Bernhard Voraberger, Primetals Technologies Austria, Austria

Co-Author:
Hagen Fuchs, Primetals Technologies Germany
Naci Arun, Primetals Technologies Germany
Gerald Wimmer, Primetals Technologies Austria
Tilo Schulz, Primetals Technologies Austria
Willi Bühler, Primetals Technologies Germany
Andreas Viertauer, Primetals Technologies Austria

Abstract:
"The majority of worldwide steel production is still dominated by the integrated route via blast furnace (BF) and basic oxygen furnace (BOF). Due to rising costs for CO2 emissions as well as rising market requirements for green steel, the integrated steel plants are under pressure to reduce CO2 emissions drastically. The fact that the optimization potential for the coke-based blast furnace is limited, alternatives like increased scrap rate in BOF and especially DRI / scrap based electric steelmaking, which have a considerably lower CO2 footprint, are in the focus for green transition of the steel industry. The integration of an EAF into a brownfield plant is already challenging in respect to e.g. layout, logistics, productivity and environmental aspects; however, the fact that there are fundamental changes to the steelmaking and secondary metallurgy processes is often overseen. In this paper the differences between the two steel production routes via BOF and EAF including corresponding secondary metallurgy are described and compared regarding tramp elements (Cu, Sn etc.) as well as impurities (P, S, N). Limits, challenges and solutions for both routes will be explained for different charge mixes and final steel grade requirements. Special focus is given to demanding steel grades (IF, Si-grades, ULC automotive exposed) which have been mainly produced by converter steelmaking in the past and an outlook is given how to produce these grades via the EAF route in future. Finally recent references for secondary metallurgy will be presented."

Murat Günerdi, Çolakoglu Metalurji A.S., Turkey

Co-Author:
Andreas Fischer, Primetals Technologies Germany
Talip Kücük, Çolakoğlu Metalurji A.Ş.
Burhan Gündogan, Çolakoğlu Metalurji A.Ş.
Dincer Demircioglu, Çolakoğlu Metalurji A.Ş.
Naci Arun, Primetals Technologies Germany
Zafer Cetin, Primetals Technologies Germany

Abstract:
"As the request for ultra low carbon (ULC) steel and stainless steel is rising in the Turkish market, Colakoglu Metalurji A.S decided to increase the production capability for mentioned steel grades. Accordingly, the 300 tons capacity vacuum degassing (VD) plant was modernized by Primetals Technologies in 2020. In this paper, the modernization of the VD plant to the world's largest capacity vacuum oxygen degassing (VOD) plant will be explained. The 304L stainless steel production process and encountered problems with new equipment commissioned, updates of the automation and the level 2 systems will be described. As a result of this modernization work, the production of 304L was performed successfully in the VOD plant. The highest stainless steel heat size with 294 tons and the lowest Carbon level of 5 ppm in the world were achieved with the developed metallurgical patterns during the commissioning of VOD plant."

Barbara Costa Braga, Vallourec, United States

Co-Author:
Aurelien Fabas, Vallourec
Charles Delvaux, Vallourec
Michael Kan, Vallourec
Andre Assis, Vallourec

Abstract:
Steel cleanliness has become increasingly important throughout the years, bringing steelmaker’s attention to operational parameters that can optimize and fulfill these quality requirements. Argon stirring at the LMF is one of the key steps on achieving optimized steel cleanliness, especially if rinsing is performed before CaSi addition (pre-rinse). Trials were performed at Vallourec Star (Youngstown-Ohio) and heats were produced in 2 different scenarios: with and without pre-rinse. Lollipop samples analyzed on ASPEX demonstrates that pre-rinsed heats presented a strong drop on inclusion density (by -50%) when compared to heats that were not pre-rinsed (inclusion density stable). Pre-rinse practice was standardized at VStar.

Enzo Chiarullo, Tenova S.p.A., Italy

Co-Author:
Enrico Malfa, Tenova S.p.A.
Mattia Bissoli, Tenova S.p.A.
Sergio Porisiensi, Pittini S.p.A.
Marta Guzzon, Tenova S.p.A.
Marco Fulgosi, Pittini S.p.A.

Abstract:
Valorization of LF slag: the Pittini Group tests Tenova's air granulation process S. Porisiensi, M. Fulgosi – Ferriere Nord S.p.A. M.Guzzon, M.Bissoli, E.J.Chiarullo, E. Malfa - Tenova S.p.A. The Pittini Group has historically been active and committed to the reduction and valorization of steelshop residues and, in particular, Ferriere Nord plant in Osoppo was the first in Europe in 2000 to implement the recycling of LF slag by injecting it into EAF in lime replacement. In last two years, the Pittini Group tested, at Acciaierie di Verona and Ferriere Nord sites, an industrial-scale pilot plant for the valorization of the ladle furnace slag through an air granulation process developed and designed by Tenova S.p.A. Tenova developed a methodology for the design of dry slag granulation process based on Computational Fluid Dynamic modelling validated by the laboratory testing in a pilot plant. The present work shows the results of the dry slag granulation industrial testing, performed at Ferriere Nord plant, their consistency with the Tenova methodology in the process design together with validation through testing at laboratory scale pilot plant facility. In addition, the first study for the industrialization of the dry slag granulation process is presented, along with the various opportunities for valorization of the final product.

Alexander Schlemminger, QuantoLux Innovation GmbH, Germany

Abstract:
Energy consumption and refractories wear are the major cost drivers of ladle furnace treatment. In addition to factors such as the composition and temperature of the melt, these main cost factors depend strongly on duration of treatment. Long treatment times in particular, as they are common for extremely low Sulfur grade, can require a reheating of the melt. This is unfavorable in several respects. First of all, there can be no treatment work carried out during reheating. Therefore, the holding time of the melt in the ladle is prolonged. Secondly, compared to the EAF the absence of a foaming slag, leads to an overheating of the slag. This excessively hot slag now radiates a considerable amount of energy into the surrounding area, which downgrades energy efficiency. Thirdly, the very hot slag has a negative effect on especially the slag zone of the refractory lining, which has a particularly negative impact on the refractory service life. Precise process control based on in-situ slag analysis results can reliably avoid reheating and the associated unwanted effects. With the Laser Optical Emission Spectroscopy (Laser OES), an enhancement of the well-established spark OES, the physical homogenization of samples becomes obsolete. Instead, an immense amount of measurements allow a digital homogenization. Slag analysis times reduced by up to 90% allow significantly more slag samples to be taken and analyzed in-situ. Thus, the LF treatment can reach the required degree of desulfurization faster and more safely. In addition, the selection of a narrower process window, closer to the desirable optimum, leads to reduced lime consumption and fewer inclusions in the product. This reduces CO2 emissions and optimizes the use of resources.

Anna Mayrhofer, Primetals Technologies Austria, Austria

Co-Author:
Xuedi Schmoelzer Deng, Primetals Technologies Austria
Thomas Reindl, Primetals Technologies Austria

Abstract:
"In a ladle treatment station or ladle furnace station, calculation of desulfurization, aluminum fading and homogenization is a difficult task due to the dynamic nature of molten steel/slag movement controlled by bottom stirring. In traditional model, those parts are normally calculated separately with individual parameter setting. The traditional way needs a lot of parameter adjustment work for different project, due to different ladle size and plug conditions. In the recent developed level 2 model by Primetals Technologies, the reactions, which are led by kinetic movement of molten steel/slag, are considered as a whole part. The key to the new method is a kinetic model which predicts circulation movement of molten steel/slag with regard to ladle size, plug condition, bottom stirring flow rate and height of steel/slag. The result of the new kinetic model gives on average a more precise prediction of sulfur and aluminum value during treatment."

Nicholas Walla, Purdue University Northwest, United States

Co-Author:
Chenn Zhou, Purdue University Northwest
Steve Ryan, NLMK Indiana
Xipeng Guo, Purdue University Northwest

Abstract:
In this work, a 3D transient Computational Fluid Dynamics (CFD) model is developed to simulate arc heating process in a steel ladle. Three phases, air, slag and steel, are considered using Volume of Fluid (VOF) model. Temperature dependent material property are considered. Two off center slit plugs are placed at bottom of ladle. Discrete Phase Model (DPM) model is used to calculate bubble movement, coalescence and breakup during rising process. Heat transfer including radiation from electric arc to multiphases are modeled. Three electrodes are placed at top of ladle. Electrodes submerge length in slag layer is 3 inches. The channel arc model is employed to calculate the characteristics of electric arc. Al2O3 refractory brick and MgO-C refractory brick are include to calculate the heat loss through refractory wall. Based on the results, the dead zone of fluid flow is identified. Flow induced wall shear stress and multiphase distribution are observed. Temperature evolution in the bulk steel and slag are investigated. Temperature profile on refractory wall are studied. As for validation, temperature historical data is provided by industrial. Temperature measured at 2 ft away from refractory, 1 ft below steel surface and above one of the plug. Simulation shows good agreement on temperature between CFD prediction and industrial measurements.

A .Nicholas Grundy, Thermo-Calc Software AB, Sweden

Co-Author:
Lina Kjellkvist, Thermo-Calc Software AB
Ralf Rettig, Thermo-Calc Software AB

Abstract:
There is currently a distinct trend in AI / ML type simulations of the steelmaking and -refining process. Such approaches can very accurately predict the outcome of steel processing, however there are 2 major drawbacks: 1) They only work well in the limits, within which the algorithms have been trained. 2) They are largely a black-box approach, where cause and effect remain hidden. The alternative approach are physical models, that are based on general principles like conservation of mass, conservation of energy, etc… that hold true far outside the narrow window, inside which steel processing is mostly constrained. This means predictions can be made on what happens when the process leaves this window. While such an event might be rare in a well-controlled industrial environment, it is crucial to know what happens, as the potential damage caused if appropriate action is not taken, can be massive. A further advantage of physical models is that the influence of distinct steps in the processing can be analysed separately, as they need to be explicitly implemented in the physical model. Finally -unlike an AI / ML model, a physical model will also provide information for properties for which no experimental measurements have ever been performed. In this paper, a physical model for steelmaking and -refining is presented, that uses thermodynamic equilibria calculated with Thermo-Calc and the CALPHAD type steel and slag database TCOX12. Reaction kinetics are accounted for using the Effective Equilibrium Reaction Zone (EERZ) model. The model is commercially available as the Process Metallurgy Module within the Thermo-Calc Software package and already being used in academic and commercial research. Some application examples are given and if it shown how simulations can be run, directly using process data stored in a Level 2 system.

Nikolaus Preisser, Montanuniversität Leoben , Austria

Co-Author:
Gerald Klösch, voestalpine Stahl Donawitz GmbH
Julian Cejka, Montanuniversität Leoben
Kathrin Thiele, Montanuniversität Leoben
Susanne Katharina Michelic, Montanuniversität Leoben

Abstract:
The role of non-metallic inclusions has become more prominent with increasing demands on the mechanical properties of modern steels. The control of their amount, size, morphology and chemical composition is the key for producing highly advanced steel grades. Interactions between steel and slag essentially influence inclusion evolution over the production process and, therefore, the final steel cleanness. Recently, research on the role of alkali oxides on inclusion behavior in secondary metallurgical treatments increased, especially controlling inclusion scenarios in very cleanness-sensitive steels. This study analyses inclusion behavior and modification in medium carbon steel in contact with low-basicity pseudo-wollastonitic slags with additional contents of alkali metal oxides. In particular, their capability to remove or affect non-metallic inclusions was analyzed. Thermodynamic calculations showed that adding R2O (R=Li, Na, K) can drastically lower the melting point of the slag. As slag and non-metallic inclusions interact, the particles' chemical composition is influenced. As a result, inclusion deformability improves. High-Temperature Laser Scanning Confocal Microscopy and Tammann Furnace experiments were used to study inclusion evolution through their interaction with slag with different amounts of alkali oxides on a laboratory scale. The inclusion population was compared before and after steel-slag interaction using automated SEM/EDS analysis. Particles modified with the added alkali elements could be observed, as well as a shift in the overall inclusion population. Thermodynamic calculations show significant changes in the liquidus temperature of the modified inclusions and a strong dependency on the ratios of Na2O/Al2O3 and Na2O/SiO2.

Lorenzo Engel Fornasari, Ternium, Brazil

Co-Author:
Ricardo Vieira Regis De Almeida Martins, Ternium
André Costa e Silva, Universidade Federal Fluminense
Bruno Cerchiari, Ternium
Raissa Salgado, Ternium

Abstract:
As market demands and competitiveness increases worldwide, steelplants are constantly adapting and innovating to meet higher quality specifications, reach new market shares and achieve cost reductions. As such changes occur, we see renewal in the Steel Industry and gain room to find unprecedented and/or uncharted issues. It was observed at Ternium Brasil Steelplant the occurrence of Chromium Pick-up unrelated to charged materials (i.e. contamination) in the Ruhrstahl Heraeus Vacuum Degasser (RH) during the treatment of electric steels. The Chromium pick-up occurrences were sufficiently high to surpass the client’s specified residual level. As chromium oxides are present in the RH refractories, the present work aims to evaluate the thermodynamic stability and kinetic mass transfer aspects of MgO, Cr2O3, Al2O3, SiO2 systems in contact with Steel. The results indicated that chromium oxide is not stable in the presence of well deoxidized steels, including non-electric grades. Still, a strong influence of silicon on the chromium pick-up was observed. The thermodynamic analysis indicated that the silicon addition to MgO, Cr2O3, Al2O3 systems creates liquid-phases for the typical temperature ranges of steel treatment. This may impact on the kinetics of refractory wear and dissolution. Furthermore, the analysis indicated the high-silicon content of the electric steels lowers the oxygen potential in steel. Besides, silicon reduces the surface energy between steel and refractories, increasing the latter’s wettability. To control the occurrence of chromium pick-up, mass transfer models were formulated for solute transport in steel and for refractory erosion as rate-limiting steps. The models were then used to optimize both the acceptable charge composition and the RH processing time when refining electric steels with controlled chromium residuals. The introduction of these control measures dramatically reduced the deviations associated with high content of residual chromium in electric steels.

Taesung Kim, Hyundai Steel Co., Korea, Republic of

Co-Author:
Jooho Park, Hyundai Steel Co.
Dong Woon Kim, Hyundai Steel Co.
Geun Ho Park, Hyundai Steel Co.
Joo Hyun Park, Hanyang University

Abstract:
The demands for the cleanliness of steel melts are increasing to improve the mechanical and physical properties of high Si & Al alloyed steels. In the present study, the effect of Si content of steel melts containing 1.5% Al as well as the addition sequence of Si and Al alloy on the characterization of non-metallic inclusions have been investigated. When Si (0.5-3.0%) was added to the melts at 1600°C, SiO2 inclusions were primarily formed and thereafter the area fraction of the inclusions decreased over time. Then, the addition of 1.5% Al to the steel melts containing 0.5-1.0% Si resulted in the formation of Al2O3 clusters due to the high driving force of the Al deoxidation, which is in consistent with the population density function (PDF) analysis with a lognormal distribution. On the other hand, singular type of Al2O3 inclusions were formed when 1.5% Al was added to the 3.0% Si melt because the driving force of the Al deoxidation was relatively low compared to that of Si deoxidation. The PDF analysis for the 3%Si-1.5%Al system showed a fractal distribution, which means that the inclusions are grown by collision mechanism. Alternatively, when 1.5% Al was preferentially added to steel melt, cluster-type Al2O3 inclusions were formed by the strong driving force of the Al deoxidation. The number of cluster-type Al2O3 inclusions decreased over time. When 3.0% Si was subsequently added to the 1.5%Al melt, the singular Al2O3 particles were mainly observed in the steel. Because the addition of Al results in the formation of Al2O3 inclusions in the melts regardless of the alloying sequence and Si content, it is important to float up and to separate the cluster-type Al2O3 inclusions to improve the cleanliness of the high Si & Al alloyed steels.

Shengchao Duan, Hanyang University, Korea, Republic of

Co-Author:
Taesung Kim, Hyundai Steel Co.
Jinhyung Cho, Hyundai Steel Co.
Joohyun Park, Hanyang University

Abstract:
The effect of slag composition on the refining and reoxidation behavior of Si-killed 316L stainless steel during ladle and tundish processes were investigated in an induction furnace equipped with a MgO crucible under high purity Ar atmosphere at 1873 K and 1773 K, respectively. For the ladle refining process, the total oxygen (T.O.) content decreased with increasing the Vee ratio (CaO/SiO2=C/S, 1.0, 1.3, 1.7, and 2.3) of the CaO-SiO2-Al2O3-MgO-CaF2 ladle refining slag, but the effect of CaF2 content (15, 20, 25, and 30 %) on the T.O. can be neglected at high C/S condition. The CaO-SiO2-Al2O3-MgO system liquid inclusions can be found as the C/S < 1.3, while the formation of spinel and MgO inclusions were observed at the C/S > 1.7 for a fixed CaF2 content (10 %). For the tundish metallurgy process, the liquid and SiO2-rich Mn-Si-O system inclusions were found as the liquid steel reacted with rice husk ash (RHA) and RHA-CaO-SiO2. The liquid Mn-Si-Al-O system inclusions were observed as reacted with RHA-CaO-Al2O3 flux. The number density of inclusions increased, decreased, and remained constant with the reaction time when the liquid steel reacted with RHA, RHA-CaO-Al2O3, and RHA-CaO-SiO2 fluxes, respectively. The results indicated that the reoxidation of the liquid steel is aggravated as the RHA was used, whereas the RHA-CaO-Al2O3 can facilitate the removal of the inclusions during the tundish metallurgy process.

Kathrin Thiele, Montanuniversität Leoben , Austria

Co-Author:
Christoph Truschner, voestalpine Stahl GmbH
Christoph Walkner, Montanuniversität Leoben
Sergiu Ilie, voestalpine Stahl GmbH
Roman Rössler, voestalpine Stahl GmbH
Susanne Katharina Michelic, Montanuniversität Leoben

Abstract:
Continuous casting of Al-killed Ti-stabilized ULC steels is still linked to the problem of nozzle clogging. Until today the reason behind this phenomenon is not entirely clarified. One possible cause is the attachment of agglomerated deoxidation products (e.g., Al2O3) to the nozzle wall. Therefore, different tracing techniques are applied to track alumina inclusions and their possible modification over the production route. Besides the direct addition of rare earth elements (e.g., La, Ce) to the melt, a second method, the rare earth element (REE) fingerprint, is also discussed. The present study compares tracing on a laboratory scale with trials in the industry. The experiments in the laboratory were carried out in a resistance-heated Tammann-type furnace since an inert atmosphere can be adjusted, and the production route can be depicted through consecutive alloying additions and continuous sampling. In both cases, Lanthanum or Cerium was added to the melt after the deoxidation with Aluminium. Furthermore, samples were taken during the process to detect the change in morphology of non-metallic inclusions. Differences between the industrial and the laboratory scale appear mainly concerning the cooling conditions, the inclusion size and their amount. Moreover, the possibility of investigating the clogged material in the submerged entry nozzle leads to additional output from the industrial trials. Ti-modified REE-traced alumina inclusions were found in all experiments. Together with the investigation of the clogged material from the industrial trial, it can be suggested that preexisting deoxidation products agglomerate and attach to the nozzle wall. The traced inclusions form heterogeneous microscopic multiphase inclusions in all cases.

Julian Cejka, Montanuniversität Leoben , Austria

Co-Author:
Bernhard Sammer, Montanuniversität Leoben
Nikolaus Preißer, Montanuniversität Leoben
Gerald Klösch, voestalpine Stahl Donawitz GmbH
Susanne Katharina Michelic, Montanuniversität Leoben

Abstract:
The demand for higher scrap rates in European steel plants leads to increased amounts of tramp elements in steels, like copper, molybdenum and tin, and their further enrichment due to lack of possibilities for their removal. While other elements, especially the 16th group of the PSE like oxygen or sulfur, are well investigated, the effect of tramp elements on interfacial properties remain unclear. These phenomena are of high importance for different multiphase processes. While poor wetting of inclusions by steel at refining steps is preferred to transport inclusions from liquid steel to the slag, it can be detrimental in continuous casting due to the increased deposition of inclusions in the submerged entry nozzle and finally resulting in clogging. In this work an industrial medium carbon steel has been alloyed with ultra-pure tramp elements, namely Cu, Mo and Sn. The amounts of these increase gradually from standard-confirm levels up to values supposed to occur in future steel scraps. These samples are studied by means of drop shape analysis to quantify the influence of these impurities on the wetting angle on dense alumina and zirconia plates. With this method temperature and time dependency can be observed. Furthermore, the oxidic substrates and steel droplets are examined by metallography and SEM/EDS after the experiments to determine possible reactions. Thermodynamic calculations using FactSage are additionally applied.

Michael Bernhard, Pohang University of Science and Technology, Korea, Republic of

Co-Author:
Christian Bernhard, Montanuniversität Leoben
Sergiu Ilie, voestalpine Stahl GmbH
Youn-Bae Kang, Pohang University of Science and Technology
Won-Bum Park, Pohang University of Science and Technology

Abstract:
Worldwide steelmaking industry targets a CO2 emission-free production of high-quality steel grades based on hydrogen reduction metallurgy and by using renewable energy sources for melting of recycled scrap in electric arc furnaces (EAF) and electric smelting furnaces (ESF). A serious issue for steelmaking plants in melting scrap materials is the unwanted accumulation of tramp elements in the liquid steel bath, e.g. Cu and Sn. Beside those elements, also other present impurities, e.g. S and P are known to may cause quality problems in continuous casting (CC) process, which is the dominating process to produce flat sheets and long product with an amount of 95 % of the annual steel production. The current status of developing a self-consistent thermodynamic database for tramp elements and impurities in steel is presented. The binary and ternary subsystems were modeled according to the CALPHAD-approach, enabling precise calculations of phase diagrams and thermodynamic properties of multicomponent steel. The Modified Quasichemical Model (MQM) was used to formulate the Gibbs energy of the liquid phase to consider the strong short-range ordering (SRO) tendency in M-S and M-P (M = Fe, Cu, Sn) melts. Ferrite and austenite solid solutions and intermediate phases were treated by the Compound Energy Formalism (CEF). Numerous stoichiometric compounds, e.g. phosphides and higher-order sulfides, were modeled stoichiometrically. In the present study, selected examples are demonstrated, linking the database to an in-house developed heat transfer model for the CC process to predict the solidification progress and possible defect formation, e.g. hot tearing. Furthermore, the database is applied to calculate solid/liquid phase equilibria in the Fe-C-Cu-Sn-S system with respect to liquid metal embrittlement in high-temperature ferrous processing. Finally, future requirements on experimental research and modeling work will be also discussed.

Sailesh Kesavan, Swerim AB, Sweden

Co-Author:
Pooria Jalali, Swerim AB
Hyunjin Yang, Swerim AB
Pavel Ramirez Lopez, Swerim AB

Abstract:
SWERIM’s numerical model for continuous caster has been developed over the last decade through numerous projects. The model can predict the caster behaviour at a level of detail that it replicates industrial caster i.e., digital twin. This digital twin model can be used to optimise caster performance without the risk associated with the plant trials. The manuscript describes the methodology used to study the heat transfer in the continuous casting mould with an intumescent coating. The numerical modelling process starts with compiling a database of caster layout, process data, steel grade, and slag composition etc. A 3D virtual geometry of the industrial caster is built with details such as the SEN, mould with cooling water channels and one strand length after the mould exit. The flow, heat transfer and solidification are solved using Fluent CFD software. The reference case was compared with industrial process data such as shell thickness and cooling water rate through blind tests for validation. The heat transfer coefficient (HTC) of the intumescent coating was obtained from characterisation. The HTC value was patched to the mould walls in the validated reference case and a parametric study based on possible operational window was carried out. The resulting data from the digital twin was used to provide guidelines on the operation range with the intumescent coating to obtain optimal solidification in the final product. Keywords: Heat transfer coefficient, intumescent, slab caster, digital twin, solidification.

Tamara Gusarova, SMS group, Germany

Co-Author:
Stephan Six, SMS group
Arnoud Kamperman, Tata Steel IJmuiden B.V.
Roy Frinking, Tata Steel IJmuiden B.V.

Abstract:
Complaints from end-customers cost more than recycling of defect material produced. Therefore it is important to be sure about the quality of the cast steel material prior selling. Internal quality of cast material can be proved via etching / sulfur print or with the new ultrasound technique developed by SMS group GmbH under the name HD scan. The first industrial HD scan system was installed by Tata Steel IJmuiden in December 2018. Since then Tata Steel and SMS work in close cooperation for further optimization of quality evaluation. Several hundreds of samples were measured in production process, more than a hundred were additionally etched and results compared. In consequence, similarities and differences between etching and ultrasound methods were discussed. Most of the results match, however for some samples (normally steel grade specific) discrepancies were observed. Whereas by etching only one surface layer is analyzed, HD scan provides higher reliability of defect distribution due to volume information. Moreover, sometimes defects like cracks are smashed and hidden by sample preparation prior etching. For some other samples differences in results is a case for further studies. The key question to be considered is – what is the best technique for cast steel quality evaluation in modern digital world? Various measurement results from Tata Steel IJmuiden sample will be presented and discussed, as well as some information from other HD scan customers will be given.

Iori Suetsugu, KROSAKI HARIMA CORPORATION, Japan

Co-Author:
Shunji Sadano, KROSAKI HARIMA CORPORATION
Akira Otsuka, KROSAKI HARIMA CORPORATION
Mamoru Yoshimura, KROSAKI HARIMA CORPORATION
Toshihiro Imahase, KROSAKI HARIMA CORPORATION
Yusuke Yamaguchi, KROSAKI HARIMA CORPORATION

Abstract:
Slide Gate mechanism is used world-wide by steel manufacturers to control the flow of molten steel in the steel making process. However, operation of Slide Gate and replacement of refractories still depend on the experience and skills of the operators. Krosaki Harima Corporation has developed one new slide gate called “R-Gate” having improved mechanism for face pressure loading/unloading along with plate refractory clamping. Its operation is simple that provides labor saving and reduced human intervention. So far, around 174 units of this new slide gate mechanism has been supplied to 23 customers worldwide. Further work is going on to make this R – Gate in automatic mode where the whole system including change of refractories parts will be controlled by a general robot “REX-ROBO”. By putting this system into practical use, it is possible to save the labor and reduced human error under severe environment and achieve customer satisfaction. In this paper, we introduce the results of R-Gate’s contribution to our customers through its features and plate life improvement, and an example of automated operations in refractory replacement by collaboration with R-Gate and Robots. In addition, we introduce our latest technology of R-Gate & REX-ROBO.

Gerhard Ney, Saarstahl AG, Germany

Co-Author:
Dirk Deckers, Saarstahl AG
Steven Fries, Saarstahl AG
Marco Abram, SMS Concast AG
Andre Wildhaber, SMS Concast AG
Luigi Alessio, SMS Concast AG
Steve Münch, SMS Concast AG
Anke Britz, Saarstahl AG
Matheos Czarnynoga, Saarstahl AG
Ralf Thome, Saarstahl AG

Abstract:
The new billet caster S1 at Saarstahl AG Saarstahl is one of the world leading suppliers of long products for demanding steel grades of special bar quality. The product portfolio includes a wide range of unalloyed and high-alloyed steel grades with a carbon content from 0.01 up to 1.0 wt.-%C, which are mainly utilized in the automotive sector. To underline its forefront technology position and to achieve further quality improvements, as well as production flexibility and capacity, Saarstahl ordered a new 5-strand billet caster named “S1” in 2017. Designed by SMS Concast AG, the caster produces 180x180mm2 billets. After the successful commissioning of caster “S0” and revamping of caster “S3”, this is already the third cooperation between both parties on a major caster project since 2005. The caster is equipped with Convex Mould Technology, consecutive stirring in mould (MEMS) and strand (SEMS) position, AirMist soft secondary cooling, Dynamic Mechanical Soft Reduction (D-MSR), automatic deburring, marking and sampling machines, speed and temperature measurements as well as an extended discharge concept including 4 silent turn over cooling beds. Among the technological equipment, the installation of the 12 MSR units, which are comprised by six double modules, must be highlighted. Each reduction roll is capable to apply up to 1000kN of force to ensure intense soft and hard reduction. The optimum steel grade specific reduction pattern are adjusted online automatically based on the process conditions and casting parameter to ensure lowest segregation and porosity levels and therefore highest internal quality. 24 months after awarding the contract to build the new “S1”, the caster had its first cast in November 2019. This paper shall outline the main technological features in detail and reflect the quality results that could already be achieved in standard production after an intensive hot commissioning and testing period.

Julien Berton, Vesuvius Europe, Belgium

Co-Author:
Andrzej Warchal, Vesuvius

Abstract:
Corrosion of zirconia containing refractory is one of the chronic issues that limits the service life of continuous casting nozzles resulting in shortening the casting time. In the present study, various degradation mechanisms of the lime-stabilized zirconia grains are discussed, focusing on microstructural and phase analysis. A classification of corrosion mechanisms is performed based on the phase assemblage and compositions of the reaction products resulting from the chemical interactions between mold-flux slag and zirconia containing refractories. A methodology was developed focusing on an experimental approach, thermodynamic modeling, and materials characterization techniques; this allows the development of new material composition and microstructure used in SEN/SES/MTSP sleeves. Several trials performed in the continuous casting operations demonstrate the benefit of new materials contributing to the longer service life of Vesuvius products generating a longer sequence length for the steelmakers. An industrial example performed in Tenaris Silcotub, Calarasi are given to describe the role of chemistry and fundamentals of chemical interactions between slag and refractory.

Carlo Cascino , SMS Concast AG, Switzerland

Co-Author:
Marco Abram , SMS Concast AG
Andrea Lanari , SMS group
Filippo Verlezza , SMS group

Abstract:
Sustainability and lowest carbon footprint with high productivity are the current and future challenges in the steel industry for the production of long products. The CMT® (Continuous Minimill Technology) process developed by SMS group is an inline endless casting and rolling process designed to reach these goals. A low emissions steelmaking facility supplies liquid steel to a high-speed casting machine directly feeding the rolling mill, eliminating the traditional fossil fuel fired re-heating furnace. The pairing of flat bath continuous scrap melting together with direct rolling of rebar or very compact coils concept drastically reduce up to 70% the overall direct emission on site of greenhouse gases, increasing the environmental sustainability of the CMT. Liquid steel is produced and refined by an advanced steelmaking plant, based on Allcharge® design coupled with AURA® IGBT electronic power modules, ensuring the lowest environmental impact in terms of CO2 and NOx emissions and opens the door to connection to renewable power. As the CMT concepts require high casting speed, special attention must be paid to mold and strand guiding design (SMS Concast CONREX technology), mold oscillation (SMS Concast CONDRIVE® electromechanical oscillation) and secondary cooling. The flexible CMT process can be designed for a wide range of products, from straight rebars to Vertical Compact Coils up to 8 tons (VCC). Integrated L1 and L2 automation systems, managing all production process aspects from the scrap yard logistics to the mill finishing area, as well as covering maintenance of the plant are also a key element to the efficient and cost effective production. This paper will highlight the main environmental advantages of this technology, as well as the various concepts for different range of production.

Alija Vila, Primetals Technologies Austria, Austria

Co-Author:
Michael Riedler, Primetals Technologies Austria
Denijel Burzic, Primetals Technologies Austria

Abstract:
"What if your slab caster production calculation requires three strands? The traditional approach would be to install one two-strand caster plus a single strand caster. Or you go the creative way of a three-strand slab caster. This has been first time ever executed for Tangshan Donghua Iron and Steel Enterprise without losing production capacity and decreasing space requirements compared to conventional machine concepts. The visionary setup of this three-strand slab caster will lead to a yearly production of 4 million tons of premium slabs. While outer strands remain on traditional drive concept the middle strand requires a unique design. Additionally, a special focus lays on the design of the tundish, ensuring stiffness and optimum steel flow over all strands. The 3-strand slab caster will be equipped with the latest casting technology, together with the anti-bulging optimized roller geometry enabling high-speed casting. This paper will present the overall machine and process concept as well as design challenges taken."

Wolfgang Rauter, voestalpine Stahl Donawitz GmbH, Austria

Co-Author:
Michael Riedler, Primetals Technologies Austria
Franz Wimmer, Primetals Technologies Austria
Jürgen Reiter, voestalpine Stahl Donawitz GmbH
Werner Brandl, voestalpine Stahl Donawitz GmbH
Alexander Mair, voestalpine Stahl Donawitz GmbH
Mario Erker, voestalpine Stahl Donawitz GmbH

Abstract:
"The new Bloom CC4 continuous caster in Donawitz, is currently the most modern plant of its kind worldwide and corresponds fully with digitalization and environmental standards. The fully digitalized system allows the finest control of the parameters in terms of purity and microstructure homogeneity and an expansion of the product portfolio to 9% alloy content. Rail steels, tubular steels, steels for cold forming, ball bearing steels, spring steels in ""Super-Clean"" quality are among these. Already the first produced blooms on this caster achieved excellent macroscopic cleanliness reducing rejection rate in rail production. Furthermore the CC4 allows a fully automated production process as well as fully automated manipulation and loading of blooms. The paper will present latest innovations and production processes, implemented at CC4 of voestalpine Stahl Donawitz GmbH and additionally quality results for different formats and steel grades are discussed."

Raul Walter Santagostini, SMS Concast AG, Switzerland

Co-Author:
Marcel Meier, SMS Concast AG
Stephan Feldhaus, SMS Concast AG

Abstract:
The steel industry is constantly under pressure to keep prices competitive and a sustainable high-performance rate. Being competitive could be a tough challenge considering that continuous casting is a well-known process in the steel industry. However, especially for high-quality steel grade producers, it is fundamental to enhance the performance of the different technologies part of the continuous caster to keep the quality standard high and the complete control of the process. The technical paper will focus on the following smart products: • Spray Conditioning Scanner. The Spray Conditioning Scanner allows mapping the performance of every single nozzle of the secondary cooling through a membrane pressure transducer system. • 3D printed nozzle. Nowadays, the new technologies available on the market allow us to explore different manufacturing solutions. • The Automatic Movable Stirrer and the solidification and dynamic cooling model (COOL). Different steel grades require the stirrer in a different position for optimal performance. The combination of the COOL software with the movable stirrer can automatically adjust the stirrer position based on different steel grades. • Deburrer of critical steel grade in conjunction with optical product recognition. The optical recognition system is able to detect the billet and bloom shape. The best result from this technology can be achieved only if the billet or bloom shape is seamless as possible. For this reason, an excellent deburrer performance is essential. • Tundish induction heating. Exceptional steel grades are expensive. The induction heating applied to the tundish can increase the continuous casting plant yield and competitiveness. The above-mentioned smart products will allow for meeting the customer's needs and expectations. More detailed information and test results are part of this publication.

Giovanni Cairoli, SMS Concast AG, Switzerland

Co-Author:
Stephan Feldhaus, SMS Concast AG
Pierpaolo Rivetti, SMS Concast AG
Marco Abram, SMS Concast AG
Zhang Jun, SMS Concast AG
Gang Qian, Jiangyin Xingcheng Special Steel Works Co. Ltd
Yuhui Chen, Jiangyin Xingcheng Special Steel Works Co. Ltd
Xiaohong Xu, Jiangyin Xingcheng Special Steel Works Co. Ltd
Guoqing Xu, Jiangyin Xingcheng Special Steel Works Co. Ltd

Abstract:
In order to drastically reduce carbon dioxide emission and realize carbon neutrality, and fulfill the high demand of materials for the wind turbine market which delivers clean renewable energy, with the aim of producing superior as-cast products with high yield and low energy consumption, Jiangyin Xingcheng Special Steel Works Co. Ltd (part of CITIC Pacific Special Steel Group Co., Ltd.) decided to install a jumbo round bloom caster in their premises in Jiangyin City, P.R. China. The caster has been co-designed, supplied and commissioned by SMS Concast AG (part of SMS Group). It has been put into operation in the last quarter of 2021, with the world’s first cast of Ø1200mm round section on the 13th of December 2021. The section size range goes from Ø800mm to Ø1200mm round sections. Advanced technological packages such as Dynamic Mechanical Soft Reduction, three electromagnetic stirrers and optimized secondary cooling will assure the highest bloom quality required by the demanding product mix. Tailored engineering solutions such as cartridge molds, common MEMS, adjustable Strand- and Final-EMS and chain dummy bar system able to cope with the jumbo formats will allow to have a robust and flexible caster, minimizing downtimes. Electromechanical stopper, hydraulic oscillator, on-line solidification model, L1 and L2 automation are completing the Caster scope of supply in order to achieve a reliable and controlled process. Special design solutions as well as first quality results after Caster commissioning are presented in this publication.