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By Renan Bueno Wojciechowski, Yukio Shigaki

The quality of flat rolling process depends highly on multiple factors such as applied forces, materials involved for both strip and rolls, roll geometry and its positioning. To calculate the strip shape, a mathematical/numerical model can be applied, showing the final product and how the equipment behaves when changing some parameters. This is usually a time-consuming task for both user and computer, especially when it involves thin and hard strips. By coupling a quick rolling load calculation method as Bland-Ford and Finite Element Method (FEM) for roll stack deformation, it is possible to create an accurate and user-friendly rolling simulator. This paper presents the improvements done in the 3D FEM/multi-slab method and its actual capabilities by simulating two cases of a 6-High rolling mill. Different analysis in this equipment can be easily done in about 10 minutes by using the developed an electronic spreadsheet program interface and the folder generated with relevant results and logs. An operation manual and a commercial FE program plugins were made to aid construction of a completely new model. The code was created in a modularized way to assist the application of this simulator for other operational conditions.

Oct 1, 2019

By José Aparecido Pereira

The customer asked for a 5” angle roll pass design. For this angle, in a normal pass design, a 160mm billet is required. For the production of this billet would be necessary a new 160mm mold for the Continuous Casting Machine, which produces 150mm billets, increasing the complexity of the melt shop. The rolling mill is designed to produce angles up to 4", technical information recommended the replacement of a gearbox because this process would generate torque up to 15% above nominal. An innovative roll pass design was done using 150mm billet using the Aparecido-W Method that cause a higher spread in the first three passes, thus reaching the desired leg length. As this method is not used in any other known rolling mill, a FES (Finite Element Simulation) and FEM (Finite Element Modeling) was done by a Research & Development center which demonstrated that the design was viable. From July, 2018, three tests were done being produced around 700 t of good quality products without difficulty of set up. The rolling mill team carried out this project at a very low cost and in record time of five months. The average torque of the motors was 36%, without overload for the equipment.

Oct 1, 2019

By Rogério Martins Pereira, Charles Pierri de Souza, Lucas Gabriel Correa

The Tandem Cold Mill is composed by stands with rolls positioned so that the rolling force can be transmitted to the strip being processed. Due to the mechanical stresses inherent in the process, the roll bearings are heated and are equipped with lubrication and cooling systems. Nevertheless, there is the challenge of continuously monitoring the temperature of the bearings, which would allow preventive intervention in case of overheating. This paper presents an in-house solution to temperature measuring system applied to the backup roll bearings of a continuous Tandem Cold Mill. The system uses Zigbee technology and is integrated with the main control system, allowing early diagnosis of bearing heating and proper intervention. Results and features of the system are discussed.

Oct 1, 2019

By Luis Acainas Caballero, Karl Hoen, Stephan Krämer, Christoph Klein

The situation of the steel industry is still challenging. Worldwide overcapacities have an impact on profitability. More than ever, the point at SMS group is to provide the steel industry with flexible and profitable technologies and systems over the whole process chain. One example for that is the thin slab casting and rolling technology and, in particular the CSP® technology (Compact Strip Production), being well established for hot coil production. From its introduction in 1989, CSP® technology has been continuously further developed. Today, on a CSP® plant, the full range of high-quality steel grades can be produced with tightest geometrical and metallurgical tolerances under optimal economic conditions. With the introduction of semi-endless rolling and, as a further step, the endless rolling process, the product range for thin and ultra-thin products has been further enlarged, allowing for the production of hot rolled coils with a thickness of 0.8 mm for low carbon steel grades. Also high-strength steel grades may be produced with gauges below the minimum product thickness that can be achieved in a conventional-type hot rolling mill. Another step in the further development of CSP® technology is digitalization. In December 2016, the CSP® plant of Big River Steel (BRS), located in Arkansas, USA was put into operation. It is the first learning steel mill in the world. The CSP® plant of BRS comes with innovative technologies, providing impressive operational results right from the beginning.

Oct 1, 2019

By Michael Windhager, Karl H. Ziehenberger

ULTIMA® are high performance, centrifugal cast, double poured (CC duplex) work rolls. This paper describes the principle of the ULTIMA® roll concept and its wide range of usability. The ULTIMA® concept provides a solution for rod and bar mills to increase performance and output, even under harsh rolling conditions. The main focus is on highly loaded mill stands that require both high wear resistance and resistance against thermal fatigue, like pre-dog bone, dog bone, slitter. Specific case studies of quite different mill configurations and rolled product mix prove the positive impact on production yield, mill and roll shop operations, and profitability in terms of TCO (total cost of ownership).

Oct 1, 2019

By Edilson Alves Maranhão, Willi Anton Buehler, Andrea Pezza

O processo de vácuo é a solução típica aplicada quando é hora de atualizar o nível de qualidade do aço de uma aciaria existente. A instalação do novo Tanque de Desgaseificação à Vácuo (VD) de 135t no Canadá e do novo RH de 150t na planta integrada no México para a produção de tubos de alta qualidade na América do Norte é um exemplo típico disso. A nova instalação inclui o mais recente conceito de design para este tipo de equipamento: operações totalmente automatizadas e menor impacto ambiental são os principais aspectos do projeto. A solução de bomba mecânica a seco continua sendo a melhor abordagem de investimento e custo operacional para a tecnologia de vácuo. Os principais aspectos do design da planta são descritos neste documento. O desgaseificador a vácuo VD é responsável pela melhoria das performances metalúrgicas, especialmente em termos de nitrogênio, remoção de hidrogênio e nível de pureza do aço. O processo a jusante e os resultados estão estritamente ligados aos desempenhos do desgaseificador a vácuo. O monitoramento de processos através da linha completa é uma prática padrão para obter uma melhoria efetiva da qualidade do produto. Os desempenhos metalúrgicos do desgaseificador a vácuo VD são analisados e comentados neste trabalho.

Oct 1, 2019

By José Roberto de Olveira, Anna Paula Littig Berger, Caio Vaccari Silva, Victor Bridi Telles, Felipe Fardin Grillo, José Roberto de Oliveira

No presente trabalho foi proposto uma análise da eficiência de desfosforação de uma mistura padrão M1 e outras cinco misturas, onde foi realizada variação da massa de mistura adicionada ao sistema (60,70 e 80g), temperatura de trabalho (1350ºC e 1350ºC ajustada) e metodologia de adição. Os testes experimentais foram realizados a uma temperatura de 1400°C, com agitação de 450 RPM, em um forno de resistência. Para a análise das propriedades da escória, foram realizadas simulações através do software de termodinâmica computacional FactSage 7.2 e análises de imagens obtidas da superfície do cadinho ao final dos experimentos no software Quantikov. A mistura M1 apresentou melhor desempenho do que as misturas em todas as situações estudadas, sendo observado que melhores condições experimentais foram a utilização de 70g de mistura, a uma temperatura de 1400ºC, com a metodologia padrão de adição de toda a massa da mistura no início do experimento.

Oct 1, 2019

By Daniel Andrade Paes de Lima, Gerson Evaristo de Paula Júnior, Beatriz Fausta Gandra

The gradual reduction of the sinter feed size has been a complicating factor in the maintenance of sintering productivity. In addition, pellet feeds have been used for chemical correction. Because of this, it is necessary an effective cold agglomeration step in sintering to keep the ironmaking competitiveness. Thus, in the present paper, four different technological routes for cold agglomeration with sinter feeds (drum mixer, intensive mixer + drum, double drum and HPS - Hybrid Pelletized Sinter) were evaluated in pilot scale and their impacts on the indicators of the sintering and the sinter quality was obtained. It was found that the best results on granulation index and, consequently, productivity were obtained in the route using HPS. However, the sinter from this process was the most fragile among the analyzed ones. The performance of the double drum process was superior to the intensive mixer from the point of view of productivity and sinter quality.

Oct 1, 2019

By Gabriel Andrade Medeiros, Christian Brugger, Paul Pennerstorfer, Daniel Fuchshuber, Reinhold Leitnerl

State-of-the-art automation technology enables digitalization of the continuous casting process that goes far beyond conventional automation of industrial production. Primetals Technologies provides a digital twin that combines an intelligent digital representation of a casting machine as well as the casting process and the slabs, blooms or billets that are produced. It allows metallurgists and process engineers to predict the behavior of the involved complex production process and optimize parameters before using them in real production. New steel grades or production processes can be evaluated off-line without any risks to process stability and product quality. Primetals Technologies installs the digital twin with every new installation of a continuous caster optimization system. This paper describes how the setup and simulation possibilities of the digital twin provide numerous benefits by modelling and simulating the casting process. It allows for example the calculation of material properties according to the actual composition, strand surface temperature profiles and dynamic soft reduction before the final point of solidification. An outstanding feature of the digital twin is the replay functionality provided for various models to analyze and further optimize real production situations. The paper also gives an example how usage of the digital twin optimized production at a customer.

Oct 1, 2019

By Gilberto Fernandes Lima, Leonardo Neves, Getúlio Fonseca dos Santos

O refino secundário é um processo onde a homogeneização do aço e as flotações de inclusões ocorrem no banho metálico, cujo conhecimento do tempo de mistura é necessário na produção de aços limpos. A panela, principal vaso onde ocorre o processo, contem plugues ou bicos de injeção de gás inerte, podendo ser utilizados argônio ou nitrogênio, que são responsáveis pela rinsagem do aço. Devido à importância desta etapa neste processo, este trabalho objetivou realizar o estudo do escoamento bifásico do aço na panela com duas configurações diferentes, sendo a configuração um com dois plugues de gás inerte: ambos a meio raio e a configuração dois com dois plugues de gás inerte, um a meio raio e outro no centro da panela. Neste projeto foi utilizada fluidodinâmica computacional, CFD, para a realização das malhas e simulações que forneceram as curvas de traçador e o perfil de velocidade para ambas as configurações. Os resultados simulados indicam que a configuração dois é a mais indicada para o escoamento bifásico, sendo a melhor opção para ser utilizada no modelo de panela industrial.

Oct 1, 2019

By George Schipper, Peter Gelten, Pepijn Adriaen, Hugo Uijtdebroeks

Tata Steel IJmuiden Hot Strip Mill 2 (HSM2, 5.5 Mtonnes/yr) is currently being upgraded, resulting in an increased rolling force and motor power capacity. With the current conventional work roll spray cooling, a deterioration in work roll & strip surface quality performance is expected as a result of the increased mill capacities. In order to improve strip surface quality, HSM2 decided to do a full-scale production trial with High Turbulence Roll Cooling (HTRC) at stand FM2. HTRC is a novel way of roll cooling using a high turbulent flow regime. HTRC is positioned very close to the roll surface and gap exit, which is beneficial for the roll surface quality. It is operated at a high flow rate but at a low pressure. HTRC not only significantly improves the roll surface quality, in addition, it makes high pressure pumps, needed for the conventional spray cooling, redundant, leading to substantial savings on electricity costs and thus CO2 emissions. HTRC is in trial operation since 7 August 2018. Results show no operational issues, an excellent roll surface quality and an increased cooling efficiency. In summer 2020 stands FM1-FM2-FM3-FM4 of HSM2 will be equipped with HTRC.

Oct 1, 2019

By Edmar de Souza Silva, Antonio Augusto Gorni, Emanuelle Garcia Reis, Daniel Bojikian Matsubara

Controlled rolling followed by accelerated cooling, known worldwide as TMCP, aims to increase mechanical properties without toughness deterioration. The process principle is to promote the plate cooling with water jets along the range of the austenite transformation temperatures. The accelerated cooling process is only fully effective when controlled in an integrated manner, as it alone cannot ensure significant improvements in the final properties of steels. Plate surface quality depends on some parameters that must be controlled before the start of the plate accelerated cooling. Good flatness is essential to avoid irregular water accumulations during cooling. After the reheating process, the slab should have uniform temperature, uniform austenitic grain size and easily removable scale. The slab thermal and microstructural heterogeneities are inherited by the rolled plate and tend to increase further during the accelerated cooling. This results in flatness problems, high level of internal stresses and mechanical property variations. The descaling strategy is an extremely important factor and must be determined with great caution. It is important that scale thickness and distribution is uniform to ensure homogeneous cooling over the entire plate surface. Otherwise, there will be an uneven temperature distribution, which can cause serious problems of flatness, surface quality and mechanical properties.

Oct 1, 2019

By Helênio Resende Silva Júnior, Thiago de Oliveira Mazzeu

O envelhecimento gradual das Baterias de Coque é um fato inevitável, sendo importante monitorar as condições dos fornos e das estruturas periféricas para maximizar sua vida útil. A Paul Wurth desenvolveu uma metodologia de diagnose que avalia as condições dos elementos principais que compõem as plantas de Coqueria, dentre elas: estrutura da alvenaria refratária, estruturas e componentes metálicos, análise do controle térmico e regime de pressões, conjunto das máquinas móveis. Através de inspeções visuais e coleta de informações de processo e rotina adotada pela equipe de preservação da planta de Coqueria, são elaborados procedimentos e recomendações que visam à extensão da vida útil do equipamento. A Diagnose é uma técnica que auxilia as equipes de Coqueria a entenderem em que situação o equipamento se encontra e contribui com as melhores práticas adotadas no mercado para o prolongamento da vida útil. Ela deve ser repetida com frequência de modo a atualizar a situação da Bateria de Coque, verificar o efeito das ações tomadas pela equipe de preservação e propor novas recomendações. A Diagnose ainda permite identificar a idade real de desgaste das estruturas da Bateria em comparação com sua idade cronológica, permitindo que as usinas planejem investimentos de maior porte.

Oct 1, 2019

By Jean-François Stumper, Mario Moser, Mark Kruessmann, Volker Langer, Daniel Bastos Martins Cruz, Claude Meisch

The latest generation of probes and casthouse machines provide a wealth of data that has not been available a few years ago. The evaluation of this data gives direct feedback to improve the blast furnace efficiency, the equipment maintenance and design and it allows the early detection of critical or deviating process situations. A stable operation with lower operation and maintenance costs are the final customer benefits.

Oct 1, 2019

By Marcelo Rebellato, Leonardo Silvestre, Zhang Yongqing, Felipe Bastos, Zhang Weiqiang

This work reviews the new version of GB1499.2-2018 Chinese national standard and specification, which governs the production of high-strength reinforcing hot rolled ribbed bars in China. In addition, it discusses the main concerns from Chinese rebar makers that might affect production and application of Nb-bearing rebars, like reheating temperature required to dissolve given niobium additions, the promotion of bainite microstructure and continuous yielding, as well as Nb strengthening effects. Through extensive investigation involving both thermomechanical laboratory simulations and industrial trial, the existing state and effects of Niobium along the reheating, rolling and cooling are illustrated. At the end, optimum processing conditions have been established to produce high strength rebars for the specified requirements. The adoption of new process conditions reflected in an amount of about 20.0 million tons of Nb-bearing rebar being produced in China in 2018 with required tensile properties and microstructure, and helped rebar makers to reduce production costs considerably. Based on production data, Niobium demonstrated positive strengthening effect for high strength rebars, in particular for small diameter rebars with earthquake resistant performance. What is more, the results of the research enrich the knowledge of the application of Niobium in steels when TMCP rolling is not used.

Oct 1, 2019

By Emanuelle Garcia Reis, Gustavo de Sousa, Rodney Pardo Alves

Gerdau Ouro Branco´s plate mill started the operation in 2016 with high level technology. In general, national and international plate markets are every day more rigorous about final product quality. Suppliers must be aware about dimensional accuracy, surface quality and flatness of the plates, independent of the quality standards. To guarantee the best service to this increasingly demanding and competitive market, it is extremely important to guarantee the original project conditions executing the right maintenance of the rolling mill main components. In order to maintain the product quality and avoid the production and maintenance cost increase, it is important to find ways to control the mill and the main process variables, through daily measurements of the equipment performance. This paper aims to present the influence of the main equipment variables that affect the mill operational stability and how to control and evaluate the mill performance.

Oct 1, 2019

By Ludmila Vieira da Silva Matos

O presente artigo investigou como a condição de operação das zonas de resfriamento em máquina de lingotamento de placas contribui para o desempenho de lanças air mist. Tal investigação foi realizada no laboratório da Spraying Systems Brasil a partir das premissas de projeto de uma nova máquina de lingotamento e um novo conceito de lança air mist: menor consumo de ar comprimido, amplo turndown e qualidade de cobertura por toda a curva de operação do resfriamento. As curvas de performance foram montadas para diferentes condições de utilização de ar comprimido: de 1,5 a 4,5bar de pressão constante. Cada lança teve das vazões mínimas às máximas de água ensaiadas. A qualidade do perfil do jato produzido foi verificada para cada ponto das curvas obtidas, em mesa de distribuição no laboratório da Spraying Systems. Com as imagens em mãos, foi possível selecionar aquelas condições de vazão de água e pressão de ar comprimido com melhores perfis de jato e cobertura. Como resultado, a fabricante da máquina pode validar e/ou modificar a curva de trabalho de resfriamento da máquina e garantir as melhores condições do perfil do jato e uniformidade de resfriamento.

Oct 1, 2019

By Chengjia Shang

Aiming at greatly increasing efficiency and saving budget, higher strength and larger-diameter pipes have been developed and applied for constructing long distance pipeline projects in China. At the same time, in order to produce pipeline steel with high strength, high toughness and excellent DWTT performances, it is critical to refine austenite grain by static recrystallization rolling. Therefore, this paper focuses on the brief introduction of development of pipeline projects in China and also on the basics research in the field of static recrystallization during austenite processing of Nb-bearing steel.

Oct 1, 2019

By L. Martins Demuner, D. Burzic, V. Cunha Aranda, F. L. Lourenço, G. Romeu Trindade dos Santos, F. Ramstorfer

For many years, Dynamic Soft Reduction has been regarded as a proper method in improving internal quality of slabs. Even though processes models improved significantly over the past years, the efficiency of Soft Reduction was always limited by the discretization error, which inherently exists if segment rollers cannot be positioned individually. The recently developed SRD segment type allows for an individual roller positioning within the mushy zone by avoiding any discretization deviation from the optimal gap. This paper provides a detailed technological overview of the SRD segments as well as operational results at their very first implementation at Ternium Brazil.

Oct 1, 2019

By Andrea Codutti, Gianni Tiussi, Andrea Tonnicchi, Morris Codarin

Essar Algoma Steel, Canada, awarded Danieli Transimissions a strategic order for the upgrade of the main drive spindles belonging to the most loaded stands of the Hot Strip Mill, F1-F2, F5 and F6. Featuring special heavy duty design and advanced torque monitoring system, these spindles replace existing competitors’ grease lubricated design with the efficient continuous oil lubricated solution to withstand the tough working conditions, increase life expectations and provide room for a product mix extension. The first couple of spindles have been installed in September 2017 by the expert Service team and are showing already good and reliable performance. Progressively all the others are being installed.

Oct 1, 2019