Component level strategies for exploiting the lifespan of steel in products

Approximately 40% of annual demand for steel worldwide is used to replace products that have failed. With this percentage set to rise, extending the lifespan of steel in products presents a significant opportunity to reduce demand and thus decrease carbon dioxide emissions from steel production. This article presents a new, simplified framework with which to analyse product failure. When applied to the products that dominate steel use, this framework reveals that they are often replaced because a component/sub-assembly becomes degraded, inferior, unsuitable or worthless. In light of this, four products, which are representative of high steel content products in general, are analysed at the component level, determining steel mass and cost profiles over the lifespan of each product. The results show that the majority of the steel components are underexploited - still functioning when the product is discarded; in particular, the potential lifespan of the steel-rich structure is typically much greater than its actual lifespan. Twelve case studies, in which product or component life has been increased, are then presented. The resulting evidence is used to tailor life-extension strategies to each reason for product failure and to identify the economic motivations for implementing these strategies. The results suggest that a product template in which the long-lived structure accounts for a relatively high share of costs while short-lived components can be easily replaced (offering profit to the producer and enhanced utility to owners) encourages product life extension. © 2013 The Author.

The Iron and Steel Industry in Asia: Development and Restructuring

The paper examines the development and restructuring of the iron and steel industry in Asian countries. Studying countries that have integrated steelworks with large blast furnaces (South Korea, Taiwan, China and India) and countries without (Thailand, Indonesia and Malaysia), the paper shows the difference in the development processes across the countries and across time, and points to the diversity of the development experience of these countries. The paper argues that significant differences in steel production technologies in terms of initial investment and minimum-efficient scale, the changing role of the state, and shifting demand structures in the domestic steel markets of each country have been the important factors that led to the differences in the development path of the steel industry in each country.

GEOTECHNICAL AND ENVIRONMENTAL IMPACTS OF STEEL SLAG IN EMBANKMENTS

Steel slag is a byproduct of iron and steel production by the metallurgical industries. Annually, 21 million tons of steel slag is produced in the United States. Most of the slag is landfilled, which represents a significant economic loss and a waste of valuable land space. Steel slag has great potential for the construction of highway embankments; however, its use has been limited due to its high swelling potential and alkalinity. The swelling potential of steel slags may lead to deterioration of the structural stability of highways, and high alkalinity poses an environmental challenge as it affects the leaching behavior of trace metals. This study seeks a methodology that promotes the use of steel slag in highway embankments by minimizing these two main disadvantages. Accelerated swelling tests were conducted to evaluate the swelling behavior of pure steel slag and water treatment residual (WTR) treated steel slag, where WTR is an alum-rich by-product of drinking water treatment plants. Sequential batch tests and column leach tests, as well as two different numerical analyses, UMDSurf and WiscLEACH, were carried out to check the environmental suitability of the methods. Tests were conducted to study the effect of a common borrow fill material that encapsulated the slag in the embankment and the effects of two subgrade soils on the chemical properties of slag leachate. The results indicated that an increase in WTR content in the steel slag-WTR mixtures yields a decrease in pH and most of the leached metal concentrations, except aluminum. The change in the levels of pH, after passing through encapsulation and subgrade, depends on the natural pHs of materials.

Foaming of slags under dynamic conditions

Slag foaming under dynamic conditions has been studied in laboratory scale to examine the influence of properties commonly used to describe the foaminess and foam stability of slags under steady-state conditions. Synthetically produced slags with compositions relevant to tool steel and stainless steel production were studied through X-ray equipment in measurements simulating the dynamic conditions found in real processes. It is found that the dynamic systems display a more complex behavior than systems Under steady state. Traditional theories for foaming do not seem to be valid for slag foaming under dynamic conditions. The foam displays a fluctuating behavior, which the presently available models are not able to take into account. The concept of a foaming index does not seem to be applicable, resulting in the need for alternative models.

Aço em varão para betão armado: caracterização do material e enquadramento atual

Dissertação para obtenção do grau de Mestre em Engenharia Civil

Caracterização laboratorial de misturas betuminosas com incorporação de agregado siderúrgico inerte para construção (ASIC)

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Civil na Área de Especialização de Vias de Comunicação e Transportes

Vivienda obrera en Bilbao y el Bajo Nervión: las casas baratas, una nueva forma de alojamiento (1911-1936)

A finales del siglo XIX y principios del siglo XX la provincia de Vizcaya despuntó en el contexto internacional como importe centro extractor de mineral de hierro y como relevante foco productor siderometalúrgico. Las explotaciones mineras se adueñaron de los Montes de Triano y las fábricas conquistaron las márgenes del Río Nervión, arrastrando tras de sí una densa marea humana. Alojar a esa población se convirtió en una cuestión de primer orden. Paralelamente, las instituciones estatales desbordadas por problemas similares en otros puntos de la geografía española, idearon y pusieron en práctica un complejo engranaje administrativo para erigir las primeras viviendas sociales. Así, las denominadas Casas Baratas fueron la respuesta oficial a la insuficiencia de vivienda obrera y Vizcaya fue una de las provincias donde mayor desarrollo tuvieron este tipo de propuestas constructivas. De este modo, la presente investigación comienza indagando sobre el origen de la problemática en Bilbao y la Cuenca del Bajo Nervión, para después repasar las medidas adoptadas por el Estado y la Diputación de Vizcaya en esta materia. Hecho esto, se da paso a un concienzudo repaso de las características principales de la edificación de Casas Baratas en toda la provincia de Vizcaya, descendiendo, posteriormente, a la realidad de Bilbao, Baracaldo, Sestao, Portugalete, Guecho y Erandio, haciendo hincapié en las inquietudes locales. El estudio finaliza con un ejercicio comparativo con las Casas Baratas de Barcelona, Sabadell y Tarrasa, estableciéndose similitudes y divergencias con el foco industrial más importante del momento en el panorama nacional.

Lot sizing and furnace scheduling in small foundries

A lot sizing and scheduling problem prevalent in small market-driven foundries is studied. There are two related decision levels: (I the furnace scheduling of metal alloy production, and (2) moulding machine planning which specifies the type and size of production lots. A mixed integer programming (MIP) formulation of the problem is proposed, but is impractical to solve in reasonable computing time for non-small instances. As a result, a faster relax-and-fix (RF) approach is developed that can also be used on a rolling horizon basis where only immediate-term schedules are implemented. As well as a MIP method to solve the basic RF approach, three variants of a local search method are also developed and tested using instances based on the literature. Finally, foundry-based tests with a real-order book resulted in a very substantial reduction of delivery delays and finished inventory, better use of capacity, and much faster schedule definition compared to the foundry`s own practice. (c) 2006 Elsevier Ltd. All rights reserved.

Estudo sobre a potencialidade de uso das escórias de aciaria como adição ao concreto

A geração de resíduos tem se mostrado um problema de preocupação mundial crescente. Muitos rejeitos, sejam industriais ou urbanos, muitas vezes acabam por poluir o meio-ambiente, causando problemas de armazenagem de certos materiais. Além disso, materiais alternativos a partir desses rejeitos podem ser mais baratos, apresentando muitas vezes características de desempenho melhores que os materiais convencionais. As siderúrgicas, em nível mundial, vêm enfrentando um problema comum, que consiste no que fazer para que a totalidade da escória gerada no refino do aço em aciarias elétricas ou à oxigênio tenha uma solução de aproveitamento melhor do que vem sendo feito atualmente. Na fabricação do aço as escorias são geradas em duas etapas: a primeira provém do chamado refino oxidante (forno elétrico a arco ou convertedor à oxigênio) e a segunda do refino redutor em processos de metalurgia na panela (forno-panela). Este trabalho tem como objetivo principal o de apontar potencialidades de uso da escória de aciaria elétrica, com destaque para a proveniente do forno-panela (escória do refino redutor), na indústria da construção civil através de testes em que a escória é utilizada, após moagem, como adição ao cimento Portland comum. Inicialmente foram realizados ensaios de viabilização para se testar a pozolanicidade, resistência à compressão, expansibilidade e profundidade de carbonatação de concretos gerados com diversas adições de escórias de aciaria elétrica. Comprovada a sua viabilidade partiu-se para os ensaios complementares do trabalho utilizando-se somente uma escória do refino redutor. Nesta segunda etapa foram realizados ensaios de caracterização de todos materiais estudados, ensaios de expansibilidade, ensaios mecânicos e de durabilidade dos concretos gerados com esta escória e ensaios de microscopia eletrônica de varredura e de difração de raios X do material. Após o estudo realizado comprovou-se ser perfeitamente viável a utilização de até 10% da escória do refino redutor (forno-panela- FP) como adição ao cimento para produção de concretos. Inclusive, independente do tempo de estocagem da escória, pode-se constatar melhorias no concreto produzido.

Diferenciações na produção siderúrgica e implicações para o desenvolvimento na Amazônia Oriental Brasileira

As estratégias de modernização da Amazônia concebidas pelo Estado nacional tinham em sua proposta as fragilizadas diretrizes geopolíticas de segurança e desenvolvimento regional, voltadas centralmente para a instalação de empreendimentos industriais, dentre elas as indústrias siderúrgicas independentes, sob a noção de que desta atividade passaria para a produção produtos de aço e assim se processaria o desenvolvimento regional. Pela análise das diferenciações das rotas de produção independente, integrada e semi-integrada é possível se compreender como os elementos das plantas industriais se comportam em cada rota e como se inter-relacionam com a socioeconomia regional. O trabalho de pesquisa junto à guseiras permitiu identificar que a instalação de siderúrgicas independentes nos municípios de Açailândia (MA) e Marabá (PA) gerou expectativas frustradas de desenvolvimento local, consolidando-se, portanto, apenas como atividade que possibilitou o crescimento econômico, pois manteve uma rota de produção que articulou a atividade com a socioeconomia regional em bases frágeis e insustentáveis, apoiada, sobretudo na demanda de carvão vegetal. As estruturas de custos e elementos estruturais de cada rota permitiram identificar as diferenças que cada rota apresenta, principalmente na relação mantida com a economia regional, por envolver novos processos, tecnologias e produtos diferenciados. A lógica produtiva das siderúrgicas independentes baseadas na transferência e externalização de custos para a sociedade, relações de trabalho limitadas e na degradação ambiental, sem, contudo, estabelecer processos de inovação, conduziu ao não estabelecimento de processos de desenvolvimento de base local. A perspectiva das rotas de produção siderúrgica integrada e semi-integrada que se instalam na Amazônia tem bases para alterar o cenário regionalmente desenhado e transformar as inter-relações mantidas pela siderurgia independente na Amazônia Oriental, pois articulam elementos que contribuem para a consolidação de efeitos de encadeamento para trás e para frente.

Analise das emissões de CO2 e de energia - simulação com novas tecnologias siderúrgicas

The process of steel production emits a large quantity of greenhouse gases, specifically carbon dioxide (CO2), and the reduction of such emissions is one of the main challenges for the industry in the 21st. Century. To quantify these emissions, the Worldsteel Association (association of the 170 large steel manufacturers of the world) published a methodology (CO2 Emission Data Collection) for calculation and comparison of CO2 emissions among its members. After that, in 2010, this methodology became an ISO (International Organization for Standardization) norm. Today, the calculation of the CO2 emissions in steel making companies follow the ISO 14404-1 for units with blast furnaces and the ISO 14404-2 for units with electric furnaces. In the last years, new technologies were and continue to be developed for the steel making sector aiming at energetic improvements and greenhouse gas reductions (mainly CO2) by the several processes involved in the production of steel. This work had the objective of producing a tool to calculate the CO2 emissions for the steel making sector. An Excel spreadsheet was developed to calculate the emission intensities of CO2 of a steel plant, the Usina Presidente Vargas, of the Companhia Siderúrgica Nacional (CSN). The spreadsheet furnishes results of CO2 emissions and energetic fluxes, and simulates the benefits that some of the new technologies can give to the company. The spreadsheet calculates the emissions in two ways: a) based on the carbon fluxes that enter the unit, and b) based on the emissions of each specific process within the unit (coking, sinterization, blast furnace, among others)

Influência da adição do nióbio no comportamento mecânico e microestrutural do aço SAE 6150

Pós-graduação em Engenharia Mecânica - FEG

Análisis del comportamiento a corrosión de armaduras embebidas en probetas de mortero, con sustitución parcial de áridos y cemento por escorias blancas de horno cuchara

El hormigón armado es el material estructural más empleado en construcción, lo que exige un exhaustivo control tanto de los materiales que lo componen como de su ejecución, con el fin de garantizar la vida útil para la que ha sido proyectado. Uno de los principales problemas de la durabilidad del hormigón armado, es la corrosión de sus armaduras. Existen en la actualidad diferentes métodos que intentan detener el proceso de corrosión, entre ellos, los inhibidores superficiales de corrosión. El continuo incremento en la producción de acero desde el siglo XIX, ha producido un desequilibrio entre los productos fabricados en las industrias siderúrgicas y los residuos generados. Como consecuencia, toneladas de residuos son depositados en vertederos, provocando graves daños medioambientales con el paso del tiempo. El volumen de escorias producidas en la industria siderúrgica en España asciende a 2,55Mt al año, de ahí la importancia del reciclaje de estos productos y de su integración como materia prima en el proceso de fabricación de otros materiales. Partiendo de estas premisas, en el presente trabajo de investigación se ha estudiado el comportamiento a corrosión, de barras de acero de armar embebidas en probetas de mortero, en las que se ha sustituido parcialmente el árido y el cemento por escorias blancas de horno cuchara (LFS), mediante técnicas electroquímicas y gravimétricas. Para ello, se han fabricado probetas prismáticas de 6 x 8 x 2 cm3 con diferentes porcentajes de ión cloruro, introducidos en el momento del amasado, tanto en probetas patrón como en probetas con escorias LFS. El análisis de los resultados obtenidos permite concluir que las probetas patrón y las probetas con escorias LFS tienen comportamientos similares en presencia de cloruros por encima del 0,4% en peso de cemento y por tanto que la sustitución de escorias LFS por arena (25%) y cemento (30%) no afecta negativamente a la corrosión de las armaduras. Por tanto, el uso de escorias LFS en el proceso de fabricación de hormigón armado es una práctica que presenta ventajas competitivas respecto a las técnicas de construcción tradicionales, desde el punto de vista económico y medioambiental. En cuanto a los inhibidores superficiales de corrosión, no han resultado eficaces en probetas con escorias LFS, independientemente del porcentaje de ión cloruro, mientras que en probetas patrón han sido eficaces para porcentajes de ión cloruro igual o inferior al 0,8% en peso de cemento. ABSTRACT Reinforced concrete is the most widely used structural material. This implies that rigorous control must be applied in order to guarantee the life-span and performance of structures made using this composite material. One of the main problems regarding concrete durability is bar corrosion. At present, there are different methods adopted to stop the corrosion process, among them, surface corrosion inhibitors. The continuous growth in steel production since the 19th century has led to an imbalance between waste products generated in steel production processes and their subsequent use. As a consequence, mass dumping at waste disposal sites has been causing a significant environmental problem over the years. The amount of slag produced by the steel industry each year in Spain amounts to 2.55Mt, hence the importance of recycling by-products from steel production so they can be used as primary material in the manufacturing process of other materials. Starting from this working hypothesis, and using electrochemical and gravimetric techniques, this research work aims to analyse and study the corrosion behaviour of steel rebars embedded in mortar specimens, containing ladle furnace slag in partial substitution for aggregate and cement. Prisms were manufactured from 6 x 8 x 2 cm3 with different percentages of chloride ion introduced at the time of mixing, in standard specimens and specimens with LFS slag. Results from the analysis show that the standard specimens and those containing LFS slag display a similar behaviour in the presence of chlorides. Furthermore, when LFS slag is replaced by sand (25%) and cement (30%) corrosion of rebars is not negatively affected. Additionally, the use of LFS slag in the manufacture of reinforced structures is a practice that represents a competitive advantage over traditional construction techniques, from both an economic and environmental point of view Finally, as for surface corrosion inhibitors, they have not proved effective in specimens containing LFS slag, regardless of the percentage of the chloride ion, whereas in standard specimens they have been effective in chloride ion percentages not exceeding 0.8% (as to the cement amount).

Utilização de resíduo de mármore e de óxido de boro em escórias sintéticas dessulfurantes para aços.

O mercado atual exige das indústrias siderúrgicas aços de melhor qualidade produzidos por meio de processos que causem menor impacto ao meio ambiente. Dessa forma, este trabalho teve como objetivo reciclar o resíduo de mármore gerado na indústria de rochas ornamentais, que possui em sua composição óxido de cálcio (CaO) e óxido de magnésio (MgO). O CaO é suficiente para substituir a cal nas escórias e o MgO contribui para a diminuição do desgaste dos refratários, através do emprego do resíduo no processo produtivo do aço. Além disso, foi realizada a substituição da fluorita por óxido de boro como fluxante na composição de misturas dessulfurantes. O resíduo de mármore foi caracterizado utilizando as seguintes técnicas: análise química via EDXFR, análise granulométrica via espalhamento de luz, área de superfície específica pelo método BET, difração de raios-X, microscopia eletrônica de varredura (MEV) e análise de micro-regiões por EDS. Visando verificar a eficiência na dessulfuração, foram formuladas misturas sintéticas utilizando a cal convencional ou resíduo de mármore, e a fluorita ou o óxido de boro. As misturas foram formuladas com o auxílio dos programas de termodinâmica computacional, Thermo-Calc e FactSage. Estas misturas foram adicionadas no aço fundido a temperatura de 1600°C sob atmosfera de argônio e agitadas por meio de um rotor de alumina. Amostras de metal foram retiradas para verificar a variação do teor de enxofre durante o experimento. O resíduo de mármore caracterizado, apresentou em sua composição 40% de CaO e 14% de MgO, na forma dos carbonatos CaCO3 e MgCO3. Obteve uma perda de massa de 42,1%, na forma de CO2 a temperatura de 780°C. Os experimentos mostraram que, as misturas testadas apresentaram, na maioria dos casos, eficiência de dessulfuração acima de 60%.

Introduction: improving manufacturing performance through technology diffusion, implementation and management

The role of technology management in achieving improved manufacturing performance has been receiving increased attention as enterprises are becoming more exposed to competition from around the world. In the modern market for manufactured goods the demand is now for more product variety, better quality, shorter delivery and greater flexibility, while the financial and environmental cost of resources has become an urgent concern to manufacturing managers. This issue of the International Journal of Technology Management addresses the question of how the diffusion, implementation and management of technology can improve the performance of manufacturing industries. The authors come from a large number of different countries and their contributions cover a wide range of topics within this general theme. Some papers are conceptual, others report on research carried out in a range of different industries including steel production, iron founding, electronics, robotics, machinery, precision engineering, metal working and motor manufacture. In some cases they describe situations in specific countries. Several are based on presentations made at the UK Operations Management Association's Sixth International Conference held at Aston University at which the conference theme was 'Achieving Competitive Edge: Getting Ahead Through Technology and People'. The first two papers deal with questions of advanced manufacturing technology implementation and management. Firstly Beatty describes a three year longitudinal field study carried out in ten Canadian manufacturing companies using CADICAM and CIM systems. Her findings relate to speed of implementation, choice of system type, the role of individuals in implementation, organization and job design. This is followed by a paper by Bessant in which he argues that a more a strategic approach should be taken towards the management of technology in the 1990s and beyond. Also considered in this paper are the capabilities necessary in order to deploy advanced manufacturing technology as a strategic resource and the way such capabilities might be developed within the firm. These two papers, which deal largely with the implementation of hardware, are supplemented by Samson and Sohal's contribution in which they argue that a much wider perspective should be adopted based on a new approach to manufacturing strategy formulation. Technology transfer is the topic of the following two papers. Pohlen again takes the case of advanced manufacturing technology and reports on his research which considers the factors contributing to successful realisation of AMT transfer. The paper by Lee then provides a more detailed account of technology transfer in the foundry industry. Using a case study based on a firm which has implemented a number of transferred innovations a model is illustrated in which the 'performance gap' can be identified and closed. The diffusion of technology is addressed in the next two papers. In the first of these, by Lowe and Sim, the managerial technologies of 'Just in Time' and 'Manufacturing Resource Planning' (or MRP 11) are examined. A study is described from which a number of factors are found to influence the adoption process including, rate of diffusion and size. Dahlin then considers the case of a specific item of hardware technology, the industrial robot. Her paper reviews the history of robot diffusion since the early 1960s and then tries to predict how the industry will develop in the future. The following two papers deal with the future of manufacturing in a more general sense. The future implementation of advanced manufacturing technology is the subject explored by de Haan and Peters who describe the results of their Dutch Delphi forecasting study conducted among a panel of experts including scientists, consultants, users and suppliers of AMT. Busby and Fan then consider a type of organisational model, 'the extended manufacturing enterprise', which would represent a distinct alternative pure market-led and command structures by exploiting the shared knowledge of suppliers and customers. The three country-based papers consider some strategic issues relating manufacturing technology. In a paper based on investigations conducted in China He, Liff and Steward report their findings from strategy analyses carried out in the steel and watch industries with a view to assessing technology needs and organizational change requirements. This is followed by Tang and Nam's paper which examines the case of machinery industry in Korea and its emerging importance as a key sector in the Korean economy. In his paper which focuses on Venezuela, Ernst then considers the particular problem of how this country can address the problem of falling oil revenues. He sees manufacturing as being an important contributor to Venezuela's future economy and proposes a means whereby government and private enterprise can co-operate in development of the manufacturing sector. The last six papers all deal with specific topics relating to the management manufacturing. Firstly Youssef looks at the question of manufacturing flexibility, introducing and testing a conceptual model that relates computer based technologies flexibility. Dangerfield's paper which follows is based on research conducted in the steel industry. He considers the question of scale and proposes a modelling approach determining the plant configuration necessary to meet market demand. Engstrom presents the results of a detailed investigation into the need for reorganising material flow where group assembly of products has been adopted. Sherwood, Guerrier and Dale then report the findings of a study into the effectiveness of Quality Circle implementation. Stillwagon and Burns, consider how manufacturing competitiveness can be improved individual firms by describing how the application of 'human performance engineering' can be used to motivate individual performance as well as to integrate organizational goals. Finally Sohal, Lewis and Samson describe, using a case study example, how just-in-time control can be applied within the context of computer numerically controlled flexible machining lines. The papers in this issue of the International Journal of Technology Management cover a wide range of topics relating to the general question of improving manufacturing performance through the dissemination, implementation and management of technology. Although they differ markedly in content and approach, they have the collective aim addressing the concepts, principles and practices which provide a better understanding the technology of manufacturing and assist in achieving and maintaining a competitive edge.