Search Documents

By Massimilinao Svetina

In 2010 Danieli & C. S.p.A. put into operation a new Pickling Tandem Mill in Cremona (Italy) at Acciaieria Arvedi, the last Pickling line coupled Tandem Cold Mill (PLTCM) in Europe. The plant was tailor-made to suit the specific requirements of this customer; a very broad range of sizes and grades (IF to AHSS as well as DP and TRIP1000) including ultra-thin hot band can be processed, achieving a total capacity of 1.6 Mt/y. The Danieli & C. S.p.A. Turboflo® process was selected because of its proven efficiency and ability to handle ultra-thin gauges at speeds exceeding 400 mpm in the pickling tanks. All the equipment, i.e. pickling section and rolling mills was provided with the last generation of Danieli market-oriented technologies. Danieli & C. S.p.A. - with the support of Arvedi and feedback from the field - is continuously improving its technical design solutions and optimizing plant operations.

Aug 16, 2017

By Roberto Balarini Junior

Tribological behavior of Si3N4 balls sliding against Al2O3 discs in water was investigated by studying the influence of parameters such as initial surface roughness and circular axial run-out of the discs. The objective was to relate these parameters with the occurrence of the phenomenon known as ultra-low friction coefficient (ULFC), which is characterized by µ < 0.01, including the correlation with running-in duration. As a general trend, greater initial surface roughness and circular axial run-out resulted in greater running-in duration. In addition, it was verified that a mixed lubrication regime (hydrodynamic and boundary) is required to guarantee the occurrence of ULFC by comparing the calculated minimum film thickness with the composite roughness of the worn surfaces. Also, ICQ-OES analysis of the water after the tests indicated that a silicon concentration greater than 1.3 mg/l should be fundamental for the occurrence of µ < 0.01.

Jul 31, 2018

By Lucas Sanches Magalhães

A utilização de resíduos industriais é dificultada, na maioria das vezes, pela presença de determinados elementos, como por exemplo, o ferro, justificando assim a sua remoção. Dentro deste contexto, o objetivo deste trabalho foi estudar a sulfatação de um resíduo proveniente da flotação de um minério de ferro e subsequente lixiviação deste resíduo sulfatado. A composição mineralógica da amostra inicial foi obtida por DRX e MEV sendo possível identificar quartzo (SiO2), hematita (Fe2O3) e muscovita (KAl2Si3AlO10(OH,F)2). De acordo com a análise química, os teores dos elementos principais foram: Fe (12,65%), S (4,02%), e Al (0,62%). Na sulfatação, realizada à 250ºC durante 4 horas, foi estudada a influência da relação ácido sulfúrico/amostra (0,1:1; 0,2:1; 0,7:1; 0,8:1; 0,9:1 e 1:1) na extração do ferro. A lixiviação foi conduzida com 5% de sólidos do material sulfatado, sendo avaliada a interferência da temperatura de lixiviação (25°C e 90°C) e do tempo de duração dos ensaios (15min, 30min, 60min, 120min, 180min e 240min). Pelos resultados obtidos observou-se que o tempo de lixiviação foi um parâmetro insignificante. A máxima extração de ferro foi encontrada sulfatando o resíduo na relação ácido/amostra 1:1 e posteriormente realizando a lixiviação deste resíduo sulfatado a 90°C por 30 minutos, alcançando 85,64% de extração do Fe.

Aug 17, 2017

By Johne Jesus Mol Peixoto

A complexidade do formato do molde de beam blank aumenta a importância de se compreender o comportamento do fluxo no interior do mesmo. Neste estudo verificou-se a influência da profundidade de imersão e da velocidade de lingotamento sobre as características de fluxo em um molde de beam blank alimentado por duas válvulas tubulares. Os resultados das simulações matemáticas foram coerentes com os resultados do modelamento físico. A velocidade de espalhamento do jato na região do flange é maior que na alma e este fator pode acarretar na solidificação irregular da pele ao longo da seção transversal. A profundidade de penetração do jato variou entre 66cm e 77cm. A intensidade média de flutuação do menisco foi de 0,22mm, sendo a flutuação máxima encontrada de 0,85mm. Com base nos resultados obtidos, os parâmetros de operação sugeridos são: profundidade de imersão igual a 75mm e velocidade de lingotamento máxima de 1m/min.

Aug 17, 2017

By Nelson SOUTO, Nicolas LEGRAND, Christian COUNHAYE, Don EARLEY

The work is motivated by the automotive customer requirements for a roughness with high peak density (RPc > 75 peaks/cm) on steel sheet surfaces to maintain a good strip surface finish after painting. For that purpose, a new approach is utilized to compute roughness transfer and predict final roughness on uncoated steel sheets (average roughness, skewness, peak density) as a function of temper rolling conditions. The approach is based on the Monte Carlo method combined with the Abott curves and an auto-correlation function to numerically generate roughness profiles for roll and strip respectively. To compute the roughness transfer due to the interaction between roll and strip surfaces during rolling, a composite Abott curve that combines roll and strip Abott curves is used with an asperity crushing model integrated with a rolling model. This enables simulating two roughness transfer mechanisms in the roll bite: the strip asperity crushing mechanism by roll roughness and the strip asperity ploughing mechanism due to roll-strip interfacial sliding speed. The model shows the importance of considering the two mechanisms to predict roughness transfer correctly when strip elongation is high, typically a few percent, and roll bite friction is low. In these conditions, the forward slip at the exit of the roll bite tends to erode strip roughness significantly and decrease considerably the peak density on the strip. For lower elongation levels (~1%) and high roll bite friction, the ploughing mechanism becomes negligible and roughness transfer is controlled by the crushing mechanism only. With these two mechanisms, the model reasonably predicts the evolution of average roughness and peak density over a wide range of temper rolling conditions (new/worn work rolls, hard/soft grades, various elongations), but skewness is more difficult to predict for some trials.

Oct 1, 2019

By Daniel Luiz Rodrigues Júnior

O presente trabalho avalia o efeito da indução máxima sobre a energia dissipada por histerese magnética em amostras de aços elétricos de grão não orientado. Tal relação foi descrita por Steinmetz como uma lei de potência cujo expoente tem valor 1,6. No entanto, esta lei falha quando aplicada a uma ampla faixa de induções magnéticas. Com o objetivo de se avaliar a aplicabilidade dessa equação chapas de aço elétrico foram caracterizadas. Ciclos de histerese foram extraídos com indução máxima variando entre 0,4 e 2,2 T com frequência 5 mHz. A área no interior dos ciclos corresponde à energia dissipada. Estes resultados mostraram uma diminuição do valor do expoente para induções entre 1,2 e 1,6 T. Este fato pode ser explicado pela estagnação do valor do campo coercivo nessa faixa de dados.

Aug 8, 2018

By Roberto Silva de Andrade

O inchamento é um grande problema durante a redução de pelotas de minério de ferro. Várias mudanças podem ser feitas nas pelotas para minimizá-lo. Conforme o sínter utilizado se torna cada vez mais básico, pelotas mais ácidas são desejadas. A adição de MgO, assim como a modificação da basicidade binárias das pelotas pela adição de CaO são soluções que têm sido apontadas. Dessa forma, este trabalho estudou os efeitos do MgO a da modificação da basicidade binária nas seguintes propriedades de pelotas: compressão a frio, porosidade e índice de inchamento. Foram preparadas pelotas com até 5% de MgO e com basicidades entre 0,67 e 1,5. O aumento do teor de MgO causou aumento de porosidade e queda de resistência. A basicidade diminuiu a porosidade e causou aumento de resistência nas pelotas de basicidade 1,0. Tanto o aumento de basicidade quanto a adição de MgO diminuíram o inchamento.

Oct 30, 2017

By João Júnio Pereira Lino

Este trabalho tem como objetivo demonstrar a aplicação das técnicas de laminação termomecânica de aços microligados para obtenção de propriedades mecânicas elevadas em um laminador Steckel. O processamento de um aço com composição química favorável à obtenção de propriedades mecânicas compatíveis com o grau X60 especificado na norma API 5L é demonstrado. Foram alcançados limites de escoamento a 0,5% de deformação e a resistência à tração mínimos de 473MPa e 549MPa respectivamente, alongamento médio de 38%, razão elástica em 86% e temperatura de transição dúctil frágil em torno de -50°C atendendo às especificações da norma.

Aug 17, 2017

By Karl Berger, Michael Steinkogler

The evolution in Metal Cutting: Inventors around the world have been successfully developing innovations for decades, but only some of these developments have had „GAME CHANGING“ potential. One of these innovations is the new developed saw blade LINCUT®, a patented changing system that paves the way for a fundamental reorientation of the entire saw blade industry worldwide through a simple and economical concept for rolling mills or heavy forging lines. Cost efficiency starts with the raw material: Circular saws equipped with a standard saw blade are expected to have a necessary 2 percent standstill per year due to required tool changing. The applied technology reduces this unnecessary loss of production by more than 50%. The ROI can therefore be reached faster which immediately lowers your production costs. No matter what material, conventional carbon steel or highly alloyed stainless steel, the coating and shape of carbide plates is perfected for extended tool life up to 25% with increased performance. Due to LINSINGERs own tool-technology-centre in Austria specialized in research and development of tools, constantly expanding R&D activities, best results are achieved in quality and cost efficiency: a (r)evolution in metal cutting.

Oct 1, 2019

By J. Bas A. F. Smeulders

Traditional laboratory lubrication tests, including those for cold rolling lubricants often involve measurement of neat oils. To achieve increased levels of test severity, such tests are often carried out at high temperatures and prolonged durations. However, we found that the levels of lubricant degradation and wear in these tests can be much higher than in the field. Moreover, steel rolling is not done with neat oils, but with emulsions, where the presence of water influences film formation, surface chemistry and oil composition in the roll bite. To better approach the situation in the field, and thus to be able to develop rolling oils with improved lubrication performance, several lubrication tests were developed for emulsions: direct measurement of film formation and measurement of Stribeck curves, in which the emulsions can be assessed in terms of their boundary lubrication and elastohydrodynamic behaviour. The key innovation is that also another test method was developed, which focuses on boundary lubrication and wear, and the role of extreme pressure and anti-wear additives. Realistic levels of test severity are achieved in the tribometer by mimicking frictional power intensities and flash temperatures for typical cold rolling or tinplate mills. Test conditions can be adapted according to the mill stand or pass number and other cold rolling process parameters. The emulsions are kept at normal operational temperature. Clear differences could be observed between emulsions of various concentration and composition. The viability of the method is illustrated by a number of field cases, in which a good correlation is demonstrated between the laboratory tests and the performance in a pilot or production mill.

Jul 30, 2018

By Emerson de Andrade Monteiro

As ligas de titânio ao Nióbio apresentam grande potencial de desenvolvimento graças a excelentes combinações de propriedades. O tratamento termomecânico a elas conferido é importante para atingir as propriedades desejadas. O presente estudo tem como objetivo avaliar o efeito da conformação mecânica nas propriedades da liga Ti42Nb forjada a frio com 80% de encruamento e seguido de envelhecimento. Foram realizados ensaios de tração, medidas de dureza, metalografia e microscopia das superfícies de fratura. Foi possível observar que a liga Ti42Nb apresentou maior dureza e consequentemente maior resistência após o envelhecimento.

Aug 16, 2017

By Francisco Morganti

In order to support hot rolling mill managers in improving the utilization of their plants, SMS group offers well defined Performance Modules. These are technologies, components, automation solutions or services, which can be implemented in existing plants to increase competitiveness in categories of efficiency, productivity, quality and process and product control referred to as “Industry 4.0”. Except the Performance Modules dedicated to the last category, targeting overall process controls, Performance Modules are characterized by quantifiable benefits. Performance Modules related to hot rolling mills are e.g. camber free rolling, modular laminar strip cooling system, new edge masking and intelligent components.

Oct 30, 2017

By D. F. Rodríguez-Pérez, J. Salinas-Reyes, Luis R. Salazar-Garza, C. A. Gómez-De-La-Garza

The Pickling Line Tandem Cold Mill (PLTCM) from Ternium Pesquería started in 2013. It is a line with 5 stands, 6 high; focused mainly on the exposed automotive market, with a wide spread of products with high quality requirements. In addition the operational continuity is very important, for this, one of the greatest challenges is to ensure operational discipline, the order of production, the quality of the input (hot band), operational interruptions, equipment failure, breakage of strip in the mill, among others. In relation to this, it has a strong impact on productivity, customer compliance, damage to equipment, rolls, safety, quality, reprocessing among others. Here is present the results obtained in the project "decrease of strip breaks" which focused on several fronts, discipline in the order of production, previous review of raw material in surface and dimensional defects with automatic inspection equipment in the hot mill, as well as in PLTCM, generation of logic in the redundant systems of alerts and prevention to avoid or minimize strip breaks that were high impact in the past. All these multidisciplinary actions led as a whole to a significant improvement in the performance indicators of the PLTCM, in productivity, compliance, reprocessing and quality in the cold rolled mill.

Oct 1, 2019

By Marcos Paulo Kohler Caldas

A combinação do elevado volume gerado de resíduos de equipamentos eletroeletrônicos (REEE) com o aumento da obsolescência programada faz com que haja a necessidade de se pensar em alternativas para a disposição destes resíduos sem impacto ao meio ambiente e à saúde humana, como a reciclagem com posterior recuperação de metais. Para isso, é necessário conhecer a natureza dos materiais constituintes do resíduo. A Placa de Circuito Impresso (PCI) é um importante representante dos REEE, pois está presente em grande parte dos equipamentos eletrônicos, como nos computadores. Sua composição heterogênea possui um alto teor de metais, alguns deles preciosos, que representam quase a totalidade do valor intrínseco da placa, justificando a importância da reciclagem para recuperação dos mesmos. No presente trabalho foi realizada a caracterização de uma placa de memória de computadores obsoletos para a posterior recuperação dos metais preciosos nela contidos na forma de nanopartículas. Conclui-se que a placa de memória possui 18,9% de metais, 48,4% de cerâmicas e 32,7% de polímeros em massa. Dentre os metais o Cu é o que aparece de forma mais expressiva, constituindo 13,83% em massa da placa. Os metais preciosos Ag e Au constituem 0,053% e 0,069% em massa, respectivamente, porém seu alto valor de mercado justifica a viabilidade de sua recuperação.

Oct 30, 2017

By Mühlböck Marlene

Increasingly stringent global environmental regulations are forcing steel producers to continually improve the efficiency of sinter waste gas treatment. With the Selective Waste Gas Recirculation (SWGR) system from Primetals Technologies, lower production costs can be achieved and the size of downstream waste gas cleaning units can be reduced for investment savings. SWGR features the extraction and reuse of hot sinter off gas from selected wind boxes along the sinter strand, which contributes to improved energy efficiency and off gas treatment in the sintering process. With the next generation of SWGR, Primetals Technologies can provide an energy optimized, emission optimized and environmentally friendly solution that meet customer requirements and country specific regulations. This paper demonstrates the latest developments in selective waste gas recirculation, especially results from pot grate tests and comparison from lab to real plant data. Furthermore theoretical finding and mathematical modelling is presented.

Aug 16, 2017

By Diego José Inforzato

Hot tensile data were correlated with creep data, in Aluminum Alloy AL7475-T7351, as part of a broader research program, aiming at the validation of a methodology that proposes an equivalence between the two kind of results, for metallic materials in general. The methodology is based on a criterion that establishes correlation among the following parameters from each test: the strain rate, ultimate tensile stress, and time to reach the ultimate tensile stress, in tensile tests, are equivalent respectively to the: minimum strain rate, applied stress and rupture time, in creep tests, for a given test temperature. The present material was tested at 3 temperatures: 133,166 and 193ºC, using 3 nominal tensile strain rates in the hot tensile tests: 3.2x10-6, 1.6x10-4 and 6.4x10-3 s-1 and 9 applied stress levels in the creep tests, varying from 140 to 400 MPa. The conversion of the hot tensile data to creep-like data allowed performing the analysis of all the results together according to the traditional creep relations proposed by different authors, namely: Norton, Arrhenius, Zener-Hollomon and Monkman-Grant, with the determination of the corresponding parameters in each case. The equivalence between hot tensile and creep data is also confirmed for this aluminum alloy.

Aug 8, 2018

By Dr. Steven G. Jansto

The market demand for reduced fuel consumption and CO2 emissions in the automotive, energy and construction sectors have further increased the demand for new and advanced higher quality microalloyed grades produced via TMCP. The technological integration of the process and physical metallurgical advancements of value-added niobium (Nb) microalloyed thermo-mechanical controlled process (TMCP) steels continue to be developed and is an important element for these more demanding end user requirements and cost-effective steel production. The reheat furnace process step has a profound effect on the TMCP performance, final hot rolled steel quality and mechanical property consistency during the production of hot rolled steels. The uniformity of heating applied across the entire width, thickness and length of the slab or billet is essential in the successful achievement of consistent customer properties regardless of the chemistry. The resultant ferrite grain size in the final hot rolled product is significantly governed by the initial prior austenite grain size. However, the transition from laboratory melted and TMCP hot rolled heats to the production scale is often quite challenging. Aberrations in the reheating process step at the industrial furnace are often the root cause of mechanical property quality issues. These combustion process metallurgy parameters connect directly to the resultant TMCP product quality and is defined as Combustion Metallurgy

Oct 1, 2019

By Leonardo Martins da Silva

O minério de ferro quando encontrado contendo teores do elemento fósforo acima de 0,05% é considerado rejeito dada sua inutilização para o processamento de fabricação do aço. Tal fato ocorre devido a elevação da dureza do aço tornando-o quebradiço e com fratura. Sendo assim o presente trabalho tem como objetivo a avaliação do efeito do processo de lixiviação ácida como finalidade de redução do teor de fósforo no minério de ferro. Através da utilização do software Termocalc® foi possível analisar as diferentes estruturas formadas em diferentes teores do elemento fósforo. Através da técnica de microscopia eletrônica de varredura (MEV) foi possível analisar a estrutura do minério de ferro após seu tratamento com a energia de micro-ondas. Por meio da técnica de planejamento estatístico fatorial com pontos centrais e axiais foi possível determinar as condições ótimas de remoção de fósforo através da técnica de lixiviação ácida.

Aug 1, 2018

By Ron Webber

With the difficult economic challenges currently facing the steel industry, it is essential to perform a complete analysis when determining which rolls to purchase. A properly designed “Total Cost of Ownership” model can result in significant savings. This paper will review the costs associated with rolls in both Hot Strip and Cold Strip Mills. The multitude of factors that must be considered in performing a complete analysis for the roll purchasing process will be discussed. Models for both Hot Strip and Cold Mills will be presented. Examples where traditional analysis can lead to expensive, incorrect decisions will be presented.

Oct 30, 2017

By Alessandro Martinis

The performance requirements for modern steelmaking facilities are ever more stringent, as customers and markets are continuously pushing for technologies which allow having high quality steel produced in an economic and sustainable way. In the details, this paper has the aim to present the excellent results obtained by integrated steel plant where an EAF is fed with high quality hot ENERGIRON DRI. The recent technology developments, combined with the affirmed basic process design, contributed to further maximize the energy of the DRI, reaching the EAF at temperatures above 600°C with a carbon content up to 3.5%, as confirmed by plant data. These improved input material characteristics resulted in reduced electrical energy consumption and increased liquid steel production.

Aug 16, 2017