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By Rudolf Lesch

Till date, coke has been produced mainly from coals with a content of volatile matters in the range of 20% to 28% and good coking properties. If such so-called "selfcoking" coals are available, blast furnace coke or foundry coke with the required quality characteristics can be produced in top-charged horizontal ovens. In this case, the possibility of using high-volatile coals and in particular coals with low-caking properties is very restricted. Even if high-volatile coking coals have good coking properties, coke produced from such coal alone will not meet the requirements in terms of coke strength. The mechanical coke properties are influenced by the charge coal blend and the coking conditions. In this context, the bulk density of the oven charge is a decisive factor. Research and development in the field of coke production in horizontal chamber ovens aims at improving the specific oven throughput, increasing the raw material basis and introducing environmental protection technologies. The key factor, however, is to guarantee and further improve the rentability of the coke production. It is very important to reduce the cost of the charge coal to a minimum at the same time maintaining or even improving the coke quality.

Aug 17, 2017

By Stefano Baf

This paper describes the main technical and process solutions applied to the extrathick and wide slab caster built at Yingkou (Liaoning, P.R. of China), as well as all the features required to achieve the surface and internal quality targets.

Aug 16, 2017

By Daniel Eduardo Parodi

Para acompañar el plan de aumento de producción de slabs de Siderar, fue necesario proyectar una nueva unidad separadora de aire para incrementar la generación de oxígeno, nitrógeno y argón. La premisa que direccionó este proyecto fue la integración y sinergia de la nueva unidad con el sistema de la Central Termoeléctrica y Altos Hornos, con el objetivo de salvar condicionamientos, obtener beneficios energéticos y aumentar la confiabilidad operativa. Como resultados de esta línea de trabajo se espera: Optimizar el aprovechamiento de gases de proceso, mejorando así el balance energético y la ecuación económica en la producción de los gases industriales; Mejorar el aspecto ambiental disminuyendo el quemado de gases en antorcha, reduciendo el consumo de combustibles fósiles y la compra de energía eléctrica; y aumentar la confiabilidad en el suministro de gases y del sistema de aire soplado a Altos Hornos.

Sep 25, 2017

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 Emanuele Osto

In late 2013, the installation of the world's first application of a break-through technology for rail hardening was started at Baogang Iron & Steel (Group) Co. Ltd. in Inner Mongolia, China, one of world's leading rail producers. The "Injector Dualphase Rail Hardening" (idRHa+) system was developed by Primetals Technologies and Centro Sviluppo Materiali S.p.A. (RINA-CSM) a Technical Center headquartered in Rome, Italy. Baogang was a key partner, providing its large expertise of premiumrail producer, including its experience with existing offline technologies. With a design based on thermal, mechanical and metallurgical models, idRHa+ can apply customized cooling protocols, so to obtain the desired microstructure and hardness distribution across the rail head, with a high degree of accurateness and operation flexibility. idRHa+ can be installed in inline or offline configurations. During 2014, the system was successfully commissioned at rail mill #2 in the city of Baotou, Inner Mongolia, and entered the regular commercial production. This paper gives an overview of the key concepts behind idRHa+'s design, the progression of its commissioning and testing till the ramp-up to consistent industrial operation. Derived from idRHa+ research and experience, other water-cooling technologies are available for different applications such as: quenching & tempering of medium-large sections, control of distorsion of merchant bars, quenching of stainless grades for improving the resistance to corrosion.

Aug 16, 2017

By Jesús A. Carlos Cornelio

Since their discovery in 1991 Carbon nanotubes (CNTs) have attracted much interest due to their remarkable mechanical, thermal, electrical, chemical and optical properties. In connection with their mechanical properties, CNTs have been studied in various forms for tribological applications including their use as lubricant additives for oil and water. In this paper the tribological properties of CNTs (SWCNTs and MWCNTs) when used as lubricant additives are studied under rolling-sliding conditions in a twin-disc testing machine. The tests were performed using 5% of creepage and pressures of 0.8 GPa and 1.1 GPa. Used functionalized nanotubes were modified with carboxylic acid ultrasonically dispersed at different concentrations (0.01, 0.05%). The results indicated that the presence of carbon nanotubes leads to a decrease in both friction coefficient and wear rate for both systems studied (oil and water).

Jul 31, 2018

By Johanna Alegría-Ortega

Cr/CrN bilayer coating was deposited on AISI 440C by Cathodic Arc. The composition and structure of the Cr/CrN coating were investigated by scanning Electron Microscope, X-Ray Diffraction and X-ray Photoelectron Spectroscopy. The results show that crystal structure obtained was CrN phase with preferred [220] orientation. The hardness and adhesion of coating also were studied. The evaluation of erosion-corrosion (EC) on 440C bare and coated with Cr/CrN was performed by carrying out wear tests using a slurry jet with impingement angle 90° at 4 and 8 m/s. Corrosion, erosion and synergism wear rate were evaluated following the procedure described in ASTM G-119-09. This study presents that the synergism wear rate exceeds 40% of the total mass loss for coating and 60% of mass loss for the 440C, being the most aggressive wear component. The increase in impact velocity generated a rise in mass loss for both 440C bare and coated. The Cr/CrN coating offers better corrosion and erosion–corrosion resistance under all the tested conditions.

Aug 8, 2018

By Johan Richaud

Achieving high surface quality steel in the continuous casting process requires optimal mould level control. The design of the casting channel from the tundish to the mould is crucial to prevent formation of undesired instabilities or biased flows that can cause level fluctuation. With the aid of CFD and with physical water models, the geometry of the stopper nose and the nozzle seat have been studied and optimized to improve the overall mould flow stability. A special stopper nose; Ripple Stopper (RST), has been developed that reduces the formation of large and unwanted eddies in the liquid steel that destabilize the port exiting jets. Instead, the RST produces a fast release of turbulence in the form of a large number of small eddies. The large sudden fluctuations in the mould level are reduced, which in turn reduces the occurrence of surface defects. An additional benefit is derived from the local pressure around the stopper nose region being greater which reduces the refractory erosion. For a tundish gate type flow regulation, a new design encompasses an offset in the Tundish Well Nozzle (TWN) that realigns the flow and reduces the bias flow that is common to tundish gate regulation. The steel recirculation regions below the throttling gate are decreased reducing the risk of oxide depositions. The RST and the Offset bore casting channel have been applied successfully leading to a superior flow control performance between the tundish and the mould.

Jul 30, 2018

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 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 Alessandra Spaghetti

Rolling small-diameter hot wire rods at high speeds with conventional laying head pipes can wear the pipe out frequently and affect quality and consistency in the final product. Laying head upgrades using Sandvik SAF2507LHP™ (UNS S32750) tubes make possible to achieve optimal metallurgical properties, smooth coil formation and easier coil handling. Operators can also avoid unwelcome shutdowns due to frequent worn pipe changes and turndowns. Sandvik have been developing different customers and understand their process needs. The suitable selection materials that are able to withstand high levels of wear better than low alloy and carbon steel grades that are commonly used in industry is very important to improve the quality and increase productivity. UNS S32750 tubes were demonstrably superior to low alloy and carbon steels when used in Laying Head Pipe system regarding tubes lifetime, reducing replacement, production interruptions and increasing reliability.

Aug 17, 2017

By Maurizio Massimo

Danieli developed the “3Q” suite of process control technologies to address three critical principles: delivering the highest product Quality, in the required Quantity, with Quickness of response required for today’s casting machines. Ever increasing market demands for productivity and slab quality necessitate the latest advances/improvements in equipment design, process technology, and control software for all types of slab casters, and Danieli boasts a unique experience that extends from ultra high-speed thin slab casters to extra high-thickness conventional slab casters. The “3Q” system is monitored and controlled by a unique, intelligent HMI incorporating. Touch screen technology and Operator Assistant tablets. Operator Assistant is a tablet based system that guides the operator through the plant process, so that in the event of a process change or an alarm the operator is automatically presented with the choice of possible solutions / actions. The comprehensive range of technological packages cover all aspects of caster design and automation control, from feeding of liquid steel into the tundish to the final slab leaving the caster.

Aug 17, 2017

By Osmar Roberto Bagnato

Este trabalho apresenta um estudo do desgaste de insertos e tensões residuais em diferentes estratégias de entrada de ferramenta no fresamento da liga Ti-6Al-4V. Esta liga possui propriedades mecânicas que a torna ideal para aplicações onde é necessária uma ótima relação resistência-peso. O objetivo é reduzir o desgaste dos insertos no processo de fresamento e analisar as tensões residuais na usinagem da liga Ti-6Al-4V. A integridade superficial do material após a usinagem deve ser conhecida já que esta liga é utilizada em aplicações criticas. Quatro estratégias de entrada foram estudadas, sendo que no faceamento foi utilizada a entrada por rolagem e a frontal reta e no fresamento de cavidade foi utilizado mergulho reto e em rampa. Em todos os ensaios foram utilizados os mesmos parâmetros de usinagem. As tensões residuais foram medidas por difração de raios-X (Luz Sincrotron), pelo método sin²?, utilizando um difratômetro de raios-X instalado no LNLS. No faceamento a estratégia por rolagem mostrou uma importante redução do desgaste e uma pequena redução da tensão residual quando comparada com a estratégia frontal reta. No fresamento de cavidades a estratégia de mergulho reto mostrou um inesperado aumento do desgaste e uma significativa redução da tensão residual quando comparada com o mergulho em rampa. Todas as tensões residuais encontradas foram compressivas. As tensões residuais encontradas em todos os experimentos se mostraram favoráveis a aplicações sujeitas à fadiga.

Aug 8, 2018

By Laurent Dorel, Sebastien Maillard, Afchine Nasserian, Jean-Paul Faure

Surface quality monitoring is primarily implemented in the last steps of steel manufacturing before shipment to the end user. However, an increasing trend for also addressing this topic in the upstream stages, such as hot rolling plant, is tackled by Primetals Technologies to give steel producers the key to a global optimized yield management, and efficient “lessons learned” processes. After the last developments of SIAS Next Gen platform, including High Resolution and Near Infra-Red, some site results will be exposed on the very specific high constraints lines such as ESP Endless Strip Production and Plate Mills, and highlights the related most interesting aspects for our customers.

Oct 1, 2019

By Alexander Fleischanderl

Steel market has become somehow unpredictable and requires quick adjustment in production conditions to survive in the harsh market environment. Steel production is not anymore driven by output records, but by efficient cost reduction measures to remain competitive under strongly varying production conditions. Energy efficient production and flexible raw material scenarios have become decisive factors to succeed and survive in our industry. Such scenarios have to be carefully investigated to be well prepared to adopt production steps continuously. The paper analyses various process opportunities to optimize energy and raw material consumption in the production route. Off-gas treatment systems have still a huge untapped potential to recover energy from the hot waste gases. This is valid for the EAF mini mills as well as for the integrated route. Various examples for waste heat recovery systems including resulting benefits are discussed for the EAF, agglomeration, blast furnace, direct reduction and BOF. New innovative bag-filter systems feature extremely low emission levels at lowest pressure loss and sound emission conditions. Also improved control and automation solutions support the operators to minimize the operation and maintenance costs of their off-gas system. Steelmaking by-products shall not be considered as residues, but as a valuable and cheap raw material source. The paper presents some show cases how to valorize slags as well as utilizing coke and iron oxide fines to increase productivity and minimize raw material cost. A new process for highly flexible converter steelmaking allowing for extraordinary high HBI and scrap rates above 50% and improved yield is discussed and evaluated

Oct 30, 2017

By Jan Lückhoff

The introduction of the EAF Quantum furnace by Primetals Technologies represents an important milestone in the field of electric steelmaking during the last 15 years. In this process the latent and chemical heat of the off-gas generated during a melting process in an EAF is used to pre-heat scrap in an integrated shaft prior the melting of the scrap in the vessel. Combining proven own technologies, Primetals EAF Quantum enables nearly continuous process, cutting down idle times and enhancing availability for production. The essential benefits will be shown in this Paper.

Aug 16, 2017

By Leandro de Arruda Santos

O objetivo deste trabalho é contribuir no desenvolvimento de novas soluções para a terapia endodôntica através do uso da análise por elementos finitos para avaliar o comportamento mecânico de instrumentos endodônticos. Primeiramente comparou-se os resultados de testes de flexão e torção com simulações realizadas sob as mesmas condições para validação. Uma vez validada a metodologia, pôde-se avaliar o comportamento de uma lima de NiTi CM em comparação a outras duas de aço inoxidável e NiTi superelástico com mesma geometria. As geometrias de dois instrumentos endodônticos comercialmente disponíveis foram submetidas a microtomografia computadorizada para a construção de modelos 3D. A malha de elementos finitos em ABAQUS e as condições de contorno foram baseadas em ensaios experimentais de flexão e torção de limas. Os modelos constitutivos foram obtidos a partir de curvas tensão-deformação em fios de NiTi superelástco, NiTi CM e aço inoxidável. Os resultados mostraram uma boa concordância entre resultados experimentais e simulados. O instrumento de NiTi CM apresentou-se como o mais flexível em comparação aos instrumentos de NiTi superelástico e aço inoxidável.

Aug 16, 2017

By Ana Carolina Ribeiro Duarte

Este trabalho teve por objetivo avaliar sistematicamente as etapas do processamento termomecânico de um aço SAE 1070 comercial. O aço foi trefilado a seco por 12 passes consecutivos com reduções médias entre 15% e 21%. A deformação verdadeira acumulada ao final do 12º passe foi de 2,52. Em seguida o material foi recozido a 1000ºC por 10, 20, 30, 60 e 120 min. A caracterização microestrutural foi realizada com o auxílio da técnica de microscopia óptica, microscopia eletrônica de varredura e microscopia de força atômica. A rugosidade do material foi medida via microscopia confocal. O material teve ainda seu comportamento mecânico avaliado por meio de ensaio de dureza Vickers. Os fios de aço apresentaram a estrutura “curling” após o processo de trefilação. Essa estrutura foi substituída por uma estrutura perlítica refinada quando o material foi submetido ao recozimento. O ensaio de microdureza mostrou que, para restaurar as propriedades mecânicas do material, um recozimento entre 20 e 30 min seria suficiente. A análise da topografia revelou que o processo de trefilação altera consideravelmente a rugosidade do material.

Aug 8, 2018

By Gustavo Tressia

Neste trabalho foi avaliada a influência da geometria da câmara de acumulação e da relação de extrusão na fabricação de fios de cobre por meio do processo de conformação contínua, Conform. Dois tipos de produtos foram fabricados, sendo um retangular com menor área de seção transversal e outro redondo com maior área. Para a condição do material redondo, dois tipos de câmara de acumulação foram utilizados, sendo uma de maior dimensão, resultando em maior acumulo de material antes da conformação pela matriz de extrusão. Medições de temperatura foram realizadas na matriz de extrusão. No produto final foram realizados ensaios de limite de resistência à tração, escoamento e alongamento. Ao longo da câmara de acumulação e no produto final foi realizada analise microestrutural e de tamanho de grão. Os resultados mostraram que o aumento da relação de extrusão promoveu aumento da temperatura do conjunto e consecutivamente aumento do tamanho de grão do produto final. Ao longo da câmara de acumulação foi observada uma tendência de redução do tamanho de grão até o produto de saída.

Oct 30, 2017

By Leonardo Sales Araujo

Ligas de zircônio encontram grande aplicação em componentes estruturais do núcleo de reatores nucleares, dadas suas vantagens como resistência mecânica e a corrosão e baixa seção de choque de nêutrons térmicos. Contudo, por se tratar de uma liga reativa e necessitar de homogeneidade química e microestrutural, requer processos de fusão especiais como refusão a arco em vácuo. No presente trabalho, foi produzido um lingote de liga de zircônio a partir de briquetes de zircônio esponja compactados e unidos por soldagem para a composição do eletrodo. Foram realizadas duas refusões para aumento do tamanho do lingote e aumento da sua limpeza. As duas fusões foram analisadas por meio de observação das variáveis de processo. Foi possivel corroborar a viabilidade do processo de fabricação do lingote de zircônio em duas etapas de refusão. A análise das variáveis de processo mostrou que a primeira etapa de refusão apresentou maior instabilidade durante a fusão, o que poderia afetar a estrutura de solidificação. Com isso, uma etapa de refusão foi realizada, com maior estabilidade, além de potencialmente propiciar maior grau de limpeza e homogeneidade da liga.

Aug 16, 2017