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By Luiz Antônio da Silva

Este trabalho tem como objetivo apresentar os resultados do procedimento de geração de energia elétrica adicional a geração econômica na CTE2 com gás natural, visando a redução de custo no grupo CSN.O estudo foi efetuado através da avaliação dos preços do mercado de curto prazo de energia elétrica e análise do processo de geração da planta, aos quais permitiram diagnosticar as melhores praticas e definir a melhor configuração operacional.Os resultados apresentados foram significativos para as condições de operação, o que representa redução do custo de energia elétrica para o grupo CSN e aumento da segurança operacional da planta da CTE2.

Jul 31, 2018

By Roberto Abreu Alencar

Com o barateamento dos custos de implantação e inovações em estruturas geradoras de energias renováveis, nos dias atuais a demanda de instalação de fontes renováveis de energia tem aumentado exponencialmente. Porém como toda estrutura estas estruturas estão condicionadas a falhas de vários tipos. Neste trabalho apresenta-se uma análise de falha de uma peça, de uma estrutura de sustentação de um aerogerador de pequeno porte voltado a micro geração de energia. Para a condução da análise da falha foram realizados analises microscópicas, fractografias, análises macrograficas e modelagem em elementos finitos. Assim as causas das falhas foram identificadas, como má escolha de materiais e alguns erros no projeto da peça.

Oct 30, 2017

By Amanda Cristina Medeiros da Silva

Este trabalho tem o propósito de avaliar a temperabilidade de um aço SAE 1040 através da utilização do ensaio Jominy e posteriormente promover tratamentos térmicos, gerando nos corpos de prova condições de arrefecimento diferenciadas para avaliar a influência da severidade de têmpera da salmoura e óleo. A curva de ensaio Jominy gerada apresentou um comportamento coerente para um aço com médio teor carbono. Já os tratamentos térmicos que foram realizados posteriormente revelaram que o meio que gera o maior acréscimo nas propriedades mecânicas é o resfriamento em salmoura, haja vista que os corpos de prova submetidos a este resfriamento apresentaram o maior de dureza.

Aug 16, 2017

By Alessandro Marques

Based on a short overview regarding steel defects in the final product, several refractory approaches to maintain or increase steel cleanliness are reviewed in this publication. By applying a ladle to mold approach, one potential to maintain cleanliness is to reduce the probability of air ingress by selection of a suitable slide gate system. Following this path, also the influence of a special configured impact pot is presented to maintain steel quality. Finally, higher productivity as well as cleanliness can be provided by selection of PROIL as a revolutionary product at the casting machine.

Oct 30, 2017

By Ronaldo Câmara Cozza

Iron aluminide alloy; Ball-cratering wear testing; Rolling abrasion; Wear volume; Coefficient of friction

Jul 31, 2018

By Dusan Ilic

Conveyor system wear of belts and transfers attribute to a significant proportion of the maintenance costs and lost productive hours when handling hard abrasive ores at high unit rates typical of the iron ore industry. The recent growth phase has seen a rapid increase in mine and export capacity, with many new and upgraded plants operating at high throughput and utilisation. Subsequently, the industry has progressed to an optimisation phase, seeking to maximise production capacity and reduce maintenance costs with minimal capital spend. To support this, a programme of modifying designs was executed to improve conveyor transfer chute and belt life, which identified a need to challenge the industry practice for specification of designs to improve the functionality of the installed equipment. While acknowledging the importance of selecting the highest wear resistant materials for the intended application, this paper investigates design criteria related to decreasing conveyor transfer and belt wear. Of focus is a shift in the manner in which designs are specified, from specifications primarily governing geometrical constraints, to those meeting technical and functional requirements aimed at producing optimum geometry for a given set of material handling parameters. An assessment of transfer design criteria is presented.

Aug 17, 2017

By Paulo Masiero

Sintered titanium carbide has been extensively used since the early 1980s for demanding wear-resistant applications and, in particular, in environments characterized by high temperature and oxidation. Thanks to its physical characteristics, especially its low density, titanium carbide (TiC) has been successfully applied in the manufacture of cassette guide rollers for hot steel rolling. However, the peculiar characteristics of the sintered Ti carbides make it difficult their redressing and hence this has always represented the limit for a more extensive application. Very often iron based alloys are preferred even if, in general, they are less cost effective just because they are easier to be redressed by turning. The availability of a simple, compact, fully automatic and reasonably priced CNC machine; specialized in the grinding of guide rollers and able to operate accurately and efficiently -both in contour and in plunge- can definitively solve TiC’s redressing problems and render its use even more widespread and attractive.

Oct 30, 2017

By Helênio Resende Silva Júnior

PT. Krakatau-POSCO coke making plant, located in Cilegon, Indonesia, is the results of the know-how and experience of Paul Wurth (PW) in coke making field. The plant has a capacity of 1,321,000 t/y of gross coke achieved by two coke oven batteries with 42 top charging Paul Wurth “Jumbo” ovens each. PW “Jumbo” oven with a useful volume of 78,92 m3 allows decreasing drastically the number of pushing/charging operation per day with a consequent reduction of the diffuse emissions. Gas treatment plant with a capacity of 88000 Nm3/h has been designed in collaboration with DMT GmbH & Co. KG, adopting the latest technologies with specific design know-how. PT. POSCO-Krakatau plant has been successfully commissioned and started-up in October 2013. The present paper will highlight the main technology features applied in PT. Krakatau-POSCO project for both coke oven and gas treatment plants.

Aug 17, 2017

By Michaela Böberl

State of the art sinter coolers are working based on the cross flow cooling principle. Thus, only a part of the thermal energy can be used for heat recovery application. The other part of the cooling air is brought unused to the environment. Furthermore, environmental regulation regarding dust emission and intelligent usage of exergy are getting stronger. Therefore, Primetals Technologies developed sinter coolers based on the counter flow principle. The cooling air passes the sinter bed in counter-flow direction enabling a direct heat transfer from the hot sinter to the air. The exhaust gas temperature can be maximized by using the total heat of the hot sinter. Due to the possible usage of the total exhaust gas amount, diffusive dust emission is reduced to zero. Two types of counter flow coolers are in the portfolio of Primetals Technologies. One type is based on a stationary shaft, in which the hot sinter is charged. The flow of the hot sinter is in vertical direction from top to bottom, in counter direction than the cooling air. The second type is a circular hopper cooler. The hot sinter is charged on top of a moving bed. At the bottom of the bed the sinter is discharged. The cooling air flows also from the bottom to the top, following the counter flow principle. Depending on the requirements, one of the two counter flow cooler types can be chosen for optimized and efficient cooling of hot sinter..

Oct 30, 2017

By Guilherme Corrêa Soares

The effects of temperature and strain rate on the mechanical behavior of a superelastic NiTi wire were investigated by uniaxial tensile testing. A universal testing machine with an attached heating chamber was used for the tensile tests. Temperature influence was studied through straining of samples until rupture at a fixed strain rate and temperatures of 25, 50, 75, 100, 125, 150, 175 and 200 °C. Strain rate effects were investigated by straining samples until rupture at room temperature and strain rates of 10-2, 5 x10-3 , 10-3, 5 x 10-4 and 10-4 s-1. The effects of temperature and strain rate on NiTi mechanical behavior were discussed in terms of critical stress to induce martensite and austenite yield strength, when applicable; upper plateau stress, transformation plateau length and ultimate plateau stress. It was found that increasing test temperature and strain rate shifted the stress-strain curve upwards, albeit temperature displayed a greater influence. Plateau length increased with temperature, but no significant changes were detected as a result of different strain rates.

Aug 17, 2017

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 Renata Cristina Teixeira

The lubricant oil is a complex mixture of different basestocks and additives. Engine oils evolved from the use of pure mineral basestocks back in the early years of automotive industry to the advent of synthetic, fully formulated, low ash lubricants. This evolution was driven by a number of factors, such as new engine designs, extended durability needs, increased fuel economy needs, environmental concerns, feedstock prices and availability and legal issues. This paper uses technology prospecting on literature and patents databases to allow an investigation on the historical evolution of engine oils. Main basestocks (mineral, hydrotreated, polyalphaolefins, esters) and additives (antioxidants, antiwear, friction modifiers, detergents and dispersants) are characterized according to their research effort. Technology prospecting data is crosschecked against the evolution of engine oil classes, allowing an analysis of how the main drivers push the development of lubricant oil quality. A research effort was identified in late 1990’s until mid-2000’s and related to the adoption of chemical limits for lubricants. Different patterns for the articles and patents publication account for the high value technological knowledge has in this industry. Technology prospecting is seen as a useful methodology for the understanding and forecast of lubricant technology movements.

Jul 31, 2018

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 Pedro Cunha Alves, Wagner Viana Bielefeldt, Vinicius Cardoso da Rocha, Julio Aníbal Morales Pereira, Antônio Cezar Faria Vilela

Consideráveis esforços vêm sendo realizados para aumentar o desempenho das operações metalúrgicas e a qualidade do aço produzido. Nesse sentido, o papel das escórias no processamento do aço tem se tornado de muita importância. Com o objetivo da otimização das escórias, numerosos estudos têm sido conduzidos para uma melhor compreensão do efeito da composição química e demais propriedades da escória sobre a viscosidade, bem como, sua influência sobre o controle da limpeza inclusionária. Também se tem observado uma evolução das técnicas experimentais de laboratório que são empregadas para a investigação estrutural e medidas das propriedades físicas das escórias. Essa evolução e investigação são fundamentais, inclusive, para o ambiente prático da indústria do aço.

Oct 1, 2019

By Rafael Pereira Ferreira

O objetivo deste trabalho consiste em caracterizar o comportamento termomecânico do aço inoxidável austenítico AISI 316L a partir dos parâmetros de encruamento (h), recuperação dinâmica (r) e recristalização dinâmica (n, t0,5). Na parte inicial das curvas de escoamento plástico a relação sc/sp = 0,92 é relativamente alta, sendo um indicativo que o amaciamento promovido pela DRV é intenso, corroborado a moderada EFE, ?sfe = 66,86 mJ/m2. Na segunda parte das curvas vê-se que há um atraso na cinética de amaciamento dinâmico com maior valor para t0,5 e menores valores do expoente de Avrami n, devido à competição entre os mecanismos DRV-DRX

Aug 17, 2017

By Larissa Fernandes Nunes

O presente trabalho teve como objetivo caracterizar a temperabilidade de uma liga Fe-Ni-Cr. Amostras do material foram submetidas a temperaturas de encharque de 800ºC e 1100ºC e resfriadas utilizando salmoura e nitrogênio líquido. Para a caracterização do material, foram realizadas análises de EDS, MEV e DRX para se determinar, respectivamente, a composição química das fases, a microestrutura e a transformação de fases que podem ter ocorrido. Os resultados microestruturais não mostraram evidencias de transformação de fase, mas que houve o surgimento de maclas de deformação associadas à ciclagem térmica. No entanto a difração de raios-x para amostras tratadas a 800ºC, com aparentemente segregação intergranular, evidenciou alguma transformação de fase.

Oct 30, 2017

By Elaine Aparecida Santos Carvalho Costa

Esse trabalho tem como objetivo produzir e caracterizar uma rocha artificial composta por chamote e brita e uma resina epoxídica, visando obter um material nacional oferecendo uma alternativa econômica e ecológica. Primeiro foi determinada a composição granulométrica de maior empacotamento dos resíduos, para a produção dos corpos de prova foi utilizado vibração, vácuo e compressão. Os corpos de prova foram submetidos a ensaio físico, ensaio de flexão, desgaste abrasivo e resistência ao ataque químico. As rochas produzidas artificialmente apresentaram propriedades mecânicas dentro da faixa esperada e propriedades físicas abaixo do esperado quando comparada com outras rochas artificiais, se mostrou resistente ao ataque químico e resistente ao desgaste abrasivo, podendo deste modo ser empregadas para piso de alto tráfego.

Oct 30, 2017

By Felipe Fardin Grillo

A cal e a fluorita são os principais componentes das escórias dessulfurantes. Entretanto, a busca por tecnologias consideradas menos poluentes vem tomando espaço neste setor. Dessa maneira, a necessidade de desenvolvimento dos processos faz com que as usinas siderúrgicas busquem melhorias no processo. Neste contexto, este trabalho tem como objetivo realizar um estudo de substituição da cal convencional por resíduo de mármore e também da fluorita por aluminato de cálcio. Os ensaios foram realizados a 1.600°C e as amostras foram retiradas periodicamente durante 25 minutos afim de se avaliar a dessulfuração ocorrida no metal. Os resultados indicam a viabilidade da utilização do resíduo e do aluminato de cálcio em escórias dessulfurantes para aço.

Aug 8, 2018

By Rodrigo Alberto Moreira Gomes

São apresentados os resultados da instalação de uma câmara de combustão compacta para a substituição de óleo combustível por coque de petróleo, em um sistema de secagem e moagem de minério de níquel denominado Usina Sul, instalado na Unidade de Niquelândia – GO, da Votorantim Metais. Esta nova câmara de combustão, desenvolvida em parceria com a Dynamis Engenharia e Comércio, atingiu eficiências de queima acima de 95% (comprovada por medições realizadas em Planta Piloto). Além de elevada eficiência de combustão, esta câmara compacta possibilitou que se atingisse o patamar de 100% de substituição de óleo por coque de petróleo, representando ganhos significativos no custo da Unidade. Ganhos também foram observados na vida do refratário da câmara existente, denominada câmara VMN.

Jul 31, 2018

By Adelson Dias de Sousa

O objetivo deste trabalho é mostrar os estudos para remoção de sulfatos no efluentes industrial da Votorantim Metais Zinco, unidade Três Marias.Um dos maiores desafios na indústria que trabalha com meio sulfúrico em seus processos, é a remoção de sulfato de seus efluentes. Neste sentido a Votorantim avaliou vários processos distintos a fim de atingir uma concentração máxima de 250mg/L de sulfatos, dentre eles, precipitação química, redução biológica e resina de troca iônica.Dentre os processos avaliados, o que apresentou os melhores resultados foi a precipitação química através da formação de etringita, composto de fácil separação sólido-líquido, atingindo resultados de concentração de sulfato inferiores a meta máxima de concentração.

Aug 16, 2017