SwePub
Sök i SwePub databas

  Extended search

Träfflista för sökning "L773:0177 4832 OR L773:1611 3683 srt2:(2010-2014)"

Search: L773:0177 4832 OR L773:1611 3683 > (2010-2014)

  • Result 1-50 of 79
Sort/group result
   
EnumerationReferenceCoverFind
1.
  • Wu, Liushun, et al. (author)
  • The effect of solid particles on liquid viscosity
  • 2011
  • In: Steel research. - : Wiley. - 0177-4832 .- 1611-3683. ; 82:4, s. 388-397
  • Journal article (peer-reviewed)abstract
    • The viscosities of solid-liquid mixtures were experimentally determined for silicon oil-paraffin system at room temperature and solid-liquid oxide mixture at steelmaking temperature. The use of oil-paraffin systems was to confirm the results of high temperature measurements, the experimental conditions being very difficult to control. The silicon oil- paraffin mixtures behaved Newtonian until the particle fraction reached 0.15. At this fraction, the mixture started deviate from Newtonian flow; though some average values could still be collected with very high uncertainty. Liquid-2CaO.SiO2 mixtures and liquid-MgO mixtures were studied at steelmaking temperature with carefully prepared particle fractions and well controlled conditions. Liquid-2CaO.SiO2 mixture behaved Newtonian even when the particle fraction reached 0.1. The results of both room temperature measurements and steelmaking temperature measurements were used to examine the applicability of the existing models. Einstein-Roscoe equation was found to be the only model applicably for the systems studied. No modification of the model parameter was found necessary, though the particles were not spherical.
  •  
2.
  • Adolfsson, Daniel, et al. (author)
  • Cementitious phases in ladle slag
  • 2011
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 82:4, s. 398-403
  • Journal article (peer-reviewed)abstract
    • Ladle slag is an internal by-product generated within the steelmaking industry during the refining of steel. The realisation of beneficial inherent properties of ladle slag as a binder supplement or substitute material is believed to be advantageous with respect to both economy and environment for steelmakers. For this reason, the current study has focused on highlighting the properties of ladle slag that are pertinent to the formation of calcium aluminate hydrates. Three fractions of ladle slag, two of which were based on different slag formers, have been characterised using XRF, XRD and calorimetric analysis. Commonly known hydraulic minerals such as mayenite, tricalcium aluminate and dicalcium silicate were detected during analysis. An important aspect in the utilisation of ladle slag is the slag handling methodology. Therefore, this study also highlights and discusses the need to reconsider slag handling procedures concerning unnecessary exposure to weathering and the possible need for further processing of the slag in order to better employ the inherent hydraulic properties of this material.
  •  
3.
  • Ahmed, Hesham, et al. (author)
  • Composite Pellets – A Potential Raw Material for Iron-Making
  • 2014
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 85:3, s. 293-306
  • Research review (peer-reviewed)abstract
    • Coke constitutes the major portion of iron-making cost and its production causes severe environmental concerns. In addition, lower energy consumption, lower CO2 emission and waste recycling are driving the Iron and steel making industry to develop “coke free, zero waste or green processes”. In the present article, an overview of possible ways to recognize a reasonable improvement in iron and steel making industry is summarized. The present discussion is focusing on the following approaches: 1. Replacing expensive coke with relatively less expensive alternate fuels having carbon as well as significant amount of hydrogen such as coal, waste plastic and biomass materials.2. Producing agglomerates from cheaper raw materials (secondary resources) as well as improving their performance in BF.3.Making the process towards higher carbon utilization by shifting the wustite equilibrium towards lower CO/CO2 ratio by using high reactive coke or catalytic activated one.4.Recycling the unused CO in the top gas by removing CO2 from the gas stream.Much attention has been paid to carbon composite agglomerates (CCA) as a promising raw material for future iron making. Production, mechanical and chemical suitability, reduction behavior, etc. are being elaborated. In addition, other possible ways to utilize CCA in alternate iron-making process has been explored.
  •  
4.
  • Albertsson, Galina, et al. (author)
  • Effect of Low Oxygen Partial Pressure on the Chromium Partition in CaO-MgO-SiO2-Cr2O3-Al2O3 Synthetic Slag at Elevated Temperatures
  • 2013
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 84:7, s. 670-679
  • Journal article (peer-reviewed)abstract
    • The objective of the present work is to get an understanding of the impact of Al2O3 addition on the phase relationships in the CaO-MgO-Al2O3-SiO2-Cr2O3 slags at low oxygen partial pressures (P-O2 = 10(-4) Pa), with a view to control the precipitation of Cr-spinel in the slag. The equilibrium phases in CaO-MgO-Al2O3-SiO2-Cr2O3 slag system in the range on 1673-1873 K have been investigated. The compositions close to the industrial slag systems were chosen. The Cr2O3 content was fixed at 6 wt% and MgO at 8 wt%. Al2O3 contents in the slag were varied in the range of 3-12 wt%. The basicity (CaO/SiO2) of slag was set to 1.6. Gas/slag equilibrium technique was adopted. The samples were heated to 1873 K and soaked at this temperature for 24 h. The samples were then slow cooled to 1673 K and equilibrated for an additional 24 h. The oxygen partial pressure was kept at 10(-4) Pa. A gas mixture of CO/CO2 was used to control the oxygen partial pressure. After the equilibration, the samples were quenched in water. The chromium distribution and phase compositions in the quenched slags were studied using SEM-WDS and XRD techniques. The results were compared with the phase equilibrium calculations obtained from FACTSAGE software and the samples equilibrated in air. The size of spinel crystals increased drastically after slow cooling followed by annealing compared to samples being quenched after soaking at 1873 K. It was also found that low oxygen partial pressure had a strong impact on chromium partition. The amount of spinel phase increases with increased Al2O3 content.
  •  
5.
  • Allertz, Carl, et al. (author)
  • A Study of Nitrogen Pickup from the Slag during Waiting Time of Ladle Treatment
  • 2014
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 85:4, s. 689-696
  • Journal article (peer-reviewed)abstract
    • An investigation of the nitrogen pickup of liquid steel from ladle slag after vacuum degassing was made. Nitride capacities, C-N, of a number of ladle slags were determined at controlled nitrogen and oxygen potentials at 1873K. The nitride capacities in the composition range studied were found to be very low. In accordance with the literature, the nitride capacity was found to increase with increasing SiO2 content. Industrial trials were performed. The nitrogen content of the steel was determined before and after vacuum degassing as well as after the waiting period. Three different trends of the variation of nitrogen content in the steel were observed. Both the laboratory study and the industrial trials revealed that the transfer of nitrogen from slag to steel was not the reason for nitrogen pickup in the steel subsequent to vacuum degassing.
  •  
6.
  • Andersson, Nils, et al. (author)
  • Investigating the effectof slag on decarburization in an AOD converter using a fundamental model
  • 2013
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 84:2, s. 169-177
  • Journal article (peer-reviewed)abstract
    • A high-temperature thermodynamics model has been coupled with a fundamental mathematical model describing the fluid flow, where boundary conditions were chosen based on data for an industrial AOD converter. Using this model, the effect of both slag phases (a liquid part and a solid part) on the decarburization was studied. More specifically, the separation of chromium oxide to liquid slag as well as the effect of the amount of rigid top slag (solid)on the decarburization was investigated. The liquid slag was considered with respect to the uptake of chromium oxide, while the rigid top slag was only considered with respect to the increase of the metallostatic pressure in the steel melt. The results suggest that separation of chromium oxide to liquid slag results in a decreased decarburization rate. The same conclusion can be drawn with respect to the amount of solid top slag.
  •  
7.
  • Andersson, Nils Å. I., et al. (author)
  • An in-Depth Model-Based Analysis of Decarburization in the AOD Process
  • 2012
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 83:11, s. 1039-1052
  • Journal article (peer-reviewed)abstract
    • A previously reported flow and reaction model for an argon-oxygen decarburization converter was extended to also include a thermodynamic description. An in-depth study of the model results has been conducted to answer how concentrations of elements and species in the converter at different locations change with time. This may contribute to the understanding of the mechanisms of the refining procedure in the argon-oxygen decarburization process. The refining procedure includes several step-wise changes of an injected gas composition to higher and higher inert gas ratio, called step changes. A step change leads to a decreased partial pressure of carbon monoxide and maintains the decarburization at a higher efficiency. The results shows early and late concentration profiles for the first injection step and suggests a way to determine when a step change should be made. Moreover, the step change could be determined by calculating the carbon concentration profiles and deciding when the carbon concentration gradients start to diminish.
  •  
8.
  •  
9.
  • Bi, Yanyan, et al. (author)
  • Three-dimensional investigations of inclusions in ferroalloys
  • 2014
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 85:4, s. 659-669
  • Journal article (peer-reviewed)abstract
    • As the requirements on material properties increase, there has been a demand on an additional knowledge on the effect of impurities in the ferroalloys on the properties. Thus, the number, morphology, size, and composition of inclusions in four different ferroalloys (FeTi, FeNb, FeSi, and SiMn) were investigated. This was done in three dimensions (3D) by using scanning electron microscopy in combination with energy dispersive spectroscopy after electrolytic extraction of the ferroalloy samples. The non-metallic and metallic inclusions were successfully analyzed on the surface of film filter. Thereafter, the particle size distribution was plotted for most of the non-metallic inclusions. The non-metallic inclusions were found to be REM oxides in FeTi, FeSi, and SiMn, Al2O3, Ti-Nb-S-O oxides in FeNb and silicon oxides in SiMn. Moreover, the intermetallic inclusions were found to be a Ti-Fe phase in FeTi, Ca-Si, and Fe-Si-Ti phases in FeSi and a Mn-Si phase in SiMn. In addition, the almost pure single metallic phases were found to be Ti in FeTi, Nb in FeNb, and Si in FeSi. As the requirements on material properties increase, the effect of impurities in ferroalloys on the steelmaking process is increasingly becoming more important. The characteristic of inclusions (morphology, number, size, and composition) in ferroalloys investigated in three-dimensional after electrolytic extraction is a good method for studying the evolution of inclusions during steelmaking.
  •  
10.
  • Brämming, Mats, et al. (author)
  • Comparison between vessel vibration and audiometry for slopping control in the top-blown BOS process
  • 2011
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 82:6, s. 683-692
  • Journal article (peer-reviewed)abstract
    • Excess slag foam growth is a frequent problem in the BOS process. In the worst case, foam is forced out of the vessel and this phenomenon, commonly called slopping, not only results in loss of valuable metal yield but also in equipment damage and lost production time. In order to minimize slopping, accurate estimation of the foam level inside the vessel is an important part of BOS process control. In the top blown BOS vessel, slopping control is achieved using both static and dynamic measures. The most common implemented technique for dynamic foam height estimation and slopping control is the audiometer system. An alternative method, vessel vibration monitoring, has been investigated as part of the work in a RFCS funded research project called IMPHOS. In order to judge the usefulness of this method, parallel vibration and audio measurements have been carried out on 130 tonne as well as on 300 tonne BOS vessels. The results show that during stable process conditions there is good agreement between the two methods with regard to foam height estimation and, as vessel vibration and audiometry are largely independent of each other, a combination of the two is likely to increase significantly the accuracy of slopping prediction. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
  •  
11.
  • Cao, Weimin, 1981-, et al. (author)
  • Calculation of Oxygen and Sulfur Average Velocity on the Iron Surface : A Two-dimensional Gas Model Study
  • 2010
  • In: Steel Research International. - : Wiley. - 1611-3683. ; 81:11, s. 949-952
  • Journal article (peer-reviewed)abstract
    • In the present work, a two-dimensional (2D) gas model is derived and used to simulate the average velocity of individual atoms of the surface active elements oxygen and sulfur on the Fe(100) surface. The average velocity of oxygen and sulfur atoms was found to be related to the vibration frequencies and minimal energy barrier. The calculated results are based on data from density functional calculations combined with thermodynamics and statistical physics. The calculated average velocity of oxygen on the Fe (100) is lower than that of sulphur. This is because of the stronger interaction between oxygen and the first iron layer. We conclude that our simple 2D gas model may be useful for simulating and understanding the complex interfacial phenomena in the steelmaking refining process from an atomic point of view.
  •  
12.
  • Chen, Chao, et al. (author)
  • Effects of Salt Tracer Amount, Concentration and Kind on the Fluid Flow Behavior in a Hydrodynamic Model of Continuous Casting Tundish
  • 2012
  • In: Steel Research International. - : John Wiley & Sons. - 1611-3683 .- 1869-344X. ; 83:12, s. 1141-1151
  • Journal article (peer-reviewed)abstract
    • The hydrodynamic modeling method that widely used to simulate the fluid flow was reconsidered and discussed in this paper. The effects of injected salt tracer amount, concentration and kind on the fluid flow behavior in a hydrodynamic model tundish were investigated. The results were compared with the mathematical modeling calculation results, that the tracer density effect was eliminated. The residence time distribution (RTD) curve of tracer introduced deviated to the left side of the calculated curve, besides the deviation was increased as dimensionless tracer amount (the ratio of tracer amount to hydrodynamic model tundish volume) increased from 0.202 × 10−3 to 1.008 × 10−3. The results of tracer concentration study were similar, namely the deviation was increased with concentration increased; on the other hand, the deformation of a “stair-shape” RTD curve occurred when tracer concentration was much lower (at dimensionless tracer amount of 0.168 × 10−3 with converting to saturated solution). Besides, the effect of tracer kind on the accuracy of hydrodynamic modeling was also studied; the measurements of KCl solution with lower density than that of NaCl solution exhibited more of accuracy. Finally, the optimized tracer in hydrodynamic model tundish of present work is saturated KCl solution with dimensionless tracer amount of 0.202 × 10−3.
  •  
13.
  • Chychko, Andrei, et al. (author)
  • Fe2MoO4 as a precursor material for Mo alloying in steel : (Part II): Upscaling test
  • 2011
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 82:8, s. 886-897
  • Journal article (peer-reviewed)abstract
    • The Mo yield when using three different alloying mixtures (MoO3 +C; MoO3 +C + FeOx; and MoO3+ C + CaO) was tested both in laboratory experiments (16 g and 0.5 kg scale) and industrial trials (3 ton scale). The alloying is based on in-situ formation of compounds of Mo in the mixtures from molybdenite concentrate with industrial grade Fe 2O3. Thermogravimetry (TGA) and X-ray diffraction (XRD) analyses were performed to identify the reduction steps and final products of the alloying mixtures. At least two steps of mass change were discovered during the reduction of all tested mixtures by carbon. The Mo yield for MoO3 + C mixture is 93% which was confirmed by both laboratory and industrial experiments. The Mo yield for MoO3 + C + CaO mixture is around 92% during 16 g scale laboratory and 3 ton scale industrial tests. The best results were obtained in the case of the mixture which contained FeOx, MoO3 and C, resulting in the Mo yield up to 98% at all the experiment scale levels. It was found that the combination of both lower evaporation and fast reduction by carbon of the mixture along with further dissolution in steel are necessary to provide high Mo yield during steel alloying. The calculated mass balance of 3 ton trial heats showed that only a small part of initial Mo amount (8-13 ppm) has gone into slag. Copyright
  •  
14.
  • Chychko, Andrei, et al. (author)
  • MoO3 Evaporation Studies from Binary Systems towards Choice of Mo Precursors in EAF
  • 2010
  • In: Steel Research International. - : Wiley. - 1611-3683. ; 81:9, s. 784-791
  • Journal article (peer-reviewed)abstract
    • The evaporation rate of molybdenum oxide from mixtures with CaO or MgO was studied in the temperature range 300-1573 K. The investigations were carried out using high temperature X-ray diffraction and thermogravimetry. Further, additions of these precursors to molten steel in the laboratory scale and the Mo yield achieved were determined. The X-ray studies show that the calcium molybdate is formed from the oxide mixture in the temperature interval 773-873K, which precedes the beginning of evaporation of MoO3. Results of thermogravimetric studies with mixtures CaO and MgO with MoO3 as well as the compounds CaMoO4 and MgMoO4 confirm the above results. Addition of various molybdenum precursors, viz, the mixtures of carbon with pure MoO3, CaMoO4 and MgMoO4, as well as oxide mixtures (CaO + MoO3, MgO + MoO3) show that the highest yield was observed for CaMoO4 + C and MoO3 + C mixtures, while MgO + C + MoO3 mixture showed much lower yield.
  •  
15.
  • Chychko, Andrei, et al. (author)
  • Synthesis and characterization of Fe2MoO4 as a precursor material for Mo alloying in steel
  • 2011
  • In: Steel Research International. - : Wiley. - 1611-3683. ; 82:3, s. 269-276
  • Journal article (peer-reviewed)abstract
    • Iron molybdate (Fe2MoO4) has been studied as a new potential precursor for Mo additions in high alloy steel processing. Fe2MoO4 was synthesized by high temperature reactions between MoO3, FeOx and carbon by holding the mixture first for 23 hours at 873K and then for 16 hours at 1373 K. The Fe2MoO4 syntheses were carried out with pure reagents as well as commercial grade materials supplied by steel industry. A thermodynamic analysis of the stabilities of the various phases in the Fe-Mo-O-C quaternary was carried out. The synthesis processes, leading to the Fe2MoO4 formation from the precursors and further reduction by carbon were studied with the aid of thermogravimetric analysis (TGA), high-temperature X-ray diffraction (HT-XRD) and evolved gas analysis by gas chromatography (GC). The maximum temperature in the case of all the experiments was 1373 K. It was found that the reactions between the precursor components start already above 873 K. The precursor mixture from commercial grade materials offers an economically advantageous process route with high Mo yield in steel.
  •  
16.
  • Davydenko, Arkadiy, et al. (author)
  • Characterization of Briquettes Used for Slag Foaming in the EAF during Stainless Steel Production
  • 2014
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 86:2, s. 137-145
  • Journal article (peer-reviewed)abstract
    • The modern sustainable stainless steel making industry is characterized by different factors such as an efficient utilization of energy in the Electric Arc Furnace (EAF) by a slag foaming practice and an utilization of waste products from its own production facilities. In this study, the foaming briquettes applied for a combined slag foaming and waste product reduction in the EAF are characterized. The recipes of the briquettes were made based on a literature review and previous experience. Afterwards, the composition and density of briquettes were estimated and compared to calculated data. Moreover, weight reduction experiments were made on a laboratory scale at temperatures up to 1500-°C in an argon atmosphere in order to characterize the products (metal, slag, and gas). Based on these results, the calculations were compared with experimental data. The following main results were found: (i) the density of briquettes can be successfully verified, (ii) briquettes have different mechanical properties depending on the materials used for production of briquettes, and (iii) the briquettes yield in different amounts of metal and gas. Moreover, it was found that light briquettes (without FeCr) produced almost double the amount of gas in comparison with heavy briquettes (containing FeCr); valuable metals can be recovered from briquettes, and recipes of briquettes can be optimized based on the amount of metal droplets in briquettes and the total utilization of carbon. This study is focused on a characterization of briquettes, which are used for slag foaming and waste product reduction in the Electric Arc Furnace (EAF) during the stainless steel production. The experimental data is compared with calculations according to the obtained results.
  •  
17.
  • Deng, Tengfei, et al. (author)
  • Dissolution of Lime in Synthetic 'FeO'-SiO2 and CaO-'FeO'-SiO2 Slags
  • 2010
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 81:5, s. 347-355
  • Journal article (peer-reviewed)abstract
    • Dissolution of different CaO samples into molten synthetic 'FeO'-SiO2 and 'FeO'-SiO2-CaO slags was carried out in a closed tube furnace at 1873K. The slag was kept stagnant. It was found that the dissolution rate was very fast when CaO rod was dipped into 'FeO'-SiO2 slag. In the case of 'FeO'-SiO2-CaO slag, the dissolution of CaO rod in the stagnant slag was retarded after the initial period (2 minutes). Only less than 16 percent CaO reacted with the slag, irrespective of the type of lime. Three phase-regions were identified in the reacted part of the lime rod by SEM-EDS analysis. The formation of these regions was explained thermodynamically. A dense layer of 2CaO center dot SiO2 was found to be responsible for the total stop of the dissolution. It could be concluded that constant removal of the 2CaO center dot SiO2 layer would be of essence to obtain a high dissolution rate of lime. In this connection, it was found necessary to study the dissolution of lime in moving slag to reach a reliable conclusion regarding the relevance of the reactivity obtained by water ATSM test to the real reactivity of lime in high temperature slag.
  •  
18.
  • Deng, Tengfei, et al. (author)
  • Experimental Design for the Mechanism Study of Lime Dissolution in Liquid Slag
  • 2012
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 83:3, s. 259-268
  • Journal article (peer-reviewed)abstract
    • The applicability of rotating rod technique in the study of lime dissolution in slag was investigated. Both computational fluid dynamic (CFD) and cold model experiments showed that the mass transfer due to radial velocity introduced by forced convection was zero if the rod was long. The mass transfer by forced convection was also less important in comparison with natural convection and diffusion when the rod was half length of the height of the bath. This finding was in accordance with the criteria put forward by the original work that the method could only be applicable when a thin disk (instead of rod) with big diameter and big liquid bath were used. To study the lime dissolution by forced convection a new experimental technique was developed. A cube was placed in the slag that was eccentrically stirred. The whole system, viz. the sample along with the slag could be quenched. The new technique could study the effect of forced convection on the dissolution. The microscopic study on the quenched slag-lime samples could reveal the dissolution mechanism successfully.
  •  
19.
  • Doostmohammadi, Hamid, et al. (author)
  • A Comparison of a Two-Dimensional and a Three-Dimensional Method for Inclusion Determinations in Tool Steel
  • 2010
  • In: STEEL RES INT. - : Wiley. - 1611-3683. ; 81:5, s. 398-406
  • Journal article (peer-reviewed)abstract
    • To produce clean commercial tool steel the non-metallic inclusions characteristics have to be known, since they influence the mechanical properties of steel. In this work, inclusion characteristics in steel samples from plant trials were studied. The samples were collected in the steel plant according the two following methods: (a) 2D investigations of inclusions by a cross sectional method and (b) 3D investigations of inclusions collected on a film filter after electrolytic extraction. More specifically, the chemical composition, morphology, number and size distribution of inclusions in tool steel samples taken from ladle during melt treatment were determined by both methods. In both methods SEM equipped with EDS was used for compositional analysis of inclusions. In addition, in the cross sectional method an automated detection program called 'INCAFeature' was used to collect more statistics of non-metallic inclusions. The composition of inclusions larger than 5 mu m was found to contain 49% CaO based on the results from both methods. However, for smaller inclusions it was found that the accuracy of the 2D method was less than that of the 3D method due to the influence of the metal matrix on the results. In addition, it was found that a critical inclusion size of 4 mu m could be defined for the 3D method, above which the standard deviation in composition determination was very low.
  •  
20.
  • Doostmohammadi, Hamid, et al. (author)
  • Inclusion Characteristics of Bearing Steel in a Runner after Ingot Casting
  • 2010
  • In: STEEL RES INT. - : Wiley. - 1611-3683 .- 1869-344X. ; 81:2, s. 142-149
  • Journal article (peer-reviewed)abstract
    • In the uphill teaming method of ingot casting molten metal from the ladle goes into the runner system, which feeds one or several ingot moulds. This method is still important for production of bearing steel. In order to make clean steel, which has a controlled amount of inclusions, good understanding of inclusions characteristics is necessary In this work non-metallic inclusions of steel left in the runner part of an ingot casting system were studied. Inclusion type, size, and morphology were the main focus of this study A scanning electron microscope (SEM) was used to assess inclusion size and morphology The chemical composition of inclusions was determined by SEM equipped with EDS. An automated program called 'INCAFeature' was used to collect statistics of inclusion characteristics. Based on the statistical analysis of inclusion composition, four types of inclusions including oxides, sulfides, carbonitrides and complex inclusions were defined. The inclusion characteristics in the runner were also compared to literature data of inclusions found in ladle and mould samples.
  •  
21.
  • Doostmohammadi, Hamid, et al. (author)
  • Use of Computational Thermodynamic Calculations in Studying the Slag/Steel Equilibrium during Vacuum Degassing
  • 2010
  • In: STEEL RES INT. - : Wiley. - 1611-3683. ; 81:1, s. 31-39
  • Journal article (peer-reviewed)abstract
    • The effectiveness of a ladle refining process for production of tool steel with focus on the top slag is studied using computational thermodynamic calculations. The theoretical assessment was based on compositional data of steel and slag samples collected during trials in a plant equipped with a 65-t EAF, a ladle furnace and a vacuum degasser The calculation of slag-metal equilibrium during ladle treatment was performed for top slag excluding (Case A) and including (Case B) slag carryover and deoxidation products. The predictions showed that slag carryover and deoxidation products in the ladle significantly affect the composition of the top slag. Thus, these conditions must be taken into consideration when predicting the actual top slag composition. It was also found that it is possible to predict the final aluminium and sulphur content in steel based on the same calculation approach.
  •  
22.
  • Däcker, Carl-Åke, et al. (author)
  • The influence of mould powder properties on shell formation in continuous casting of steels
  • 2010
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 81:10, s. 899-907
  • Journal article (peer-reviewed)abstract
    • For peritectic steel grades the shell formation is uneven resulting in quality problems such as surface cracks. Production of these steels calls for good control and knowledge of the critical factors for shell formation. By optimisation of process parameters, it is possible to enable production of crack sensitive slabs for heavy plate. This also gives a unique possibility to study the interaction between process parameters and shell formation. The paper presents the results from two large investigations with this ambition covering the total of 27+30 heats of 220 tons of steel at SSAB EMEA-Oxelösund and concludes how surface cracks can be significantly decreased. © 2010 Wiley-VCH Verlag GmbH & Co.
  •  
23.
  • Ek, Mattias, et al. (author)
  • Effect of Inert Gas Flow Rate on Homogenization and Inclusion Removal in a Gas Stirred Ladle
  • 2010
  • In: STEEL RES INT. - : Wiley. - 1611-3683. ; 81:12, s. 1056-1063
  • Journal article (peer-reviewed)abstract
    • In the present study, the effect of gas flow rate on homogenization and inclusion removal in a gas stirred ladle was investigated. Both industrial trials and cold model experiments were conducted. CFD calculation was also carried out as an auxiliary tool. The mixing times predicted by CFD simulation agreed well with both the model experiments and industrial data. 99% mixing could be achieved in about 2-3 minutes. The increase of flow rate of inert gas would not improve the mixing substantially, while the mixing time decreased somewhat with the increase of gas flow rate. The water model study showed also that the gas flow rate had a negligible effect on the rate of inclusion removal. Both the experiments and CFD calculation strongly suggested that a low gas flow rate should be applied in the ladle treatment.
  •  
24.
  • Ek, Mattias, et al. (author)
  • Study of Penetration Depth and Droplet Behavior in the Case of a Gas Jet Impinging on the Surface of Molten Metal using Liquid Ga-In-Sn
  • 2012
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 83:7, s. 678-685
  • Journal article (peer-reviewed)abstract
    • To study the penetration depth in the case of a gas jet impinging on the surface of liquid steel, cold model experiments were carried out using a liquid alloy GaInSn, which had similar physical properties as liquid steel. A HCl solution was used to simulate the top slag. The top phase was found to have appreciable effect on the penetration depth. Comparison of the experimental data with the predictions of the existing models indicated that most the model predictions deviated from the experimental results at higher lance heights and gas flow rates. New model parameter was suggested based on the present experimental data. The observation of the formation and movement of metal droplets generated by the gas jet was also made. The velocity of the droplet was found to be at a level only about 1% of the terminal velocity. This low velocity suggested that the turbulent viscosity played important role and the droplets could have long resident time in the slag.
  •  
25.
  • El-Bealy, Mostafa Omar (author)
  • Advanced solute conservation equations for dendritic solidification processes : Part I: Experiments and theory
  • 2013
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 84:6, s. 565-583
  • Journal article (peer-reviewed)abstract
    • The macrosegregation formed in dendritic equiaxed structure during early stages of solidification of Al-4.5%Cu alloy has been studied by experimental work and by metallurgical study of cast samples taken from the experimental work. An experimental work was conducted to study the coupled effect of natural convection streams, interdendritic strain and mushy permeability of Al-4.5%Cu aluminum alloy solidified in horizontal rectangular parallelepiped cavity at different superheats. The metallurgical study includes macro-microstructure evaluation, measurements of grain size of equiaxed crystals and macrosegregation analysis. This study shows that the level of surface segregation exhibiting as positive segregation varies with superheat whereas the rest of inner ingot areas show the light fluctuation in segregation values. In addition to experimental work, there is a mathematical study which contains a complete derivation of local solute redistribution equations based on Fleming's approach under different solute diffusion mechanisms in the dendritic solid. This derivation includes also the effects of interdendritic strain and mushy permeability on the local solute redistribution distribution. Owing to the length of the study, it is presented in two parts. The first part describes the experimental work and its results as well as a detail derivation of solute conservation equations. This part also involves comparison and discussion between existing and proposed solute conservation equations. The second part contains the mathematical analyses of a two dimensional mathematical model of fluid flow, heat flow, solidification, interdendritic strain and macrosegregation. Also, this part also contains the numerical simulations by using finite difference technique "FDT" to create convection patterns, heat transfer, interdendritic strain, and macrosegregation distributions. This part also includes comparisons between the available measurements and model predications as well as full discussion of different model simulations. The mechanism of interdendritic strain generation and macrosegregation formation during solidification of dendritic equiaxed structure under different diffusion mechanisms in dendritic solid has also been explained and discussed. Macrosegregation in dendritic equiaxed structure during the early stages of solidification of Al-4.5%Cu alloy has been studied experimentally. The metallurgical study includes macro-microstructure evaluation, measurements of grain size of equiaxed crystals, and macrosegregation analysis. In addition to the experimental work, there is a mathematical study which contains a complete derivation of local solute redistribution equations based on Fleming's approach under different solute diffusion mechanisms in the dendritic solid.
  •  
26.
  • El-Bealy, Mostafa Omar (author)
  • Advanced solute conservation equations for dendritic solidification processes part II : Numerical simulations and comparisons
  • 2013
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 84:6, s. 584-606
  • Journal article (peer-reviewed)abstract
    • The mathematical model of derived solute equations in part I for equiaxed dendritic solidification with melt convection streams and interdendritic thermo-metallurgical strain is applied numerically to predict macrosegregation distributions with different diffusing mechanisms in dendritic solid. Numerical and experimental results are present for solidification of a Al-4.5% Cu alloy inside horizontal rectangular cavity at different superheats. The numerical simulations were performed by using simpler method developed by Patanker. The experiments were conducted to measure the cooling curves via thermocouples and the metallurgical examinations to measure the grain size and macrosegregation distributions in Part I. Preliminary validity of the model is demonstrated by the qualitative and quantitative agreements between the measurements and predications of cooling curves and predicted macrosegregation distributions including mushy permeability and interdendritic strain. In addition, several important features of macrosegregation in equiaxed dendritic solidification are identified through this combined experimental and numerical study. Also, quantitative agreements between the numerical simulations and experiments reveal several areas for future research work. The differences and errors between predicted macrosegregation results under different diffusing mechanisms have been discussed. The mathematical model of derived solute equations in Part I for equiaxed dendritic solidification with melt convection streams and thermal is applied numerically to predict macrosegregation distributions with different diffusing mechanisms in dendritic solid. Numerical and experimental results are present for solidification of a Al-4.5% Cu alloy inside horizontal rectangular cavity at different superheats.
  •  
27.
  • El-Bealy, Mostafa O. (author)
  • Air-Water Mist and Homogeneity Degree of Spray Cooling Zones for Improving Quality in Continuous Casting of Steel
  • 2011
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 82:10, s. 1187-1206
  • Journal article (peer-reviewed)abstract
    • A theoretical investigation used previous experimental works for validation of model predications and for studying the effect of different nozzle designs on the quality of continuously cast steel slabs has been undertaken. This is by optimizing the homogeneity degree of cooling pattern "HDCP'' between a pair of rolls. The idea behind this technique is to maximize the solid shell resistance against thermo-metallurgical and mechanical stresses and therefore minimizes the defects generated in different cooling zones. A 2-D mathematical model of thermal, solidification, solid shell resistance and cooling conditions has been developed. The model determines the temperature distributions, the different phases associated with the solidification and three phase peritectic reaction L + delta -> gamma of Fe-0.12%C steel alloy as well as isotherms. The effect of different cooling patterns for various spray cooling systems on the homogeneity degree and solid shell resistance are examined. In additional to traditional water and air-water (AWM) nozzles, a new design of air-water mist nozzle has been proposed to improve the homogeneity degree of spray cooling system. The results indicate generally that the increasing in the homogeneity degree of cooling conditions is proportional to the increasing in the solid shell resistance and therefore to the improving of slab quality. Model predications of different effects of different nozzle designs on the surface and inner quality levels are compared and discussed in the mold and secondary spray cooling zones.
  •  
28.
  • Elfsberg, Jessica, et al. (author)
  • Measurements and Calculation of Interfacial Tension between Commercial Steels and Mould Flux Slags
  • 2011
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 82:4, s. 404-414
  • Journal article (peer-reviewed)abstract
    • Surface quality of continuously cast is strongly influenced by the interfacial tension between steel and mould flux slag. The meniscus shape and the inclusion entrapment are directly determined by interfacial tension. To achieve a better understanding of the continuous casting process, the interface between four commercial steels and the mould fluxes used at the continuous casting of each steel grade have been investigated. The situation at this interface is determined by the surface tension of steel and slag respectively and also by the mass transfer occurring across the interface. The surface tensions of the mould flux slags have been measured by sessile drop method. The results indicate that the surface tension of mould flux slags decreases with increasing temperature but does not vary so much within the present composition range. Interfacial tensions between steel samples and mould flux slags have been measured in the same way with the aid of X-ray unit. Estimation of interfacial tension from the steel and slag composition was done by applying empirical models. The measured and the calculated values were in agreement. The interfacial tension was lower for higher alloyed steel grades according to both experiments and calculations though the influence of surface active elements is significant.
  •  
29.
  • Engström, Fredrik, et al. (author)
  • Crystallization behaviour of some steelmaking slags
  • 2010
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 81:5, s. 362-371
  • Journal article (peer-reviewed)abstract
    • The present study was aimed at highlighting the final properties of two different steelmaking slags which undergo different cooling rates. The experiments were conducted in laboratory scale using an induction furnace. One of the slags originates from an electric arc furnace (EAF) (high-alloyed) and the second slag from a basic oxygen furnace (BOF). The treatment of the slag included re-melting along with different cooling rates. The material collected from the tests was characterized through X-ray diffraction, scanning electron microscopy as well as thermodynamic calculations which were compared with experimental results, for confirmation. The results indicate that both the EAF and BOF slags show increased reactivity with water, as well as a decrease in crystal size when rapid cooling is applied. The wüstite-type solid solution (Mg,Fe,Mn)O varies in composition depending on the cooling conditions. Metastable Ca3SiO5 was found in the rapidly- cooled BOF slag.
  •  
30.
  • Engström, Fredrik, et al. (author)
  • Leaching Behavior of Aged Steel Slags
  • 2014
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 85:4, s. 607-615
  • Journal article (peer-reviewed)abstract
    • Large amounts of slag are generated by the Swedish Steel Industry each year. The Electric Arc Furnace process generates about 200 000 ton of slag per annum, from which approximately 40% is deposited. An alternative to deposit is to use slag as road construction material. However, leaching of metals from the slag can be a reason to limit slag use in road construction. The aim of this work was to investigate how stable these materials are when aged, in an environment open to seasonable weather conditions, with respect to leaching and mineralogy. Three different EAF-slags from domestic steel plants were used in this study. The materials were characterized after 0, 6, 12, 18, and 24 months to evaluate the ageing process. The analytical techniques that were used to evaluate the effect of ageing are scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and a standard test for leaching. The changes in ageing behavior differ between the three materials. The conductivity and the pH decreases with time for all samples. The leaching of calcium, chromium as well as aluminum decreases with time while the leaching of magnesium increases. CaCO3 was formed on slag surfaces as CaO reacts with moisture and CO2 from the air.
  •  
31.
  • Ericsson, Ola, et al. (author)
  • Effect of Slag Protection System and Sample Geometry on Homogeneity of Total Oxygen Content in Samples from Liquid Steel
  • 2011
  • In: Steel Research International. - : Wiley. - 1611-3683. ; 82:3, s. 222-229
  • Journal article (peer-reviewed)abstract
    • Many kinds of disposable samplers are available for sampling of liquid steel during steelmaking. Depending on slag protection, they can be divided into two main groups: metal-cap-protected and argon-protected samplers. For high quality steels, a correct determination of inclusion characteristics in metal samples is important for an improved process control. This paper seeks to investigate the effect of slag protection system, and sample geometry, on deviation and total content of oxygen within samples from the ladle treatment of liquid duplex stainless steel. The homogeneity with respect to total oxygen content was determined for different zones in the body, pin and inlet part of Bjorneborg and Lollipop (6 and 12mm thickness) samples. The results showed low, and stable, contents of oxygen in the argon-protected samples. However, the total oxygen content, and deviation of oxygen, in metal-cap-protected samples was much higher, especially in the body part of the samples. Finally, it was found that the oxygen content heterogeneity in the metal-cap-protected samples increased with a decreased sample weight. Based on the obtained results, the 6mm thick Lollipop sample with argon-protection is recommended for determination of total oxygen content and oxide inclusion characteristics.
  •  
32.
  • Glaser, Björn, et al. (author)
  • Determination of Experimental Conditions for Applying Hot Wire Method to Thermal Conductivity of Slag
  • 2013
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 84:7, s. 649-663
  • Journal article (peer-reviewed)abstract
    • In order to apply the hot wire method for metallurgical slags at steelmaking temperatures, a numerical model was developed, cold model experiments were conducted and test measurements using a high temperature experimental setup were carried out. To minimize natural convection and obtain more reliable measurements, the crucible diameter, the hot-wire diameter, the applied current, the position of the wire in the crucible, and the cooling on the upper surface of the crucible were studied. Investigations into the choice of sheathing material of the circuit exposed to the slag were also made. It was found that only certain materials were suitable for slag measurements depending on slag composition and temperature. The electrical resistivity of the hot wire was measured to make the thermal conductivity calculation more reliable. The wire diameter also played a major role, because of the heat generation per surface area. The thermal conductivity should be derived from the values measured during the first seconds. In this initial stage, the effect of the natural convection as a function of the wire position in the crucible, the cooling on the top surface, and the diameter of the crucible are negligible. A compromise has to be made in choosing the electrical current, since higher current results in higher sensitivity but at the same time in more natural convection.
  •  
33.
  • Glaser, Bjoern, et al. (author)
  • Fluid Flow and Heat Transfer in the Ladle during Teeming
  • 2011
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 82:7, s. 827-835
  • Journal article (peer-reviewed)abstract
    • A two dimensional axisymmetric model was developed to predict the heat flux in a steelmaking ladle during the teeming process. The model predicts dynamically the flow fields in both liquid phase and gas phase along with the movement of the liquid upper surface. The model also predicts the temperature distributions in the liquid metal, gas phase and all layers in the ladle wall. Industrial measurements using infrared radiation camera inside the ladle after teeming and at the wall outside the ladle during the whole process were carried out. The model predictions were found to be in agreement with the measured data. It was found that the heat transfer to the surrounding atmosphere and the conductivity of the highly insulating layer were the most important factors for the heat loss. The decrease of the thickness of the working lining was found to have limited effect on the total heat flux.
  •  
34.
  • Glaser, Björn, et al. (author)
  • Thermal Modelling of the Ladle Preheating Process
  • 2011
  • In: Steel Research International. - : John Wiley & Sons. - 1611-3683 .- 1869-344X. ; 82:12, s. 1425-1434
  • Journal article (peer-reviewed)abstract
    • To predict the temperature distribution in the ladle wall during the preheating process a two dimensional model was developed. The model calculated the heat transfer and the velocity field in the gas phase inside the ladle as well as the heat transfer in the solid walls during the preheating process. Measurements of the temperature in an industrial lade were carried out using an infrared radiation (IR) camera. The measurements were made inside and outside the ladle. The model predictions were found to be in reasonably good agreement with the measured temperatures. It was found that the preheating time could be minimized when the working lining became thinner. The effect of the distance between the lid and the ladle was also studied by the model. The results indicated that there was no significant temperature change on the upper side wall of the ladle. On the lower side wall and bottom the temperature changed slightly. The temperature difference in the lower part of the ladle could be explained by the larger flame distance from the bottom layer.
  •  
35.
  • Granbom, Ylva, et al. (author)
  • Simulation of the Soaking and Gas Jet Cooling in a Continuous Annealing Line using Dilatometry
  • 2010
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 81:2, s. 158-167
  • Journal article (peer-reviewed)abstract
    • The present study concerns the simulation of a continuous annealing line (CAL), using dilatometry. Simulations of CAL have been performed on four commercial steel grades with different chemical compositions in order to investigate how the alloying elements C, Mn, Si and B affect the microstructure and hardness of dual phase (DP) and martensitic steels. Three annealing cycles corresponding to those used in a CAL have been applied. When annealing intercritically, as is the case in DP-steel production, the materials do not reach equilibrium during soaking. Mn and C increase the austenite content and consequently the hardness of the materials. Higher levels of Si (0.4 wt %) are required to retard the formation of new ferrite during cooling in the gas jet section, prior to quenching. 6 increases hardenability effectively when annealing in the austenite region but is not as efficient during intercritical annealing, which implies that boron restrains ferrite nucleation rather than impeding ferrite growth. Results from DICTRA calculations show that it is possible to simulate the phase transformations during soaking, gasjet cooling and quenching.
  •  
36.
  • Grinder, Olle (author)
  • Surface Oxidation of Steel Powder
  • 2010
  • In: STEEL RES INT. - : Wiley. - 1611-3683. ; 81:10, s. 908-913
  • Journal article (peer-reviewed)abstract
    • Powder metallurgical production of fully dense steel such as high-speed steel, tool steel and stainless steel is of large industrial importance. The process route is as follows: melting inert gas atomization encapsulation hot isostatic pressing and subsequently often also hot forming. Final products comprise near-net-shape components, billets and semi-finished parts e.g. rods. The mechanical and functional properties of the PM steels are often superior to those of conventional manufactured steels over casting + forging with the same chemical composition. The properties of the PM-steels are highly dependant on their oxide contents. There are three types of oxides in PM-steels: exogenous and endogenous slag inclusions and oxides originating from surface oxidation of the atomized particles. The negative effect from the inclusions on the properties of the PM-steels is dependant on their origin. The exogenous inclusions are normally highly detrimental while the endogenous inclusions are harmless. Surface oxides are harmful when present in larger amounts. A special experimental technique was developed to study surface oxidation of powders. Large emphasis was also focused on sampling to enable that the oxygen determination was representative of the bulk powder. The results thus obtained gave most important information on when and how the atomized powder was oxidized during the process. Furthermore, a new methodology was developed based on the experimental results. It is now used world-wide for quality control of atomized steel powders. This method enables the distinction between exogenous + endogenous inclusions and surface oxides.
  •  
37.
  • Jelkina Albertsson, Galina, et al. (author)
  • Effect of the Heat Treatment on the Chromium Partition in Cr-Containing Industrial and Synthetic Slags
  • 2014
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 85:10, s. 1418-1431
  • Journal article (peer-reviewed)abstract
    • In the present work, the effects of the slag composition and heat-treatment conditions on the phase relationships in a number of Cr-containing industrial and synthetic slags were investigated with a view to control the precipitation of Cr-spinel in the slag phase. Gas/slag equilibrium technique was used for the chromium partition and the phase relationship study. The phase relationships in synthetic slags and industrial EAF slags supplied by Swedish steelmaking plants have been investigated experimentally in the temperature range of 1473-1873 K. The slags were re-melted, slow-cooled to, and soaked at targeted temperatures in controlled atmosphere. Two different heat-treatment sequences were used in the present experiments. The oxygen partial pressure (p(O2) = 10(-3) Pa) was maintained by a suitable mixture of CO and CO2 gases. Phases present and their compositions in the quenched slags were studied using X-ray diffractometry (XRD) and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). The chromium content in the phases present was analyzed using wavelength-dispersive spectrometer (WDS). Chromium partition was found to depend on the heat-treatment temperature.
  •  
38.
  • Kanbe, Yuichi, et al. (author)
  • Analysis of Largest Sulfide Inclusions in Low Carbon Steel by Using Statistics of Extreme Values
  • 2011
  • In: Steel Research International. - : Wiley. - 1611-3683. ; 82:4, s. 313-322
  • Journal article (peer-reviewed)abstract
    • The statistics of extreme values was applied for the determination of the largest sulfide inclusions with different morphology in low carbon steel samples by using both two-dimensional (2D) observations on the polished cross section and three-dimensional (3D) observations on a surface of a film filter after electrolytic extraction of the samples. It was found that the globular, rod-like and dendritic sulfides in the molten steel sample as well as the elongated sulfides in the rolled steel sample can be successfully extracted from the both samples, and analyzed precisely by using extreme value analysis in 3D. Based on the geometrical considerations of the probability for measurement of the true length of rod-like and elongated inclusions on a cross section, it was found that this probability for inclusions decreases dramatically with an increasing real aspect ratio value of them. Particularly for the determination of the true length for elongated inclusions in the rolled steel sample by 2D investigations on a metal cross section, it is required to be cut investigating section of steel sample within +/- 1 degree against rolling direction. Therefore, a 3D observation is considered to be more preferable and accurate than the conventional cross sectional observation in 2D, due to the possibility for the measurements of the real size of them.
  •  
39.
  • Kazemi, Mania, et al. (author)
  • Study on Direct Reduction of Hematite Pellets Using a New TG Setup
  • 2014
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 85:4, s. 718-728
  • Journal article (peer-reviewed)abstract
    • A new thermogravimetric setup was developed to study direct reduction of iron oxide under well-controlled experimental conditions. Pure and industrial hematite samples were isothermally reduced by hydrogen and carbon monoxide gaseous mixtures. Influences of gas composition, gas flow rate, and temperature on reduction were investigated. Reduction rates obtained using the new setup were higher compared to conventional thermogravimetric method. This difference was due to the time required to replace the inert gas with the reactant gas in the conventional method, which led to lower reduction rate at the initial stage. Carbon deposited on the surface of the pellets at relatively high gas flow rates and at low temperatures. The presence of pure iron and high carbon potential in the gas phase were the cause for carbon deposition. Study of partially reduced samples illustrated that the outer layer of pellet with high iron content thickened as reduction proceeded inside the pellet. Closure of micro-pores and formation of dense iron phase in this layer decelerated diffusion of reactant and product gases, and led to decrease of reduction rate at later stages of reaction. At lower temperatures, this effect was coupled with carbon deposition. Therefore, the reduction was seriously hindered.
  •  
40.
  •  
41.
  • Lindell, David, et al. (author)
  • Pickling of Process-Oxidised Austenitic Stainless Steels in HNO3-HF Mixed Acid
  • 2010
  • In: STEEL RES INT. - : Wiley. - 1611-3683 .- 1869-344X. ; 81:7, s. 542-551
  • Journal article (peer-reviewed)abstract
    • Oxide formation during production annealing and the subsequent pickling response in mixed acid have been studied. The aims were to characterise the oxides formed and to understand how the pickling mechanism and kinetics are affected by the nature of the oxide. Totally, eight different versions of the austenitic stainless steel grades AISI 301, 304L and 309L were studied, all annealed in production lines. Cold rolled oxides (formed during annealing) are thin (< 1 mu m), dense and formed in a multilayered manner. Hot rolled oxides (formed during reheating, hot rolling and annealing) are thicker (>1 mu m) and more heterogeneous in thickness and composition. The dissolution rate of the chromium depleted layer (CDL) under the oxide is the most important factor for the overall pickling rate. The permeability of acid through the oxide and the tendency of the oxide to spall are also important factors affecting the pickling kinetics. The dense oxide formed on cold rolled materials can to some extent hinder the acid to reach the CDL. The oxides on hot rolled materials are porous and do not provide such a barrier but they are thicker and thereby more difficult to remove. Shot-blasting prior to pickling of the hot rolled materials improves the pickling performance because it thins the oxide, improves the permeability and increases the tendency of the oxide to spall during the pickling step.
  •  
42.
  • Lindström, David, et al. (author)
  • Functions of Mg and Mg-CaO mixtures in hot metal desulfurization
  • 2014
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 85:1, s. 76-88
  • Journal article (peer-reviewed)abstract
    • The mechanisms of hot metal desulfurization using Mg and Mg-CaO mixtures were studied in a newly designed set-up. It was found that most of the added Mg quickly escaped in 2 s. MgS was not formed by homogeneous nucleation but by its formation on the MgO particles originated from oxide shell of the Mg particles. When tiny CaO particles were added together with Mg, the particles efficiently transformed to CaS. It was found that Mg-gas helped the distribution of the CaO particles in the hot metal and improved the kinetic condition. Most of the CaO particles smaller than 10 μm were completely transformed to CaS whereas CaO particles >10 μm still had CaO in the center after 20 s. The CaO particles as nuclei were also found to help Mg gas in forming MgS. The ratio of CaO and Mg added was found to have strong impact on the kinetic conditions of desulfurization. This ratio would need further study in any reactor of interest, as the kinetic conditions would differ considerably. The optimized ratio is expected to be a function of the size and geometry of the reactor, the position and the depth of the addition, the manner of addition and more. The hot metal desulfurization mechanisms using Mg and Mg-CaO mixtures were studied. Most added Mg quickly escaped in 2 s. MgS was not formed by homogeneous nucleation but by formation on oxide particles. When tiny CaO particles were added together with Mg, Mg-gas helped distribution of CaO particles in hot metal and improved kinetics. Most CaO particles sized <10 μm were completely transformed to CaS whereas CaO particles >10 μm still had CaO in the center after 20 s.
  •  
43.
  • Lindström, David, et al. (author)
  • Study on the Possibility of Using ZnO for Hot Metal Desulfurization
  • 2013
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 84:5, s. 419-425
  • Journal article (peer-reviewed)abstract
    • The possibility of using ZnO for desulfurization in hot metal was evaluated. A lab scale experimental setup was designed so that different desulfurizing agents could be added to hot metal for evaluation of their desulfurizing power. The setup had good control of both temperature and the gaseous atmosphere. It also provided stirring of the metal bath with an impeller as well as quenching facility to maintain the metal composition at high temperature. Desulfurization of hot metal using CaO powder showed evidently the applicability of the new setup. On the other hand, additions of ZnO into the hot metal under various experimental conditions showed no effect on desulfurization. The results were in contradiction to the suggestion found in literature. A thorough examination of the thermodynamic data employed by the previous work was carried out. The data used in the literature were found to be subjected to fundamental mistakes. The present experimental results convincingly rule out the possibility of using ZnO as a desulfurization agent.
  •  
44.
  • Lindström, David, et al. (author)
  • Study on the Possibility of Using ZnO to Increase the Desulfurization Potential of Blast Furnace Slag and Sulfide Capacities
  • 2013
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 84:1, s. 48-55
  • Journal article (peer-reviewed)abstract
    • Zinc oxide has recently been suggested to be a potential material for hot metal desulfurization. The present work was carried out to examine whether ZnO could help the remaining blast furnace (BF) slag to capture sulfur. For this purpose, slags prepared with relatively high ZnO content was equilibrated with either liquid silver or liquid copper under controlled oxygen potential at 1773?K. It was found that most of the ZnO escaped during the experiment, indicating thereby that ZnO could not increase the desulfurization potential of the BF slag in the case of hot metal. The experimental data were used to evaluate the sulfide capacities of the studied slags. In some of the slags equilibrated with silver, the MgO activities were evaluated.
  •  
45.
  • Lindvall, M., et al. (author)
  • Possibility of Selective Oxidation of Vanadium from Iron and Phosphorus in Fe-V-P Melt
  • 2010
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 81:2, s. 105-111
  • Journal article (peer-reviewed)abstract
    • Experiments on a vanadium recovery method from vanadium containing BOF-slag using both a Tamman furnace (3 kg scale) and an induction furnace (150 kg scale) were conducted. The vanadium was extracted into the slag phase by bubbling oxidation gas into a metal bath consisting mainly of V (1-10 mass%), Si (less than 1 mass%) and P (about 1 mass%). The first experiments revealed that the slag formed during oxidation reaction had considerably high phosphate capacity High phosphorus content would rule out the possibility of using the slag as a raw material for the production of ferrovanadium of high quality In order to reduce the P-content in the slag, addition of slag former to reduce phosphate capacity was necessary. A suitable slag system (having the initial composition 40 mass% Al2O3 - 25 mass% CaO - 35 mass% SiO2) and a suitable atmosphere, by using CO2, that enhanced the oxidation of vanadium, but limit the oxidation of iron and phosphorus was found. However, more efforts should be put forward, e.g. study of the phase diagram, the viscosity of the slag and even oxide activities to gain more insight into the slag formed by selective oxidation.
  •  
46.
  • Muhmood, Luckman (author)
  • A New Insight to Interfacial Phenomena Occurring at Slag-Metal Interfaces
  • 2011
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 82:12, s. 1375-1384
  • Journal article (peer-reviewed)abstract
    • Interfacial dilatational modulus was evaluated for slag-metal systems using oxygen and sulfur as tracers at 1823?K. The high values of the dilatational modulus (510 times that obtained for surfactant adsorption) was directly related to the higher change in apparent interfacial tension prevailing at the slag-metal interface. The variation in the dilatational modulus was attributed to the non-uniform distribution of surface active elements at the interface and also due to the varying surface pressure. Further, experiments were designed to estimate the surface shear viscosity. A relationship was established to find the surface/interfacial shear viscosity from the Newton's law of viscosity. The order of magnitude of the interfacial shear viscosity at the slag-metal interface was estimated from the values obtained earlier for the interfacial velocity. The order of magnitude obtained for slag-metal systems was roughly 10100 times that usually occurring in colloidal systems. The same could be attributed to the high bulk viscosities of the individual phases in slag-metal systems. The order of magnitude of the interfacial velocity was verified from the equation generated earlier by dimension analysis to be similar to those obtained from experiments.
  •  
47.
  • Naraghi, Reza, et al. (author)
  • Spontaneous and Deformation-Induced Martensite in Austenitic Stainless Steels with Different Stability
  • 2011
  • In: STEEL RES INT. - : Wiley. - 1611-3683. ; 82:4, s. 337-345
  • Journal article (peer-reviewed)abstract
    • The fraction and microstructure of spontaneous and deformation-induced martensite in three austenitic stainless steels with different austenite stability have been investigated. Samples were quenched in brine followed by cooling in liquid nitrogen or plastically deformed by uniaxial tensile testing at different initial temperatures. In-situ ferritescope measurements of the martensite fraction was conducted during tensile testing and complemented with ex-situ X-ray diffractometry. The microstructures of quenched and deformed samples were examined using light optical microscopy and electron backscattered diffraction. It was found that annealing twins in austenite are effective nucleation sites for spontaneous alpha'-martensite, while deformation-induced alpha'-martensite mainly formed within parallel shear-bands. The alpha'-martensite formed has an orientation relationship near the Kurdjumov-Sachs (K-S) relation with the parent austenite phase even at high plastic strains, and adjacent alpha'-martensite variants were mainly twin related (< 111 > 60 degrees or Sigma 3).
  •  
48.
  • Ni, Peiyuan, et al. (author)
  • Simulations of the LadleTeeming Process and Verification With Pilot Experiment
  • 2013
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 84:3, s. 276-287
  • Journal article (peer-reviewed)abstract
    • The ladle teeming process was investigated by 2D axis-symmetrical mathematical models and a pilot-plant experiment. Different turbulence models, including the low Reynolds number k-epsilon model and the realizable k-epsilon model both with an enhanced wall treatment (EWT) and a standard wall function (SWF), were used to simulate this process. All of these turbulence model predictions generally agreed well with the experimental results. The velocity distributions in the nozzle were also predicted by these turbulence models. At the late stage of the teeming process, the drain sink flow phenomenon was studied. The combination of an inclined ladle bottom and a gradually expanding nozzle was found to be an effective way to alleviate a drain sink flow.
  •  
49.
  • Persson, Fredrik, et al. (author)
  • Oxidation of Water Atomized Metal Powders
  • 2014
  • In: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 85:12, s. 1629-1638
  • Journal article (peer-reviewed)abstract
    • This study focuses on the oxidation of water atomized metal powders. Pilot plant experiments were performed using liquid iron alloyed with manganese and carbon. The powder particle shape and the oxides were determined using optical and scanning electron microscopy with energy dispersive X-ray microanalysis. The oxygen in the atomized powders was mainly present as thin surface oxide layers, which were determined to increase from 10 to 40-60 nm, at increased particle sizes from 10 to 750 mu m. In addition, manganese oxides were observed to be unevenly distributed at the surface of several particles for iron powders alloyed with 0.3mass% Mn. Experimental data indicated that between 10 and 20% of the manganese was present as oxides in the powders. However, equilibrium calculations predicted a strong driving force for oxidation of manganese. More specifically, it was estimated that only 4% of the initial manganese content remained in the final atomized powders.
  •  
50.
  • Ragnarsson, Lars, et al. (author)
  • Inclusions Generated during Ingot Casting of Tool Steel
  • 2010
  • In: STEEL RESEARCH INTERNATIONAL. - : Wiley. - 1611-3683 .- 1869-344X. ; 81:1, s. 40-47
  • Journal article (peer-reviewed)abstract
    • An industrial trial study was carried out at Uddeholm Tooling AB, Sweden, to investigate the mechanisms of the formation of inclusions, especially macro inclusions during ingot casting. Strong evidence of reoxidation was observed. Two types of inclusions generated during casting were detected in the ingot. Inclusions of Type C1 originated from mould powder with reoxidation product Al2O3 as a part of it. Inclusions of this type were usually small. The number of Type C1 inclusions increased from the centre of the ingot toward the side wall of the mould. Type C2 inclusions were macro size. They could be the results of reoxidation and erosion of runner.
  •  
Skapa referenser, mejla, bekava och länka
  • Result 1-50 of 79
Type of publication
journal article (77)
research review (2)
Type of content
peer-reviewed (77)
other academic/artistic (2)
Author/Editor
Sichen, Du (17)
Jönsson, Pär (13)
Jönsson, Pär G. (11)
Seetharaman, Seshadr ... (9)
Tilliander, Anders (9)
Karasev, Andrey (7)
show more...
Teng, Lidong (6)
Björkman, Bo (6)
Engström, Fredrik (5)
Ersson, Mikael (4)
Doostmohammadi, Hami ... (3)
Jonsson, Lage T. I. (3)
Lindström, David (3)
Adolfsson, Daniel (2)
Robinson, Ryan (2)
Matsushita, Taishi (2)
Jonsson, Lage, 1949- (2)
Du, Sichen (2)
Samuelsson, Caisa (2)
Melander, Arne (2)
Yang, Yang (1)
Yu, J. (1)
Grinder, Olle (1)
Parker, G. (1)
Pettersson, Jean (1)
Ye, G (1)
Wang, Chuan (1)
Ricci, E. (1)
PETTERSSON, R (1)
Ahmed, Hesham (1)
Viswanathan, Nurni (1)
Larsson, Mikael (1)
Aune, Ragnhild E. (1)
Sandström, Åke (1)
Albertsson, Galina (1)
Sundelin, B (1)
Persson, Fredrik (1)
Allertz, Carl (1)
Kojola, Niklas (1)
Hui, Wang (1)
Selleby, Malin (1)
Bergström, Jens, 195 ... (1)
Sandström, Rolf (1)
Eliasson, Anders (1)
Andersson, Margareta (1)
Andersson, Nils (1)
Andersson, Nils Å. I ... (1)
Kapilashrami, A. (1)
Hedström, Peter (1)
Görnerup, Mårten (1)
show less...
University
Royal Institute of Technology (70)
RISE (12)
Luleå University of Technology (7)
Jönköping University (2)
Uppsala University (1)
Karlstad University (1)
show more...
Högskolan Dalarna (1)
show less...
Language
English (79)
Research subject (UKÄ/SCB)
Engineering and Technology (75)

Year

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Close

Copy and save the link in order to return to this view