Search Documents

By Michel Rodrigo Luiz, Glaudistoni da Silva Félix, Osmar Duarte Junior

This article deals with a project to reduce the preparation time and threading the coils in the input section of a pickling line coupled to the cold strip mill (PLTCM) at ArcelorMittal Vega. The project developed serves for the detection and elimination of bottlenecks in the input section. The project was conceived by the philosophy of the Theory of Constraints (TOC) and Lean Six Sigma (6 sigma), here seen as sequencing serial / parallel in the preparation and threading the coils. In this context, a proposal to modify the automatic sequencing and reduction of interruptions due to failure of the automation / equipment confirmed its effectiveness reducing the total time preparation time and threading the coils in the entry section by 15%. This project was developed without investment costs, bringing gains on the order of US$613,769.00.

Oct 1, 2019

By Leonardo Araújo Peruch, José Fagundes, Henrique Carneiro Pinto, Marco Túlio Costa, Nayara Coutinho, José Fabiano Martins Assunção

The objective of this project was to increase the hot charge by reducing reheating energy consumption and raising the productivity of ArceloMittal Tubarão's hot strip mill by changing the HSM’s schedule process with optimization of the relocation process of slabs after HSM’s chance with focus on slab temperature in reheating time. The project began with the revision of metallurgical rules for the relocation of materials, definition of criteria temperature setting (hot / cold), definition of restrictions of the process and review of modus operandi scheduling process. With the implementation of the process / system it is expected to achieve a 10% increase in the hot charge index in slabs reheating furnaces and increase productivity of the ArcelorMittal Tubarão hot strip mill

Oct 3, 2019

By Rogério Martins Pereira, Charles Pierri de Souza, Lucas Gabriel Correa

The Tandem Cold Mill is composed by stands with rolls positioned so that the rolling force can be transmitted to the strip being processed. Due to the mechanical stresses inherent in the process, the roll bearings are heated and are equipped with lubrication and cooling systems. Nevertheless, there is the challenge of continuously monitoring the temperature of the bearings, which would allow preventive intervention in case of overheating. This paper presents an in-house solution to temperature measuring system applied to the backup roll bearings of a continuous Tandem Cold Mill. The system uses Zigbee technology and is integrated with the main control system, allowing early diagnosis of bearing heating and proper intervention. Results and features of the system are discussed.

Oct 1, 2019

By Jônatas Venancio Barbosa, Dagoberto Brandão Santos, Túlio Magno Füzessy de Melo

In this work, the mechanical and metallurgical behavior of titanium added ultra-low carbon (ULC-Ti) steel under hot and warm working conditions was studied by means of dilatometer compression tests. Double compression schedules were performed at temperatures between 700°C and 1000°C, inter-pass times of 0.5-100 s, and deformations of 0.5 and 0.3 in the first and second stages, respectively, with strain rate of 1 s-1. The analysis of the flow curves obtained allowed the evaluation of the softening characteristics of the steel. The softening and microstructure features indicate different restoration mechanisms depending on the temperature range. Static recrystallization with rapid microstructure restoration is observed at temperatures within the austenitic and intercritical field. Strain induced boundary motion and recovery mechanisms apparently control the restoration process in the ferrite region. In general, flow stress curves showed dynamic recovery behavior. Only the deformation in the intercritical region produced a peak in the flow stress curves. Isothermal holding tests associated with single hit compression indicated the presence of dynamic strain induced transformation, accelerating the softening kinetics at the intercritical region.

Oct 1, 2019

By Samuel F. Rodrigues, Clodualdo Aranas Jr., Fulvio Siciliano

The application of thermo-mechanical control processing (TMCP) in hot rolling of steels has become a common routine since the last 60 years. The understanding of the physical metallurgy behind TMCP played a major role in the early developments. Physical and numerical simulation works are performed firstly to derive the fundamental metallurgical knowledge and secondly to conceive existing TMCP practices. In this paper, a summary TMCP techniques is presented. The occurrence of dynamic transformation of ferrite in the austenite region is shown by means of synchrotron light diffraction methods. This phase transformation mechanism is taken into consideration and its effects on TMCP are proposed in an exploratory way.

Oct 1, 2019

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 Roman Vaynshteyn

In places where Blast Furnaces are usually located, climatic factors may be unfavorable. Raw materials may be exposed to e.g. rain during transport/storage, bringing moisture into the process with consequences for stability and hot metal cost. This paper describes a technology for drying and pre-heating pellets and coke in the stockhouse. It does not require additional handling or logistical equipment and does not introduce extra transfer steps and degradation. Not only can moisture content be reduced, it can be controlled to a stable level by the operator.

Aug 16, 2017

By Jovanir Francisqueto, José Fagundes, Nayara Neves Coutinho, Marco Túlio Costa

The purpose of this project is to increase the visibility of which will be daily produced on the hot strip mill (HSM). The forecast was performed through the implementation of an automated tool for weekly HSM production planning. The project was started with the definition of the weekly planning process, through the determination of the main business objectives, like as: priorities of service (customers and delivery date), definition of HSM’s rules and restrictions of operating resources. Using a sophisticated mathematical model, through the computational simulation is possible the experimentation of various production scenarios, allowing the visualization of volumes by type of sequence, clients / priorities, mix to be produced, cylinder change quantity forecast, better forecasting of the productivity of the HSM, consumption of utilities, within others. Main benefits: sequencing which production orders should be produced, reducing unforeseen stops due lack of material, improving the quality of the stock which allows the reduction of the aging of slabs in the slabyard and the vision of customer services. Computational simulation as a weekly planning tool achieve, with other benefits, to present alternatives for better decision making.

Oct 6, 2019

By Álvaro Lúcio

This paper outlines the DPC process as na economic and environment friendly option for the use of cultivated forest as a source of raw material for metallurgical charcoal.The DPC process was specially developed to bring logistic, environmental, technical, economic and global energy efficiency when compared to termal1 the existing biomass carbonization process. The DPC process utilizes the volatile materials (condensable and non condensable) as a source of the energy required by the carbonization process guarantying its complete combustion. As result the DPC process avoids the burning of termal1 the loaded wood, obtaining a higher charcoal to biomass yield, and avoids the emission to the atmosphere of polluting gases. Gases emitted by the carbonizing wood have na energy termal1e enough to dry the wood soon after its harvesting. By avoiding the storage in the field during na average of 150 days, the resulting economy is quite significant. As a termal1e1 the higher charcoal to biomass yield na termal1e1e economy is obtained through the reduction of the cultivated forest term. This paper emphasizes the economic advantages of the DPC process.

Aug 16, 2017

By Sara Hornby

After almost half a century of experience in using DRI/HBI in electric arc furnaces (EAFs), and taking into account the decrease of natural gas cost in the USA, it is interesting to revisit some trends and controversial issues around this alternative iron source. This paper reviews aspects like the evolution of iron ore quality and its influence on EAF operation; DRI stockpiling and transport, regarding the risk for selfcombustion; optimum charge design; cold DRI/HBI charging (fifth hole, bucket, transporter); hot charging (ways and results); carbon content, metallization and silica in DRI/HBI, and its influence on EAF operation and performance; oxygen / carbon balance; chemical energy and DRI/HBI charge.

Aug 16, 2017

By Henara Lillian Costa

This paper aims to investigate the effects of a possible incorporation of ethanol to the lubricant during engine use on friction and lubricant film thickness, by adding small amounts of ethanol to Group I base (with and without an organic friction modifier) and to formulated oils. Film thickness was measured using ultrathin film interferometry. Friction tests were carried out using a mini-traction machine to obtain Stribeck curves. The film thickness measurements showed that in the region of low speeds, where the elastohydrodynamic film is very thin and therefore boundary lubrication may prevail, the addition of ethanol produced some boundary film, which was not present for the base oils. For the base oil with an organic friction modifier, the presence of ethanol increased the thickness of the low friction boundary film. For the formulated oil, the addition of ethanol reduced film thickness in all lubrication regimes. The friction tests showed some friction reduction due to addition of ethanol to the base oil, in particular at low speeds. For the formulated oil, the addition of ethanol reduced friction at high speeds, which was associated to a reduction in the viscosity of the lubricant, but at low speeds, the presence of ethanol reduced the formation of a boundary layer, increasing friction. For the base oil containing an organic friction modifier, the presence of ethanol increased the range of speeds for which low boundary friction occurred.

Jul 31, 2018

By Breno Totti Maia

In these hard days for Brazil steel market, all steel shops want to achieve the same goal, work with: productivity, low costs and high performance. In this scenario the Slagless® technology (which is applied into BOF converter) was important to reach these targets. After use has been reduced the number of times of tip exchange in more than 04 times. Was reduced too, the time to remove lance skulls. Lance keeps clean during all his life with record number of the life 1255 .Blow keep stable due strong measure control at the nozzles and more improvements are planning.

Oct 30, 2017

By Daniel Hajduk

Efficiency of back up rolls depends mostly on two parameters – length of campaign and dressing amount after the campaign. The longer the campaign (in terms of rolled tones) is, the higher the dressing amount. To solve this task properly it is necessary to know the distribution of accumulated damage in the working layer of the roll caused by previous campaigns and by loads (separating force and bending) during present campaign respecting changing conditions of material properties (hardness) through radius of the roll. To find an optimum dressing amount an algorithm has been developed and specialized computer program will be presented, that takes real measured loads during the backup roll campaign, calculates fatigue damage in the roll and suggests relevant dressing amount. This can help to prolong service life of rolls, minimize the risk of spalls and reach maximum efficiency in terms of rolled tones/km per roll.

Jul 30, 2018

By Diego Berti Salvaro

The morphology, dimensions and chemical composition of tribolayers strongly depend on the pressures and temperatures acting on the contact. They are formed by reactions between the surfaces in contact with each other as well as with the atmosphere, lubricants and possible contaminants. In this paper the influence of test time (180, 500, 1000 and 2500 h) into the formation and characteristics of tribolayers in pairs DLC-stainless steel tested under refrigerant gas R134a atmosphere without presence of lubricating oil was analyzed. The characterization was performed using scanning electron microscopy, energy dispersive spectroscopy (SEM-EDS) (morphology and chemical composition) and white light interferometry (dimensions). The tribolayers thicknesses ranged from 100 to 500 nm and they were composed by elements originated from mutual transfers between the tribological pairs as well as oxides, being more pronounced on the stainless steel surface. The results show that the tribolayers are chemically stable (maintained the same composition over time) and the thickness remained stable after a thousand hours of testing.

Jul 31, 2018

By Anna Carolina Cerqueira Neves

Synthetic fibers have been gradually replaced by lignocellulosic fibers. Compared to the synthetic fiber, natural fiber showed economic and environmental advantages presenting interfacial characteristics with polymer matrices that favor the impact energy absorption by the composite structure. However, so far little has been reported about the hemp fiber embedded in polymer matrices, such as tensile properties. This study aims to evaluate the resistance in tensile tests of epoxies composites reinforced with different percentages of hemp fiber. Tensile tests were submitted with percentage of 0%, 10%, 20% and 30% incorporated hemp fiber in epoxy matrix. The tensile strength and deformation substantially increased the relative amount of hemp fibers incorporated into the polymeric matrix.

Aug 16, 2017

By Markus Reifferscheid

Industry 4.0, Digitalization, Internet of Things (IoT) and Cloud Computing are predominant topics in the world economy at the moment. At the ABM week 2017 Dr. Markus Reifferscheid, Head of Research & Development of SMS-group, will talk about the proceeding digitalization in the steel industry with selected examples of SMS-group. He will present advanced concepts and solutions which are currently being developed.

Oct 30, 2017

By Paulo Rodrigues dos Santos Junior, Luciano Passos de Jesus, Vagno Dordenoni Beltrame, Vinicius Antonio Ramos Pin

Faced with an increasingly demanding and selective market, a thorough analysis of each step of the processes is required in order to achieve high levels of performance. In addition to a major factor of importance in the rolling process, due to its high price, the rolls represent one of the main items in the cost of hot coils production. Using the 6 sigma methodology, there were opportunities for improvement in the grinding process, fatigue analysis, improvement in NDT in rolls, as well as means to guarantee operational stability, which allowed the reduction of roll’s consumption and consequently the cost of production.

Oct 11, 2019

By Mery-Cecilia Gómez-Marroquín

O presente trabalho trata da formação da ferrita de zinco a partir da mistura e posterior reação solido-solido entre o óxido de zinco e óxido de ferro - Fe2O3 puros em proporções equimolares. A faixa de temperatura onde teve lugar a formação foi entre 1073 e 1373 K. Testes de redução da ferrita de zinco sintética-ZF e pós de aciaria elétrica–EAFD foram realizadas usando misturas de CO e CO2 que variaram entre 50 e 100% CO. Ambos os testes (formação e redução de ZF e EAFD) foram suportados usando técnicas de caracterização física, química, estrutural e microscópica. No caso da redução, foi observado que tanto a temperatura como a percentagem de CO, foram os fatores que, mais afetaram a redução de ferrita de zinco contida no EAFD. A máxima percentagem de redução foi 85%, para 100% CO, 1373 K e 105 min, e 52%, para 50% CO, 1373 K e 105 min. Por outro lado, atingiu o 100% para 100% CO, 1273K, em 80.75 min, 60%, para 50% CO a 1373 K durante 105 min.

Aug 16, 2017

By Samuel Filgueiras Rodrigues, Clodualdo Aranas Jr., Gedeon Silva Reis, Eden Santos Silva, Fulvio Siciliano

When austenite is deformed above the Ae3 temperature, partial amount of it transforms dynamically into ferrite by a displacive mechanism. After unloading, it retransforms back into the stable austenite by a diffusional process. This influences the rolling load which decreases under isothermal condition or does not increase with decreasing temperature as rapidly as expected under cooling. Plate rolling simulations under isothermal and continuous cooling conditions were carried out on a 0.09 wt.% Nb X-70 steel. Pass strains of 0.2 were employed together with interpass times of 10 s, and 30 s for the cooling conditions and 0.3 with interval of 10 s at 900 °C for the isothermal experiments; strain rate of 1 s-1 was used during the simulations. The mean-flow-stress (MFS`s) behavior of both conditions indicates that dynamic transformation and dynamic recrystallization were taking place during straining. The critical strains for the initiation of dynamic transformation fell around 0.06 while the critical strain for DRX was 0.12. It has been shown that ferrite is formed due to the applied deformation of roughing passes and increases its volume fraction throughout the finishing rolling stage. Under cooling conditions, the ferrite formation is also favored as the temperature approaches the Ae3 line. Such ferrite forms when the driving force for dynamic transformation is higher than the total free energy barrier preventing its formation. This obstacle consists of the free energy difference between austenite and ferrite as well as the lattice dilatation work and shear accommodation work. The addition of Nb retards the retransformation of the ferrite into austenite. Moreover, holding times after rolling increases the amount of austenite available for microstructure control on subsequent stages. The dynamic transformation (DT) mechanism can be used to design improved rolling schedules

Oct 1, 2019

By Mariana Macedo de Oliveira Lima, Pedro Emílio Gazola, Andrei Locatelli

Boron steel is used in the industry due to its great wear and impact resistance. During the hot rolling production of 15B29 steel flat bars it is a recurrent problem that the bars will present warping while on the cooling bed. Control this phenomenon is an opportunity to have better productivity, preventing metallic losses. Through the observation of the macro and microstructure samples produced with different reheating temperatures and cooling rates, it was found the presence of residual stresses and cracks on warped bars macrostructure. The residual stresses appearance suggest that the material cooling is too fast. Billets temperature on the reheating furnace of 1230°C reduced to 1100°C and the production pace slowed down. Bars temperature when arriving the cooling bed was reduced from higher than 670°C to 625°C. The results obtained made it possible to produce the material with better quality, reducing the warping effect at the cooling bed. The major influence on the materials warping was identified as the cooling rate at the cooling bed and the reheating furnace temperature was adjusted to provide a homogeneous temperature along the bars.

Oct 1, 2019