochastic surfaces. Only a single parameter of adaptation is needed, the microscopic friction coefficient μmicro.

The quality of the total model is illustrated by means of the dependence of roll force and forward slip on railing speed. For this purpose measured process data (four different pass‐schedules, seven to ten coils each) for cold rolling of copper with rolling oil is analyzed.
Investigation of Waste Wood as a Blast Furnace Injectant
Authors: Takekawa M. , Wakimoto K. , Matsu‐ura M. , Hasegawa M. , Iwase M. , McLean A.
Published: December 2016

National legislation within Japan has increased the need for the development of new process technologies that will utilize waste wood materials. In order to generate some fundamental data with respect to the possible injection of such materials into blast furnaces, a study has been made of the decomposition and gasification reactions that take place when biomass material, in this case Japanese cypress chips, are exposed to temperatures between 1673 and 2073K using a high frequency induction furnace. The relative amounts of gas, char and tar were determined as well as the concentration of the various species present in the gas phase. The results obtained from gas analysis were in good agreement with values calculated from thermodynamic equilibria.
Neutron Scattering Study on Precipitation and Recrystallization Behaviours in P‐Free and P‐Alloyed IF‐Steel Sheets
Authors: Shin Eunjoo , Seong Baek‐Seok , Lee Chang‐Hee , Kang Hee‐Jae , Huh Moo‐Young
Published: December 2016

In order to investigate the effect of coiling temperature and alloying of phosphorus (P) on the formation of precipitates and recrystallization behaviour, initial samples of P‐free and P‐alloyed IF‐steels were prepared by coiling at 580 and 720°C. Variations of precipitates and textures after coiling, cold rolling and recrystallization annealing were studied by means of small angle neutron scattering (SANS), neutron texture measurements and TEM observations. Hardness measurements and microstructure observations disclose that both coiling temperature and alloying of P affect softening of cold rolled samples. Coiling at a lower temperature increases the number of fine precipitates smaller than 10 nm in the hot band. Upon recrystallization annealing, precipitates ranging in size from 10 to 50 nm increase at the expense of fine particles smaller than 10 nm. Recrystallization behaviours in cold rolled IF‐steel samples were discussed by tackling the distribution of precipitates and the amount of solute P atoms in solution.
Thermodynamic Activities of “FeO” in some Ternary “FeO”‐Containing Slags
Authors: Fredriksson Patrik , Seetharaman Seshadri
Published: December 2016

Thermodynamic data concerning “FeO”‐containing slags is of importance in ladle refining of steel. With a view to generate a set of reliable and self‐consistent thermodynamic data for these slags, experimental determination of the activities of iron oxide in the Al2O3‐“FeO”‐SiO2, CaO‐“FeO”‐SiO2 and “FeO”‐MgO‐SiO2 systems was carried out using the gas equilibration method involving CO‐CO2‐Ar gas mixtures in the temperature range 1823‐1923 K. The slag samples kept in Pt crucibles were quenched after the equilibration and subjected to chemical analysis. The thermodynamic activities of “FeO” in the slags were calculated from the experimental data. The results are incorporated into a thermodynamic description of silicate melts developed in the present laboratory. The model is based on a Temkin‐Lumsden approach and is able to compute the thermodynamics of higher order systems from the lower order ones. The model was updated with the present results and iso‐activity contours of “FeO” in the three component systems are presented at 1873. The capacity of the model to predict the thermodynamic activites in four‐, five‐, and six‐component slags is demonstrated in the case of steelmaking slags.
Activities of Phosphorus in Copper‐Iron Liquid Alloys Saturated with Copper‐Iron Solid Solutions
Authors: Kaida Y. , Hasegawa M. , Kikuchi Y. , Wakimoto K. , Iwase M.
Published: December 2016

In order to determine the activities of phosphorus and iron in liquid {Cu‐Fe‐P} alloys, the two coexisting phases of liquid {Cu‐Fe‐P} alloys +  solid solutions were brought into equilibrium with a mixture of Al2O3 + AlPO4 + FexAl2O4 at temperatures of 1416K and 1526K. The oxygen partial pressures were measured with the aid of a solid‐oxide galvanic cell of the type:

(+)Mo / Mo + MoO2/ ZrO2(MgO) / {Cu‐Fe‐P} +  +  +  +  / Fe(‐)

The equilibrium reactions underlying the experiments can be expressed by 2[P]cu + (5/2) (O2) +  = 2  and x[Fe]Cu + (1/2) (O2) +  =

The Henrian activity coefficient referred to 1 wt pct solution in pure liquid copper could be well expressed by the formula

log fP° = (4.46±0.40) ‐ (8.67±0.59)/(T/K).

The iron activities referred to pure solid iron could be formulated as log aFe =‐ (0.37 ± 0.12) + (500 ±200) /(T/K).
Microstructural Development of HP9/4/30 Steel During Partial Remelting
Authors: Omar Mohd Z. , Atkinson Helen V. , Palmiere Eric J. , Howe Andrew A. , Kapranos Plato
Published: December 2016

Semi‐solid processing, also known as thixoforming, is a forming process that shapes metal components in their semi‐solid state. Prior to forming, the microstructure of the alloy consists preferably of solid metal spheroids in a liquid matrix. This paper describes the microstructural development within the semi‐solid zone of a typically banded high performance HP9/4/30 steel through a direct partial remelting process from as‐received and as‐deformed conditions. Partial remelting was carried out at temperatures between 1430 and 1470°C. Liquation occurred initially at the grain boundaries, then also along the segregation bands. With increasing time and hold temperature, these “columns” broke down into shorter, more equiaxed segments, offering a better chance of being thixoformed. The microstructures revealed distinct polygonal cells at 1430°C that changed to more rounded solid grains with diminishing sharp edges at 1450°C, followed by smaller truncated cell structures due to the liquation of the bands at 1460°C and 1470°C. The partial remelting procedures carried out in this study are from material that is in a recrystallised state. Thixoforming from this recrystallised state is shown to be successful. This indicates a widening of the range of potential routes to thixoformable microstructures.
Physical Metallurgy of Multi‐Phase Steel for Improved Passenger Car Crash‐Worthiness
Authors: Samek Ludovic , De Cooman Bruno C. , Van Slycken Joost , Verleysen Patricia , Degrieck Joris
Published: December 2016

The dynamic testing of high strength automotive steel grades is of great practical importance if their crash‐worthiness is to be evaluated. During forming operations, steels are processed in a controlled dynamic manner. In collisions, the deformation is different in the sense that the deformation is not controlled, i.e. both strain and strain rate are not pre‐determined. No clear standard testing procedures are currently available to test high strength steels dynamically, in order to evaluate their performance during car crashes. High tensile strength TRIP‐aided steels have been developed by the steel industry because of their promising high strain rate performance. The present contribution focuses on the effect of the strain rate and temperature on the mechanical behaviour of the low alloy high strength TRIP steel. The tests were carried out on the separated phases in order to determine their specific high strain rate deformation response. The temperature‐dependence of the transformation rate of the retained austenite is presented. It is argued that the adiabatic conditions present during high strain rate deformations have a beneficial effect on the behaviour of TRIP steel.
Niobium Carbide Precipitation in Microalloyed Steel
Authors: Klinkenberg Christian , Hulka Klaus , Bleck Wolfgang
Published: December 2016

The precipitation of niobium carbo‐nitrides in the austenite phase, interphase and ferrite phase of microalloyed steel was assessed by a critical literature review and a round table discussion. This work analyses the contribution of niobium carbide precipitates formed in ferrite in the precipitation hardening of commercially hot rolled strip. Thermodynamics and kinetics of niobium carbo‐nitride precipitation as well as the effect of deformation and temperature on the precipitation kinetics are discussed in various examples to determine the amount of niobium in solid solution that will be available for precipitation hardening after thermomechanical rolling in the austenite phase and successive phase transformation.
Anisotropic Distortion of Tool Steels D2 and M3 during Gas Quenching and Tempering
Authors: Wei Jianfei , Kessler Olaf , Hunkel Martin , Hoffmann Franz , Mayr Peter
Published: December 2016

Heat treatment of forged high alloyed tool steels produces anisotropic dimensional change. In the present work, the distortion behaviour of tool steels D2 and M3 during gas quenching and tempering was investigated. The influences of material manufacturing processes including casting, forging and powder metallurgy on anisotropic distortion were investigated. Rectangular samples were quenched in a vacuum furnace with high pressure gas cooling. The sample distortion was measured by a coordinate measuring machine. By means of dilatometry and metallography, the possible mechanism of anisotropic distortion was investigated. Experimental results showed that the distortion of cast and powder metallurgical steels was nearly isotropic because of an isotropic carbide arrangement, but the distortion of ingot cast and forged steels was apparently anisotropic during gas quenching and tempering. The carbide bands are the main cause of anisotropic distortion in the investigated steels. Dilatometric experiments showed that phase transformation plays an important role in the mechanism of anisotropic distortion. First simulations of the dimensional change during quenching indicated that transformation induced plasticity is the main mechanism by which anisotropic distortion occurs in this type of steels.
Iron‐Rich Iron‐Titanium‐Silicon Alloys with Strengthening Intermetallic Laves Phase Precipitates
Authors: Löffler Falk , Palm Martin , Sauthoff Gerhard
Published: December 2016

Two‐phase ternary Fe‐Ti‐Si alloys with Si contents from 2 to 16 at.% and Ti contents from 2 to 28 at.% were studied with respect to room temperature hardness, fracture strain and yield stress at room and higher temperatures up to 1150 °C. In addition oxidation was checked at temperatures between 400 and 1150 °C. The alloys are strengthened by precipitation of the stable Laves phase (Fe,Si)2Ti which is a hard and brittle intermetallic phase. The yield stress as well as the brittle‐to‐ductile transition temperature (BDTT) increase with increasing Ti content. Yield stresses up to about 1400 MPa and BDTT between 100 °C and 600 °C with fracture strains of the order of 1 % below BDTT were achieved. The observed short‐term oxidation performance at temperatures up to 1150 °C compares favourably with that of Fe‐AI alloys with high Al contents.
Feasibility Study of Hydrogen Generator with Molten Slag Granulation
Authors: Akiyama Tomohiro , Mizuochi Toshio , Yagi Jun‐Ichiro , Nogami Hiroshi
Published: December 2016

A huge amount of hot molten oxides, such as steelmaking slag and molten municipal waste, is discharged at present without heat recovery, in spite of its very high potential. For example, hot molten slag as a by‐product in the Japanese steelmaking industry, over 1723 K in temperature, reaches as much as 30 million tonnes annually. To recover heat of the viscous slag chemically, the strongly endothermic reaction CH4+H2O →3H2+CO was selected and then the property of dry granulation of the molten slag by Rotary Cup Atomizer (RCA) for expanding surface area of the slag was experimentally studied. The purpose of this paper was, therefore, to study slag granulation under various conditions for promoting heat exchange between slag and gas, in which the influence of the rotating speed and the shape of the cup on the slag drop size was mainly examined. The collected slag drops were correlated with operating conditions such as rotating speed, cup shape, etc. Most significantly, the molten slag was successfully granulated under the dry conditions without water impingement. The rotating speed of the cup influenced the diameter and shape of the slag drops very strongly. The higher rotating speed made the slag drops smaller, more spherical and uniform. Drops with 5 to 6 mm of average dimension were obtained at a rotating speed of 15 rps (900 rpm), and drops with about 1 mm at 50 rps (3000 rpm). In the former case, the shape of the obtained drops changed from spherical to ribbon‐like. These results will be useful to establish new heat recovery processes with hydrogen generation from molten slag with many benefits. Energy analysis and cost evaluation were also conducted, to study the benefit of the proposed process.
Metallurgical Aspects of Ultra Fast Cooling in front of the Down‐Coiler
Authors: Lucas Aurélie , Simon Pierre , Bourdon Guillaume , Herman Jean‐Claude , Riche Philippe , Neutjens Joeri , Harlet Philippe
Published: December 2016

The Ultra Fast Cooling technology developed by CRM has been implemented on the hot strip mill of Carlam (Arcelor group), just in front of the down‐coilers (late UFC). The results have demonstrated the controllability of the system and the great efficiency (≥ 3.5 MWm−2, 300°C/s on 4 mm thick strip) of the cooling unit. Increasing the cooling rate in a controllable way makes the production of high strength steels easier and cheaper. The combination of laminar and UFC technologies opens the way for new cooling schedules. Multiphase microstructures are therefore easily generated by controlling the intermediate temperature ‐ between laminar cooling and UFC ‐ and the coiling temperature.
Influence of Precipitates Size and Distribution on Room Temperature Mechanical Properties and Accelerated Creep of X20CrMoV121
Authors: Skobir Danijela A. , Vodopivec Franc , Kosec Ladislav , Jenko Monika , Vojvodič‐Tuma Jelena
Published: December 2016

The effect of microstructure on creep resistance of the low carbon chromium steel X20CrMoV121 after 100‐hours of static‐load test at a temperature of 580 °C and constant stress of 170 MPa was investigated. The specimens for the experiments were extracted from steam pipes of a steam power plant and heat treated. The effect of isothermal annealing on the microstructure and hardness as well as the kinetics of the precipitation of the carbide particles were determined.
Thermodynamic Activities of “FeO” in some Binary “FeO”‐Containing Slags
Authors: Fredriksson Patrik , Seetharaman Seshadri
Published: December 2016

In the present investigation, experimental measurements of the thermodynamic activities of iron oxide in the Al2O3‐“FeO”, CaO‐“FeO” and “FeO”‐SiO2 systems were performed in the temperature range 1823‐1873 K by using gas equilibration technique. The molten slag, kept in a Pt‐crucible was brought to equilibrium with a gas mixture of known oxygen partial pressure. A part of the Fe from the “FeO” was reduced during the equilibration and got dissolved in the Pt phase. The samples were quenched after the required equilibration time and the slag phase as well as the platinum crucible was subjected to chemical analysis. The activities of “FeO” in the slag were calculated from the experimental data using thermodynamic information on the Fe‐Pt binary metallic system generated and assessed earlier. The experimental results are compared with earlier thermodynamic studies of the slag systems. Reassessment with the KTH slag model is performed and the results are compared with other thermodynamic models, viz. F*A*C*T™ and Thermo‐Calc™ respectively. The experimental activities predicted by the KTH slag model are in good agreement with the experimental data available in the literature. A general agreement between the various models is also observed.
A Study of Some Elemental Distributions Between Slag and Hot Metal During Tapping of the Blast Furnace
Authors: Andersson Annika J. , Margareta T. Andersson A. , Jönsson Pär G.
Published: December 2016

This paper investigates the distribution of elements between slag and hot metal from a blast furnace through calculation of distribution coefficients from actual production data. First, samples of slag and hot metal tapped from a commercial blast furnace were taken continually at 10‐minute intervals for a production period of 68 hours. Distribution coefficients of manganese, silicon, sulphur and vanadium were then calculated from the results of the sample analyses.

A major conclusion drawn from examination of the results was that the behaviour of the studied elements was as could be expected when approaching the equilibrium reactions from thermodynamic theory. The distributions of the elements in the slag‐metal system showed clear tendencies which did not appear to be influenced by the operational conditions of the furnace. For example, for manganese, vanadium and sulphur, it was found that a higher basicity led to a decreased distribution coefficient LMnand LV, but an increased LS, which is according to theory. Another observed relationship was that slag basicity increased with an increased carbon content in the hot metal, which indicated that SiO2was reduced to [Si] when the oxygen potential decreased. Furthermore, it was found that sulphur and silica behaviour likened that of acidic slag components, while the manganese oxide and vanadium oxide behaviour was similar to that of basic slag components.
Laser‐Aided Flow Curve Determination in Hydraulic Bulging
Authors: Bleck Wolfgang , Blumbach Michael
Published: December 2016

Hydraulic bulging can be used to characterise sheet material under biaxial stress conditions. A new measuring method applying laser light section for geometry analysis and a camera device for local strain determination enables a continuous on‐line calculation of flow curves. Effective stress and equivalent strain can be recorded until the failure of the material, thus providing extended information compared to the tensile test. The testing procedure is predestined for simulation purposes and for an application in the quality control sector, allowing for a quick and profound material characterisation.

This work presents flow curves, strain hardening curves, and strain paths of several steel grades and one aluminium alloy. Some selected materials were also investigated with regard to different yield criteria and results from the tensile test.
A New Forming Strategy to Realise Parts Designed for Deep‐drawing by Incremental CNC Sheet Forming
Authors: Hirt Gerhard , Ames Jochen , Bambach Markus
Published: December 2016

The work detailed in this paper focuses on a new forming strategy for the CNC incremental sheet forming (ISF) process that is appropriate to form steep flanges, e.g. for parts designed for deep‐drawing. When parts are designed for deep‐drawing, they usually contain steep or rectangular side walls that cannot be manufactured using the standard ISF strategies. Unlike prior approaches to obtain steep flanges through ISF, the present method achieves a rough approximation to the final part already in the preforming stage. This can be accomplished without excessive sheet thinning due to sheet bending and stretching at this stage. As a consequence, additional material can be used for the finishing stages, thus yielding a final part with largely reduced thinning. After basic studies on a simple benchmark problem, the new bending/stretching strategy is tested with an industrially applied part that is usually produced by deep‐drawing. Finally, the ISF workpiece is evaluated against the deep‐drawn component with respect to sheet thickness and geometric accuracy.
Development of a Robot‐Based Sheet Metal Forming Process
Authors: Meier Horst , Dewald Oliver , Zhang Jian
Published: December 2016

This paper describes a new sheet metal forming process for the production of sheet components for prototypes and small lot sizes. The generation of the shape is based on kinematics and is implemented by means of a new forming machine consisting of two industrial robots. Compared to conventional sheet metal forming machines, this newly developed forming process offers a high geometrical form flexibility, and comparatively small deformation forces enable high deformation degrees. The principle of the procedure is based on flexible shaping by means of a freely programmable path‐synchronous movement of the two robots. The final shape is produced by the incremental infeed of the forming tool in depth direction and its movement along the contour in lateral direction at each level of the depth direction. The supporting tool with its simple geometry is used to support the sheet metal and follows the forming tool at the rear side of the sheet metal. The sheet metal components manufactured in first attempts are of simple geometry like frustum and frustum of pyramids as well as spherical cups. Among other things the forming results are improved by an adjustment of the movement strategy, a variation of individual process parameters and geometric modifications of the tools. In addition to a measurement of the form deviations of the sheet with a Coordinate Measurement Machine, screened and deformed sheets are used for deformation analyses. Furthermore, the incremental forming process is analysed with assistance of the finite element method. In total the results show that a robot‐based sheet metal forming with kinematic shape generation is possible and leads to acceptable forming results. In order to be able to use the potential of this process, a goal‐oriented process design is as necessary as specific process knowledge. In order to achieve process stability and safety, the essential process parameters and the process boundaries have to be determined.
Deep Drawing of Friction Stir Welded Thin Sheet Aluminium Steel Tailored Hybrids
Authors: Merklein Marion , Giera Artur , Geiger Manfred
Published: December 2016

Friction stir welding undergoes a steep evolution in industrial applications since the invention in the early 1990s. Especially for aluminium alloys in sheet thicknesses over 2 mm a lot of applications are established, whereas a lack in knowledge about friction stir welding of thin sheets with sheet thickness less than 2 mm exists. This article deals with friction stir welding of thin sheet aluminium steel tailored hybrids and their formability. These investigations tend to close the gap of availability of friction stir welded blanks in the range of 1 mm sheet thickness and to offer new applications of this joining technology. For production of aluminium steel tailored hybrids AA5182 with a thickness of 1.2 mm and DC04 in 1.0 mm are used, the joining partners are friction stir welded in a lap joint. Different tool geometries and process parameters are performed to achieve the highest strength and elongation at fracture of the tailored hybrids. The influence of the stirring on the arrangement and distribution of both materials in the welding zone and its microstructure is analysed using light optical and scanning electron microscopy. In addition to tensile tests planar microhardness measurements help to detect the local changes of the mechanical properties in the characteristic zones of the weld seam. Tailored hybrids, which were friction stir welded with the best welding parameters in accordance to the mechanical properties of the weld seams, were used for deep drawing tests of friction stir welded thin sheet aluminium steel tailored hybrids. The maximum drawing ratio of these tailored hybrids coincides with the one of the parent material of AA5182.
An Assessment of the Machinability of Iron‐Rich Iron‐Aluminium Alloys
Authors: Denkena Berend , Tönshoff Hans Kurt , Boehnke David
Published: December 2016

Iron‐Aluminium‐Alloys show high potential as a material for automotive and aerospace applications due to their combination of properties. In comparison with other iron‐based alloys the lower density and good mechanical properties lead to a higher specific strength, which makes them interesting for lightweight applications. These alloys also have a good to outstanding resistance to oxidation and sulfidation. Nevertheless their use is restricted because of limited knowledge regarding the machining of these materials. New tool and cutting technologies have to be developed to counteract this situation. For example, a successful industrial introduction of a 10 wt% Al iron‐aluminium alloy would require a cutting tool lifetime 10 to 100 times higher than the currently achievable. For this purpose, the characteristic wear effects at the cutting edge have to be understood and the alternating changes of chip formation by constant process parameters have to be explained. Reasons and remedies are discussed.
The Effect of Carbon in Slag on Steel Reoxidation by CaO‐SiO2‐Al2O3‐MgO‐MnO‐FetO Slags
Authors: Suk Min‐Oh , Jo Sung‐Koo , Seo Chang‐Woo , Kim Seon‐Hyo , Kim Jeong‐Sik , Shim Sang‐Chul , Kim Jeong‐Tae
Published: December 2016

An equilibrium study was carried out at 1873K to ascertain the effect of carbon in CaO‐SiO2‐Al2O3‐MgO‐MnO‐FetO slag systems on their FetO and MnO activity coefficients, representing the slags’ thermodynamic potential for steel reoxidation. Both γfeto and γmno showed not only a sharp increment but also a simultaneous slow decrement by increasing carbon content in slag, suggesting opposite roles of the carbon according to its stable forms. XPS (X‐ray photoelectron spectroscopy) was introduced to clarify the stable forms of carbon in slag. XPS results prove that carbon dissolves in slag as carbonate, and carbide ions under oxidizing and reducing atmospheres, respectively. It was concluded that carbonate ions increase γfeto and γmno, but that carbide decreases them. This paper suggests an application method of the present results to actual ladle refining processes, in order to enhance steel cleanliness with maintaining (FetO + MnO) in slag to some allowable amount.
A Study on the Buckling Behaviour of Strips and Plates with Residual Stresses
Authors: Fischer Franz Dieter , Friedl Nikolaus , Noé Andreas , Rammerstorfer Franz G.
Published: December 2016

During and after rolling or flattening of metal strips and plates the permissible deviations from flatness are described by the permissible absolute wave height and the flatness index. Both values can be determined on a measuring table while the material is not subjected to global tension. Because this procedure is expensive, time‐consuming and allows measurement only at discrete positions along the strip length, on‐line flatness measuring systems are used which can detect the distribution of longitudinal tensile stresses distributed across the strip width allowing for the calculation of the flatness index. This value does not always agree with the value obtained directly by measuring on the table even when the measurement of the longitudinal tensile stress distribution operates perfectly. It can be shown that the measurement of the tensile stress distribution does not give a direct indication on the wave height in the tension‐free state determined on the measuring table.

To explain the relationship between tensile stress distribution in the strip and the flatness measurement on the measuring table, the buckling behavior is analysed both with and without dead load for simple symmetrical residual stress distributions resulting, e.g., from the rolling process. Based on the knowledge of the distribution of the longitudinal residual stresses across the strip width, the flatness index and the wave height can be determined by using a specialized finite element model. If the direct measurement is performed under action of dead load, large differences between the directly and indirectly obtained flatness index are observed. Below a certain limit of the intensity of the residual stress distribution the strips and plates lie flat on the measuring table. Above this limit the strip lying on the table exhibits post‐bucking deformations. In the latter case, the wave height increases with strip thickness and intensity of residual stresses.
Reduction of Fine Ores in Argon‐Hydrogen Plasma
Authors: Plaul Jan Friedemann , Krieger Wilfried , Bäck Eduard
Published: December 2016

The steel industry is a major source of global CO2 emission. Larger reductions of greenhouse gases are the challenge to develop new processes, like Hydrogen Plasma Smelting Reduction (HPSR). The present paper shows physical and chemical fundamentals for the reduction of iron oxides with hydrogen plasma. The behaviour of different hematite iron ores during melting and reduction with hydrogen plasma were investigated with thermogravimetry and a laboratory plasma furnace. The path of iron oxides during smelting and reduction in the Fe‐O phase diagram are described. Reduction tests in the laboratory furnace show the possibility to reduce hematite iron ores with hydrogen plasma in a short time with high utilization degrees without direct CO2 emissions.
New Methods for In‐Situ Determination of Iron Oxide in Steelmaking Slags
Authors: Schwerdtfeger Klaus
Published: December 2016

Although iron oxide is the most important component of steelmaking slags, no reliable technique for its in‐situ determination has been established yet. This paper however, presents data on the effect of iron oxide on the electrical conductivity of CaO‐SiO2‐FeO‐Fe2O3 melts, and on limiting current and impedance in direct current or alternating current charge transfer at iron electrodes. The strong influence of iron oxide content can be utilized for in‐situ determination of total iron oxide content and Fe3+/Fe2+ ratio. The possible probe designs are presented and the principles and procedures of the measurement are explained.
The Nitrogen Solubility in Molten Stainless Steel
Authors: Jiang Zhouhua , Li Huabing , Chen Zhaoping , Huang Zongze , Zou Deling , Liang Lianke
Published: December 2016

Nitrogen solubility in the austenitic stainless steel melts was measured in the laboratory by bubbling nitrogen gas under different partial pressures of nitrogen and temperatures. A new thermodynamic model for the calculation of nitrogen solubility in molten stainless steel in a wide range of alloy concentrations, temperatures, and pressures has been successfully established by introducing a new term for the effect of pressure on the nitrogen activity coefficient. The calculation results were in good agreement with the measured values. The influences of temperature, nitrogen partial pressure and chemical composition on the nitrogen solubility in molten stainless steel are discussed based on the calculated results. It is possible to produce high nitrogen steels at normal pressure by optimizing the design of the alloy composition and controlling the lowest melting temperature from a thermodynamic point of view.
A Mathematical Model of a Blast Furnace Injection Tuyere
Authors: Hellberg Per , Jonsson T. Lage I. , Jönsson Pär G.
Published: December 2016

One way to further utilise produced gases in an integrated metallurgical plant is to replace oil with gas as a reducing agent in a modern blast furnace. Accordingly, it is of great interest to study the injection of reducing gas into the blast furnace. Therefore, a three‐dimensional mathematical model has been developed which simulates the injection of the gas by lances into the tuyere. The model includes the coupled solution of the flow field and the chemical reaction of the gases in the tuyere. Two different types of fuel gas, coke oven gas (COG) and basic oxygen furnace gas (BOF) have been modelled using one injection lance. The modelling technique is presented and discussed as well as the implied results. Furthermore, process parameters such as different gas compositions etc. are investigated using the developed model. Not surprisingly, the main results show that the COG is combusted more completely than BOF gas, which leads to higher flame temperature of the blast putting demand forward to lower the heat load of the tuyere. However, the modelling of the raceway is as far not included in the model, hence the influence of the outlet boundary condition at the tuyere is not reflected in the presented results.
Mathematical Modelling of Molten Steel Flow Process in a Whole RH Degasser during the Vacuum Circulation Refining Process: Mathematical Model of the Flow
Authors: Wei Ji‐He , Hu Han‐Tao
Published: December 2016

A three‐dimensional mathematical model for the molten steel flow in a degasser during the RH refining process has been proposed and developed. The physical characteristics of the process, particularly the behaviour of gas‐liquid two‐phase flow in the up‐snorkel and the momentum exchange between the two phases are considered. The ladle, snorkels and vacuum vessel are regarded as a whole in the model, and the gas‐liquid two‐phase flow is treated and described on the basis of the two‐fluid model and using the especially modified two‐equation κ‐∊ model. The details of the model are presented.
A Physical Model Study of Swirl Phenomena in a Top Blown Bath
Authors: Nordquist Annie , Iguchi Manabu , Yokoya Shinichiro , Jonsson Lage , Jönsson Pär
Published: December 2016

The present study is focused on swirl motion in a top blown water model, where a deep water swirl motion is observed. During the experiments, the top lance, with cylindrical nozzles, was placed above the water surface and thereby produced an external force on the bath. The effect on how different parameters, such as nozzle diameter and the distance between the bath surface and nozzle exit, i.e. the lance height, affect the swirl motion were studied. More specifically, the amplitude and period of the swirl as well as the starting and damping time of the swirl were determined. The amplitude was found to increase with an increased nozzle diameter and gas flow, while the period had a constant value of about 0.5 s for all nozzle diameters, gas flows and lance heights. The starting time for the swirl motion was found to decrease with an increased gas flow, while the damping time was found to be independent of gas flow rate, nozzle diameter, lance height and ratio of depth to diameter.
Modelling of Manganese Sulphide Formation during Solidification, Part II: Correlation of Solidification and MnS Formation
Authors: Diederichs Roman , Bülte Raimund , Pariser Gerhard , Bleck Wolfgang
Published: December 2016

The high temperature properties of steels depend on the solidification parameters and the formation parameters of manganese sulphide precipitates. Therefore, the occurrence of MnS precipitations in relation to primary and secondary microstructures was studied for different steel grades with a primary delta‐ferritic solidification or a primary austenitic solidification. The liquidus and solidus temperatures as well as the δ‐γ‐transformation temperature were calculated thermodynamically and measured by a DTA analysis in order to describe the solidification and transformation temperature range. The MnS formation temperature was calculated thermodynamically and compared to the results of SEM/EDX investigations on fracture surfaces of hot tensile specimens torn at different temperatures after in situ melting and controlled solidification. A special focus of these investigations was the location of MnS precipitates in relation to the primary and secondary grain boundaries. To explain the results, calculations were carried out taking into account the supersaturation of manganese and sulphur during the solidification in residual melt on the primary grain boundaries.
State‐of‐the‐Art of Friction Stir Processing
Authors: Savolainen Kati , Mononen Jukka , Hänninen Hannu
Published: December 2016

The aim of this study is to present an overall view of friction stir processing (FSP), including the method, the state‐of‐the‐art regarding current studies, and possible applications. FSP is a solid‐state thermo‐mechanical processing method. It can be used to produce defect‐free, recrystallized, homogeneous, fine grained microstructures. Structures can be processed at specific locations, through‐section or to a desired depth, or entirely. The benefits obtained with FSP include elimination of casting defects and refinement of microstructures resulting in improved strength, ductility, resistance to corrosion and fatigue, and formability (including high strain rate superplasticity). Alsosurface composites can be produced by FSP.
Change of Inclusion Characteristics during Vacuum Degassing of Tool Steel
Authors: Steneholm Karin , Andersson Margareta , Jönsson Pär
Published: December 2016

The inclusion characteristics were studied during vacuum degassing by interrupting the operation at five different times after the start of operation. Slag and steel samples were collected and thereafter assessed with respect to steel and slag composition, total oxygen content, size distribution of inclusions and chemical composition of inclusions. The main conclusion is that the number of inclusions in the different size classes as well as the total oxygen content seem to reach a minimum value after around ten minutes of vacuum degassing. Furthermore, it seems to be a consistent trend that, during vacuum degassing, the top slag influences the inclusion composition.
Processing of Copper‐Containing Steel via Strip Casting ‐ a Laboratory Evaluation
Authors: Eliasson Johan , Siwecki Tadeusz , Hutchinson Bevis
Published: December 2016

Copper in recycled steel made from scrap is well known to create problems of hot shortness during rolling. The present study was carried out to ascertain how the situation could be improved when using strip casting in conjunction with direct hot rolling. This has included steels having copper contents up to 2.5 wt.% and in some cases also tin levels up to 0.1 wt.%. Laboratory simulations have been carried out to simulate the process conditions from the outlet of the strip caster through hot rolling, and the resulting materials have been examined with regard to their hot cracking behaviour and microstructural condition. Mechanical properties have also been measured on samples having different simulated coiling temperatures after hot deformation. Conditions can be established to avoid hot shortness even in steel containing high copper contents, due to the short time that is available for oxidation. Depending on the steel composition and coiling temperature, it is possible to achieve very significant strengthening due to precipitation of copper‐rich particles.
Behaviour of Surface Defects in Wire Rod Rolling
Authors: Filipović Mirjana , Eriksson Conny , Överstam Henrik
Published: December 2016

Defects are often present in rolled products, such as wire rod. The market demand for wire rod without any defects has increased. In the final wire rod products, defects originating from steel making, casting, pre‐rolling of billets and during wire rod rolling can appear. In this work, artificial V‐shaped longitudinal surface cracks have been analysed experimentally and by means of FEM. The results indicate that the experiments and FEM calculations show the same tendency except in two cases, where instability due to fairly “round” false round bars disturbed the experiment. FE studies in combination with practical experiments are necessary in order to understand the behaviour of the material flows in the groove and to explain whether the crack will open up as a V‐shape or if it will be closed as an I‐shape.
Microstructures and Mechanical Properties of High‐Strength Fe‐Mn‐Al‐C Light‐Weight TRIPLEX Steels
Authors: Frommeyer Georg , Brüx Udo
Published: December 2016

High‐strength TRIPLEX light‐weight steels of the generic composition Fe‐xMn‐yAl‐zC contain 18 ‐ 28 % manganese, 9 ‐ 12 % aluminium, and 0.7 ‐ 1.2 % C (in mass %). The microstructure is composed of an austenitic γ‐Fe(Mn, Al, C) solid solution matrix possessing a fine dispersion of nano size κ‐carbides (Fe,Mn)3 AlC1‐x and α‐Fe(Al, Mn) ferrite of varying volume fractions. The calculated Gibbs free energy of the phase transformation γfcc → ∊hcp amounts to ΔGγ→∊ = 1757 J/mol and the stacking fault energy was determined to ΓSF = 110 mJ/m2. This indicates that the austenite is very stable and no strain induced ∊‐martensite will be formed. Mechanical twinning is almost inhibited during plastic deformation. The TRIPLEX steels exhibit low density of 6.5 to 7 g/cm3 and superior mechanical properties, such as high strength of 700 to 1100 MPa and total elongations up to 60 % and more. The specific energy absorption achieved at high strain rates of 103 s−1 is about 0.43 J/mm3. TEM investigations revealed clearly that homogeneous shear band formation accompanied by dislocation glide occurred in deformed tensile samples. The dominant deformation mechanism of these steels is shear band induced plasticity ‐SIP effect‐ sustained by the uniform arrangement of nano size κ‐carbides coherent to the austenitic matrix. The high flow stresses and tensile strengths are caused by effective solid solution hardening and superimposed dispersion strengthening.
Low‐alloyed TRIP‐Steels with Optimized Strength, Forming and Welding Properties
Authors: Traint Sandra , Pichler Andreas , Sierlinger Robert , Pauli Heinrich , Werner Ewald A.
Published: December 2016

To obtain the superior strength‐ductility‐balance of TRIP‐grades, a special chemical composition in combination with well adapted processing parameters are a prerequisite. Despite of their excellent formability performance in terms of drawability as characterized by high n‐ and elongation values, compared to mild steels TRIP‐grades are challenging in the press and the body shops. The high strength level in combination with the high work hardening of TRIP‐grades result in higher levels of spring back compared to mild steels and higher press forces are required. Furthermore, a higher sensitivity to failure for sharp bending radii and a deterioration of the formability of punched edges is reported for TRIP‐grades. While spring back can only be minimized by advanced forming processes supported by new simulation techniques with improved ability to predict spring back, the sensitivity to failure under special forming conditions can be influenced by optimizing microstructural features. Contrary to the forming behaviour, which is influenced significantly by the microstructure, the weldability is mainly governed by the chemical composition and the surface condition of the material. The high carbon content of TRIP‐grades compared to mild steels results in a higher hardening potential after welding. Additionally, a fracture behaviour untypical for mild steels after destructive testing of spot welds is sometimes observed for TRIP‐grades, which is assessed critically by some OEMs.

In this work, after a discussion of the processing conditions, possibilities are demonstrated to improve the forming behaviour by an optimization of the microstructure and the spot weldability by adapting the chemical composition of low‐alloyed TRIP grades. First very promising results for TRIP‐grades with a minimum tensile strength level of 700 MPa are discussed.
Formability of High Strength Dual‐phase Steels
Authors: Tsipouridis Prodromos , Werner Ewald , Krempaszky Christian , Tragl Ernst
Published: December 2016

The application of ferritic‐martensitic dual‐phase (DP) steels has become an increasing trend in the automotive industry due to the possibility to achieve significant weight reduction and fuel efficiency with improved crash performance while keeping the manufacturing costs at affordable levels. In order to meet the different design requirements of individual auto‐body components, a wide variety of DP grades exhibiting different strength and ductility levels is currently industrially produced. Despite the numerous studies on the relationship between the mechanical properties and the microstructural characteristics of DP steels over the last decades, it is still a challenge to increase their formability at a constant strength level (or equivalently increasing the strength while maintaining a high ductility). One of the possibilities to increase strength is grain refinement. Ultrafine‐grained ferritic‐martensitic microstructures were produced by intercritical annealing of a cold‐rolled, pre‐processed dual‐phase steel. Ferrite mean grain sizes in the order of ~ 1.5 μm were obtained. The mechanical properties of these steels are studied, revealing the beneficial effect of grain refinement. Ultimate tensile strength above 800 MPa is achievable, while reaching remarkable high uniform and total elongations, which are only slightly affected by the martensite volume fraction. Moreover, the yield to tensile strength ratio can be adjusted between 0.4 and 0.5. Light and electron microscopy investigations, fracture profile and fracture surface analyses, hole expansion tests and additional ultramicrohardness measurements are used for the interpretation of the results and for the correlation of the mechanical properties and the formability characteristics with the microstructure of the steel.
Behaviour Model of Austenitic Stainless Steels for Automotive Structural Parts
Authors: Santacreu Pierre‐Olivier , Glez Jean‐Christophe , Chinouilh Guillaume , Fröhlich Thomas
Published: December 2016

One of the most important preoccupation of car manufacturers is to reduce emissions and hence to reduce weight of cars. One of the outstanding materials able to reduce weight while at the same time keeping the same crash absorption and hence safety, is austenitic steel. Austenitic stainless steels are used in crash relevant parts of cars. Moreover, designers can use their very good corrosion resistance and their well known surface aspect for structural visible parts like wheels, cross members, roof panels or tailgates. In this paper, stainless steels for automotive use are presented in detail. First, their chemical composition and tensile properties are explained. Then, a model for forming and crash behaviour is described. Using this model, stainless steels can be engineered into automotive parts and thus stainless steel can be considered as a workable and predictable material for the automotive industry.