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By Thomas Schanz

Current steel market conditions require small investments only to lower operational cost. SMS Concast has developed new products which optimize continuous casting process cost for long product steel production. This paper describes a selection of three products. All three systems are patented (patent pending for CONDRIVE). CONSAFE, a non-radioactive mould level measurement system for reliable mould level measuring on open stream casting CCM’s; CONSTIR-MWS, an improved control software for electromagnetic stirrers which lowers energy cost by 35%; CONDRIVE, a brand new oscillation drive system which provides the features of a hydraulic oscillator, however with a cost efficient electric drive.

Aug 17, 2017

By Breno Delgado Silva

O conceito de Fast Track é a retirada das manutenções leves de dentro de oficina, migrando-as para realização em pátios, enquanto os vagões ainda estão no trem. A mudança de estratégia de manutenção para englobar este conceito aumenta o espaço disponível nas oficinas para realização de reparos pesados, reduz a quantidade de manobras para separar os vagões avariados dos em bom estado, reduz o número de vagões retidos e, consequentemente, aumenta a disponibilidade de ativos, melhorando a capacidade de escoamento do corredor. Através do projeto piloto no corredor Centro Leste a VLI conseguiu reduzir em 45% o envio de vagões para oficina, gerando um ganho de 0,44% na DF de vagões graneleiros.

Oct 30, 2017

By Sandra Lúcia de Moraes

O Brasil figura como uma das grandes potências minerais do mundo, sendo esse setor de grande valia para a economia brasileira por gerar milhares de empregos diretos e indiretos. Apesar de sua importância econômica e social, a atividade da mineração ocasiona uma grande geração de rejeitos. O país é detentor de um robusto arcabouço legal, com uma série de regulamentações a respeito do meio ambiente no setor mineral, sendo que 14 delas são específicas para rejeitos da mineração. No entanto, o acidente ocorrido com a barragem da Samarco em 2015 trouxe novamente à pauta a temática dos rejeitos, o que tem instigado uma série de discussões na cadeia da mineração. Neste trabalho, os autores procuraram caracterizar três aspectos: o cenário atual da cadeia produtiva da mineração, a problemática da geração de rejeitos e o nível de desenvolvimento tecnológico que visa o seu aproveitamento. Esse conteúdo está estruturado em duas partes. A primeira parte, retratada neste documento, analisa a cadeia produtiva da mineração e a dinâmica que caracteriza a participação de seus vários atores, assim como as formas de aumentar os investimentos em processos de recuperação de rejeitos.

Oct 30, 2017

By Ricardo Tadeu Meneses Sodré

Laminadores de Tiras a Quente (LTQ) são equipamentos que realizam a transformação de placas de aço em bobinas laminadas de aço. Após a fabricação da bobina é necessário à marcação de todas as bobinas laminadas para possibilitar a identificação e rastreabilidade da bobina. A Arcelormittal Tubarão possui uma máquina de marcar automática robotizada que realiza essa identificação. Ocorrendo falha na máquina de marcar a identificação das bobinas passam a ser realizadas manualmente pelo operador, que não possui a mesma velocidade da marcação robotizada, ou seja, imediatamente ocorre perda de produção e após alguns minutos o gargalo se torna insustentável causando a parada do Laminador de Tiras a Quente. Um estudo minucioso foi desenvolvido através da elaboração de um diagrama de blocos funcionais (DBF), levantamento do histórico de falhas e tempos de manutenção, criação das curvas de confiabilidade e mantenabilidade e dos blocos de confiabilidade (RBD) para realização de simulações. Este estudo permitiu direcionar os esforços para os modos de falhas que mais impactavam na produção, reduzindo significativamente as falhas da máquina de marcar. Para sustentabilidade do resultado os planos de manutenção e inspeção foram revisados utilizando a Manutenção Centrada em Confiabilidade (RCM). O estudo proporcionou um aumento de produção de 15.207 ton/ano.

Aug 7, 2018

By Lucas Tedesco Bolzan

Blindagens contra armas de fogo são de grande importância para proteção do homem, no contexto atual de violência urbana e conflitos armados. Destacam-se os sistemas de blindagem multicamada (SBMs), constituídos por materiais diferentes, pelo seu bom desempenho e menor peso. Um SBM típico é constituído de uma camada cerâmica frontal, uma segunda camada de compósito e uma camada posterior de metal dúctil. Apesar de serem tipicamente fabricados em materiais sintéticos, uma alternativa é a utilização de compósitos reforçados com fibras naturais como segunda camada. Este trabalho tem como objetivo verificar a eficiência de SBMs que utilizam compósitos de poliéster com 30%vol. de fibras ou tecido de sisal. Foram realizados ensaios balísticos com munição 7,62 mm, e verificou-se que os SBMs com fibras e tecido de sisal se enquadram no critério da norma internacional (NIJ 0101.06), de resistir ao impacto balístico e imprimir deformação menor que 44 mm no material de referência (plastilina), além de manterem sua integridade após o impacto.

Aug 17, 2017

By Gerd Weyand

Gontermann-Peipers GmbH (GP) Germany developed a new, high alloyed steel grade for the manufacturing of back-up rolls. The advanced GP double pour casting processes provide highest flexibility in being quite open in rolls work layer chemistry and hence microstructure with no influence on core respectively neck properties. GP took the process advantage to provide a brand new back-up roll grade with remarkably reduced roll wear while operating with textured work rolls. In the meantime several successful trials have been made with this new roll grade on different Skin Pass Mills. As a result the performance of back-up roll and thus availability of mill will be improved while specific costs for mill will drop. This quite new back-up roll grade has recently been launched. As next step increasing the field of applications is under progress.

Aug 17, 2017

By Shibu John

Rising energy demand and steadily decreasing quality of raw materials due to the global resource depletion are great challenges to the steel production today. The FINEX® Process has been developed jointly by POSCO, Korea and PRIMETALS Technologies Austria, to provide the iron making sector with the capability to lower hot metal production costs, environmental pollutions and to increase the flexibility in terms of operation and the choice of raw materials. FINEX® is a new technology combining a gas-based reduction in a series of fluidized bed reactors and a reduction smelting in a melter gasifier. Commenced in April 2007, the first 1.5Mtpa commercial plant has demonstrated the competiveness as an alternative iron making route. Another 2.0 Mtpa, third generation FINEX® (3G) plant was recently installed at POSCO, Pohang Works and has been operating satisfactorily since its blow-in in January 2014. Based on the well-proven plant concept, new process features, the highly competitive production costs and environmental advantages, the FINEX® Process can be considered as a competitive alternative to the conventional blast furnace iron making route.

Aug 17, 2017

By Mario SINNAEVE, Olivier LEMAIRE, Gisèle WALMAG, Sébastien FLAMENT

Many hot rolling mills worldwide face nowadays bonding zone fatigue problems before reaching scrap diameter of the work rolls. This phenomenon is nowadays known to occur in reversing roughing mills both in stainless steel and in carbon steel rolling. The phenomenon can be explained through longer rolling campaigns, inadequate backup or work roll maintenance, harder steel grades or increased throughput by reduced amount of passes to achieve the same thickness. In order to help users in optimizing the roll use, we developed a numerical tool to evaluate and optimize roll maintenance. This paper will review the influence of roll geometries on stresses generated at the roll surface but also at the bonding zone. We will also show how roll geometries can decrease contact fatigue damages by modifying crowning and chamfering procedures, shell thickness, material design or campaign length

Oct 1, 2019

By Maria Vianna Rigatto

Nesse trabalho, foram realizados ensaios de abrasão do tipo roda de borracha em um aço ASTM A242, com o intuito de verificar se a orientação do desgaste em relação à da laminação influencia no comportamento em desgaste do material. Estes ensaios foram executados seguindo a norma ASTM G65-16. Todas as amostras foram fresadas e lixadas para a realização dos ensaios, além de limpas com acetona para medição da massa tanto antes quanto depois do ensaio de desgaste. Utilizando a massa perdida após o ensaio e considerando um possível desgaste da roda de borracha, foi calculado o volume perdido nos ensaios. Além disso, foi medida a microdureza do aço, nos sentidos transversal e longitudinal à laminação, bem como analisadas as microestruturas nos respectivos sentidos antes e depois dos ensaios de desgaste. Os resultados mostraram que a orientação do desgaste em relação à orientação de laminação possui influência na taxa de desgaste e que no sentido transversal à laminação essa taxa foi 9,6% menor que no sentido longitudinal.

Oct 30, 2017

By Gabriel Pessoa Vilas Boas

O presente artigo apresenta um estudo sobre a mistura do nióbio em chapas de alumínio pelo processo Friction Stir Welding (FSW), levando em consideração o efeito de forjamento envolvido na soldagem. O processo FSW, consiste em utilizar uma ferramenta rotativa que em contato com o material a ser soldado gera atrito, provocando aumento de temperatura e deformação plástica. O aquecimento gerado é abaixo do ponto de fusão dos materiais envolvidos, por isso é considerado como solda em estado sólido. Para alcançar os objetivos desta pesquisa, conta-se com a colaboração da Companhia Brasileira de Metalurgia e Mineração (CBMM), que forneceu amostras de Nióbio Metálico em cavaco para proceder aos experimentos deste artigo. A amostra adquirida foi triturada manualmente, em seguida, cominuido em moinho de bola para obtê-lo em forma de pó, viabilizando, assim, a inserção na junta a ser soldada. O nióbio foi colocado entre dois metais de base de Al-Mg 5052F que foi soldado pelo processo FSW, em uma máquina adaptada para esse processo. Após a soldagem foi feito a metalografia na seção transversal onde observou-se uma boa mistura do nióbio no metal soldado. Além disso, foi analisado a microestrutura formada e a composição química através do microscópio eletrônico de varredura (MEV).

Oct 30, 2017

By Mariana Carla Mendes Rodrigues

The present study deals with the effects of strain rate on the functional behavior of NiTi thin wires. The samples, in the austenitic condition at room temperature, were mechanically cycled 20 times by loading up to 6% strain followed by complete unloading, at 25°C. Four different quasi-static strain rates were assessed: 1x10-4, 1x10-3, 1x10-2 and 5x10-2s-1. The functional properties are described by means of critical stress to induce martensite, stress at maximum strain, energy dissipated per cycle and residual strain. The sensitivity of repeated cyclic deformation to strain rate is also analyzed in terms of phase stability. The results show that the fluctuation in the loading plateau, due to non-homogeneous transformation, increases with increasing strain rate. During cycling, it is observed that higher strain rates result in lower critical stress to induce martensite after the 5th cycle. However, the stress at maximum strain is higher at high strain rates, regardless the number of cycles. The accumulation of residual strain also increases with the strain rate due to the higher applied stress. During unloading, both the elastic deformation of stress-induced martensite and the reverse transformation seem to overlap at high strain rates. The dissipated energy behavior changes between the 1st and 20th cycle. No martensite is stabilized after training, but the intensity of the X-ray diffraction peaks of austenite increases with strain rate, as a result of stress relaxation.

Aug 17, 2017

By Christoph Sedivy

Industrie 4.0 is slowly but surely arriving in the melt shops. Furnaces are being equipped with more and more sensors, digital models are increasing the degree of automation, and information is being shared between different aggregates within the plant. Because the electrode control system plays a key role in electric steelmaking, it naturally assumes an important position in the melt shop’s Industrie 4.0 strategy. In addition to reliable, state-of-the-art core regulation functionality, monitoring and reporting tools and the ability to communicate with other equipment are also required. Therefore, the latest generation of our electrode control system, the Melt Expert, was developed based on Industrie 4.0 design principles. Intelligent plant condition diagnostics, performance monitoring, and user-defined reporting are essential modules in this new system. With these functionalities, electrode control systems are developing into the information and control center of the furnace. A newly developed software app brings most relevant process information to mobile devices. This feature allows steelmakers to keep an eye on the performance of their equipment anytime and anywhere. This paper describes the new features of the electrode control system and shares our customers’ operational experience. Our focus is on the practical aspects of plant status monitoring, KPI reporting, and diagnostic functionality as well as the improvements achieved.

Oct 30, 2017

By Franco de Castro Bubani

Cu-base alloys (Cu-Zn-Al, Cu-Al-Be, Cu-Al-Ni), depending on their composition, have martensitic transformations that can be thermally or mechanically induced between a metastable structure called austenite and one or more metastable structures called martensites. In single crystals, depending on the specific composition of the alloy and the crystallographic orientation of the tensile axis, martensite-martensite transformations can be mechanically induced. The hysteresis associated to these martensite-martensite transitions is usually much greater than the one associated to the austenite-martensite transformation. Thus, martensite-martensite transitions are potential candidates for energy dissipation in a mechanical damper. Possible applications that would benefit from high hysteresis include seismic damping devices, dampers for satellites and the aerospace industry, defense and others. We present pseudoelastic cycling results of alloys submitted to different thermal treatments. Our conclusions highlight the fact that, under certain conditions, Cu-base alloys deliver better damping performance than commercially available SMAs and even the new Fe-base SMAs.

Aug 7, 2018

By Ernst Lindemann

Steel suppliers are required to deliver sheets with particular qualities and with lightweight-potential to the automotive industry. New types of steel call for new production processes. SMS group has developed a new micro-mill-concept, the core of which is the belt caster. This was first built on an industrial scale and has been put into operation and developed together with Salzgitter Flachstahl GmbH. The robustness in industrial-scale operation could be verified. The full use of the belt casting technology, mainly related to energy efficiency and CO2 reduction, is realized with the micro-mill-concept. This is an in-line-process, casting and rolling in one line.

Aug 17, 2017

By Frank Schrama

Steelmakers worldwide agree that the most efficient and cost-effective solution in BOF steelmaking is to desulfurize the hot metal between the blast furnace and converter. Various methods are currently in use, among which the Kanbara Reactor (KR, using only lime as a reagent), Magnesium mono-injection (MMI, using only magnesium; also known as the Ukraina-Desmag process) and co-injection (using magnesium and lime/CaC2) are leading. These three hot metal desulfurization methods are compared based on metallurgy, efficiency, costs and overall performance. Both available data from literature and experience from Danieli Corus engineers is used for this study. The KR process is able to reach low sulfur concentrations (> 10 ppm) in hot metal and has lower reagent costs. However, due to higher Fe-loss and heavy wear the KR process has the highest operational costs. The Magnesium mono-injection process is very fast due to the use of the reactive magnesium as reagent. Major problems with resulfurization (sulfur levels below 50 ppm cannot be reached) and the violence of the process made that this process could never get a firm foothold in the western steel industry. The co-injection process with magnesium and lime proves to be able to combine the best of both worlds. It can reach low sulfur concentrations and desulfurize fast. Co-injection is also the most flexible and cost effective.

Aug 16, 2017

By Shibu John

The COREX® process is beside the FINEX® technology the only industrially realized alternative to the blast furnace route for the production of hot metal. Changes in the raw material sector in respect of decrease in quality, strictly enforced environmental laws and positive operation results of COREX® reference plants make it worth to carefully re-evaluate the COREX® technology in comparison with the traditional blast furnace technology. Integrated Plant concepts based on COREX® offer solutions for future challenges of the iron- and steelmaking industry, which include: economical hot metal production; efficient and highly economic export gas utilization (power generation, DRI production, syngas production for chemical products); lower raw material cost, higher raw material availability; environmental friendly high grade steel production. The economic evaluation of different COREX® gas based plant concepts in comparison with the traditional blast furnace route shows that the COREX® technology is highly competitive in the challenging iron and steel producing environment.

Aug 17, 2017

By Jorge Madias

Los hornos eléctricos de arco han sido motivo de una aplicación dinámica de nuevas tecnologías en lo que va de este siglo. La preparación de la chatarra y el uso de materiales de carga alternativos han dado lugar a la concepción de nuevos equipamientos y experiencias en todo el mundo. Surgen nuevos conceptos para el precalentamiento de la chatarra, superando las limitaciones de mantenimiento y ambientales de los conceptos iniciales y mejorando su performance energética. El aporte de energía química para la fusión supera sus límites año a año, requiriendo el desarrollo de equipamiento capaz de una acción rápida y precisa con grandes caudales de gases y sólidos inyectados. Existen nuevas herramientas para eliminar los riesgos de seguridad en la plataforma del horno, haciendo uso de sistemas de enfriamiento más seguros y duraderos, robots, automación de la operación del agujero de colado, y puertas de escoria controladas desde el púlpito.

Aug 17, 2017

By Christoph Aichinger

The optimization and improvement of a modern integral iron and steel works gets more and more difficult as each individual plant is already operated at its best efficiency and at the lowest operational expenditures. However very often the individual plants are considered as stand-alone units and there are losses and inconsistencies on interfaces and take over points, which could be avoided and by that improving the overall performance of the iron and steel works as a holistic unit. Primetals Technologies looked into this subject extensively in the recent years and is now ready to offer new tools and services in order to assist operators to find further potential for improvement in processes, which seem to be fully developed at first sight.

Aug 17, 2017

By Maria Cristina Adami Gatti

Este trabalho tem por objetivo aplicar o conceito teórico e experimental fornecido pela mecânica da fratura dependente do tempo, para avaliar por meio do parâmetro de fratura C* suscetibilidade do aço ASTM A297 Gr HP-Nb, para resistir à propagação de trincas por fluência. Este aço é utilizado na fabricação de colunas de suporte de tubos radiantes de Unidades de Coqueamento Retardado, que operam por longos períodos de tempo em temperaturas elevadas. Os ensaios de fluência convencional e de propagação de trinca por fluência foram realizados na temperatura de 927°C, de acordo com as recomendações das normas ASTM E139-11 e ASTM E1457-13. Dos resultados das curvas de fluência obtida para diferentes valores de tensões aplicadas foram determinadas as constantes, A e n, da relação de Norton. Com os resultados obtidos da taxa de propagação de trinca por fluência, da/dt, em função do parâmetro C*, foi possível ser modelada a equação da/dt = 1,1x10-3(C*)0,78. A morfologia da fratura observada na região de crescimento de trinca por fluência no estado estacionário apresentou modo de propagação interdentrítica, típica de aços com estrutura austenítica bruta de fusão.

Aug 8, 2018

By Aline Lima da Silva

The reduction in SOFC operating temperature due to recent development in materials and fabrication techniques enables the use of ferritic stainless steels as interconnects for SOFCs. Ferritic stainless steels offer many advantages over traditional ceramic interconnects, such as higher thermal and electronic conductivity, as well as relative ease of fabrication. However, the formation of chromium oxide on ferritic stainless steel results in an increase in ohmic resistance and can lead to the loss of cathode catalytic activity (due to Cr volatilization, with cathode poisoning). The oxide growth depends on several factors, such as steel composition, temperature, oxygen partial pressure. In this way, knowing the phase stability, the oxidation behavior of the material and the oxidation kinetics is of great interest. In this context, a thermodynamic study of the oxidation of ferritic stainless steel 430 under oxidizing atmosphere (cathode), at the temperature of 750ºC, is carried out. As one can see, the thermodynamic system can be very complex, involving several phases (chromium oxide, (Fe,Cr,Mn)3O4 Spinel, iron-chromium oxides, etc.). The effect of oxygen partial pressure and alloying elements on phase distribution is evaluated. Thermodynamic modeling is compared with experimental results from literature.

Aug 8, 2018