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By Guilherme Corrêa Soares

Deeper understanding about the strain hardening behavior of steels has become necessary due to its importance in industrial processes such as mechanical cold forming, rolling and drawing. In this work, the strain hardening behavior of AISI 304, non-grain oriented electrical (NGO) and dual phase steels was investigated. Tensile tests were performed and the strain hardening behavior of each steel was studied by the Hollomon’s equation. X-ray diffraction measurements and hardness tests were also carried out in order to characterize the specimens. Different work hardening stages were observed in each steel during the deformation process. The results obtained are discussed in terms of the relationship among the instantaneous strain hardening coefficient, hardness and eventual phase transformations. The instantaneous strain hardening coefficient of dual phase and NGO increases after the yield point, rapidly reaching its maximum and then steadily decreases until tensile strength is reached. In AISI 304’s case, the strain hardening coefficient keeps raising to high values in response to a large strain and then rapidly decreases before reaching the tensile strength. In comparison to the other steels, AISI 304 shows higher instantaneous strain hardening coefficient value, which persists even in large strains. This is a consequence of its strain hardening mechanism based on stress-induced martensite transformation.

Aug 16, 2017

By Valeria Romina Stricker

Acerbrag es una empresa Argentina siderúrgica de 50 años de trayectoria, desde el año 2007 pertenece al grupo Votorantim de origen Brasilero. Se dedica a la elaboración de aceros largos para la construcción. La planta industrial cuenta con un proceso de acería integrado, horno eléctrico, horno cuchara y máquina de colada continua. La materia prima es 100% chatarra, característica que la diferencia del resto de las acerías del país. Debido a esto el enfoque principal de este proyecto es reducir el costo de fabricación mediante un “empobrecimiento” de la carga metálica a partir de la flexibilización de los límites de especificación. Esto implica un mayor control del desempeño de los procesos a fin de detectar posibles desvíos, para ello fue necesario implementar la utilización de herramientas estadísticas y gráficas para su monitoreo. La modificación en el mix de fabricación no muestra una alteración significativa en la composición química y propiedades mecánicas de los productos terminados, situación favorable para la continuidad del proyecto. Se observa además, de la reducción de costo esperada, una ventaja en la operación del patio de chatarra y el proceso de acería y en la utilización de chatarras con altos niveles de residuales tales como Cr – Ni.

Aug 16, 2017

By Mario Andres Albuja Ribadeneira

El presente trabajo pretende encontrar la ruta para incrementar la productividad y reducir el costo de transformación en una acería eléctrica, mediante el uso de la tecnología disponible en el mercado. El método para alcanzar los resultados se enfocan en una drástica reducción de los tiempos de transformador conectado (power-on), los tiempos de transformador apagado (power-off) asi como la reducción en los consumos de las materias primas e insumos para la fabricación de acero por la ruta del horno eléctrico. La experiencia de Adelca arroja resultados que sobrepasan el 100% de productividad y 30% de reducción en el costo de transformación de la palanquilla. Los resultados obtenidos sin duda alguna servirán de una guía probada para quienes buscan un mejor desempeño en el negocio del acero.

Aug 16, 2017

By Davide Onesti

Electrode regulation is the technology at the heart of the AC and DC Electric Arc Furnace. As such, in the last decade it underwent continuous improvement to maximize the EAF performances, in terms of process efficiency, machine utilization and operator safety. Given this background, Danieli Automation’s efforts in the field of electrode regulation have been focused on fast response to scrap cave-in, compensation of supply variations, automatic resonance detection, transformer protection, dynamic regulation of the electrical and chemical set-points, coordination and control of slagging and foaming agents, arc irradiance supervision. An extensive analysis of operator utilization and feedback was also carried out to develop an innovative system HMI. In this field, the choice of the variables shown to the user is the key aspect to allow a prompt process evaluation by the operator, who can refer to a condensed set of useful data. This paper will describe the innovative features and embedded models of the electrode regulation module (Q-REG+) and the supervision HMI, together with the effects of their application on EAF process efficiency and system usability.

Oct 30, 2017

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

By Josef Maierl

For the production of advanced high strength steel grades (AHSS) like API X80/X100, dual-phase, martensitic and complex-phase grades a number of hot strip mills need to extend their limits in terms of power and flexibility. Especially for cooling and coiling of these new materials, Primetals Technologies developed the “Power Cooling” and “Power Coiling” technologies. Power Cooling combines the advantages of conventional laminar cooling or “low pressure cooling” with the newly developed “high pressure cooling” with highest cooling rates for flexible operation. The Power Coiler which is needed to coil those high strength grades especially at thicker gauges ensures reliable strip-coiling for a most economical production. To enhance the reliable production of high-strength steel grades for a wide range of strip dimensions, the automation system with its advanced models is an integral part to the mechanical design. In this context the paper presents examples for the installation of power cooling and power coiling in new and modernized HSM.

Aug 16, 2017

By Peter Grawenhof

Universal joint shafts and slipper spindles are commonly used in rolling mills to compensate the design- and process-related offset between the motors and work rolls. Although both types of shafts exhibit on the same kinematic principle, there are basic differences regarding the design concepts. These differences become noticeable on many levels and may become very distinct in terms of Life-Cycle-Costs (LCC). In this respect, a critical comparison between universal joint shafts and slipper spindles can be made.

Aug 16, 2017

By Sihai Jiao, Xiaoming Xia, Bo Yan

Checkered plate, which is also known as floor plate, has a raised pattern that provides excellent skid resistance for a wide range of applications, such as flooring, walkways, platforms, stair treads, covers, etc. As one of most common products, carbon steel checkered plate is used in low strength with a large thickness margin for corrosion and costs a lot in corrosion resistance treatment and maintenance. Although austenitic stainless steel checkered plate meets the requirements of general corrosion resistance, it is also hard to provide a highly comprehensive performance for its low yield strength, which mean higher thickness, higher weight, lower stability of structure. Combined the advantages of stainless steel and carbon structural steel, a roll-bonded clad checkered plate with high performance in skid resistance, high strength and corrosion resistant is developed. The metallography shows metallurgically bonded interfaces. Both external and internal bending at room temperature can be done successfully done without any cracks. The yield strength is also significantly improved. Therefore, roll-bonded clad checkered plate is superior in microstructure, strength, ductility and workability. An application case on a pulverized coal injection platform in an iron-making plant, is also introduced to show the way of processing and installation. After two years of installation on the platform, the product still keeps the original appearance. It implies that the developed plate could keep the facilities functions with much less or no maintenance and make them much safer.

Oct 1, 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 Danilo Gonçalves de Oliveira, Rogério Martins Pereira

Chatter is a widely studied vibration phenomenon that affects most cold mills around the world and its impact on these lines are tremendous: from productivity and quality losses to mechanical equipment damage. The investigation of its origins and how to minimize the occurrences and their impact on the equipment require special instrumentation and algorithms in order to have a detection of the vibrations as soon as they start. This paper presents three methods of identification of chatter on a Tandem Cold Mill and the actions to leave the vibration frequency range before its amplitude achieve catastrophic values.

Oct 1, 2019

By Ulrich Sommers

The Intelligent Furnace (I-Furnace) by SMS group is a smart furnace process and production optimization model. The combination of various tools leads to an optimized heat treatment and production process. It combines a mathematical/physical model to control the furnace with EMG’s IMPOC system for online strength measurement and a newly developed annealing microstructure model to predict material properties. This paper reports about the revamping of an existing galvanizing line, where a mathematical/physical control model has been implemented in combination with an online quality measurement system. This way, the process improvement of continuous galvanizing lines and the quality management of a range of steels including AHSS will be demonstrated. Furthermore, it gives information about the development of the annealing microstructure model to predict material characteristics. Eventually, the I-Furnace will be presented according to the current development and reference status.

Oct 30, 2017

By Lidong Teng

ArcSaveTM is a new generation of electromagnetic stirrer (EMS) from ABB for electric arc furnace (EAF) operation. Its goal is to improve the safety, increase the productivity and reduce costs. Electromagnetic stirring in the melt bath during arc furnace operation will affect the scrap smelting, bath temperature distribution, refining reactions, and also the tapping practice. This paper has summarized the investigation results obtained from the first ArcSaveTM system installed in a 90 ton EBT arc furnace in USA. The hot test results show that ArcSaveTM has enhanced the heat and mass transfer in the arc furnace process. This results in a faster scrap melting rate, lower slag superheat during arcing, more homogenous melt bath, higher decarburization rate and higher EBT free opening frequency. ArcSaveTM has also reduced the tapping temperature and tapping oxygen in the steel. This brings a higher scrap yield and saves ferroalloy consumption in the downstream ladle furnace operation. The lower energy consumption, short tap-to-tap time, and consistent furnace operation bring increased productivity and safety.

Aug 16, 2017

By Giulio Rodrigues Altoé

Environmentally correct composites, made from natural fibers, are among the most investigated and applied today. In this paper, we investigate the mechanical behavior of epoxy matrix composites reinforced with continuous fique fiber, through bending tensile tests. Specimens containing 0, 10, 20 and 30% in volume of fique fiber were aligned along the entire length of a mold to create plates of these composites, those plates were cut following the ASTM standard to obtained bending tests specimens. The test was conducted in a Instron Machine and the fractured specimens were analyzed by SEM, the results showed the increase in the materials tensile properties with the increase of fiber amount.

Aug 16, 2017

By Dagoberto Brandão Santos, Marcus Vinícius Pereira Arruda, Fernando de Souza Costa, Túlio Magno Fuzessy de Melo

The development of advanced high strength steels (AHSS) is motivated by the automotive industry demands for higher strength steels with better formability and stretch-flangeability to avoid fractures during parts forming. In response to this, the new steel grades must have special microstructures in terms of constitution, morphology, distribution and hardness, which are strongly dependent on the chemical composition of the steel sheet and its processing, especially in the continuous annealing stage, in the case of cold rolled sheets. In this study the influence of the annealing heating rate and intercritical temperature (IT) on the microstructural evolution and the final hole expansion ratio of a cold rolled 980 MPa AHSS grade was evaluated. The annealing process was simulated using a Dilatometer and a Gleeble machine, and the microstructures were characterized using scanning electron microscopy, electron backscattered diffraction (EBSD) and nanohardness measurements. The increase of heating rate resulted in an overlap between ferrite recrystallization and austenite formation, changing the austenite morphology from a random to a fibrous distribution, while a higher IT resulted in more homogeneous microstructures and higher hole expansion ratios. This microestructural homogeneity, confirmed by nanohardness measurements, suggested that the difference in hardness between ferrite and the second phase affects the micro-void formation and crack propagation during the hole expansion test.

Oct 1, 2019

By Aperam South America

Balanço Energético Global e Utilidades - 2013

Jul 31, 2018

By Jorge Madias

Durante la laminación de barras y alambrones para construcción civil; perfiles y ángulos estructurales y barras redondas y hexagonales de aceros de corte libre puede presentarse la apertura de la punta o la cola y el estallido central, con la consiguiente parada y caída de la productividad, y pérdida de rendimiento metálico. En este trabajo se analizan las diversas causas que confluyen para que este problema ocurra. Se analiza la influencia de posibles defectos en las palanquillas, las características del corte de las mismas y otros problemas de calidad. Se revisa el rol del precalentamiento previo a la laminación, la refrigeración de los cilindros, el diseño de pasadas y la respuesta del material en función de su ductilidad. Se presentan diversos casos industriales para ilustrar las diferentes razones detrás del problema de la apertura de punta.

Jul 30, 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 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 Jerin Russell

This paper presents a new instrument for real-time detection of excessively coarse material in the overflow pipes of individual hydrocyclones using a non-invasive acoustic measurement technique. The hydrocyclone is an important device used in mineral processing beneficiation circuits for classification of mineral slurries by particle size. It separates a single input stream into two output streams; an underflow of coarse particles that undergo additional grinding for further size reduction, and an overflow stream of finer particles that typically goes directly into a flotation circuit for recovery of the desired mineral. However the hydrocyclone is a major piece of equipment in the beneficiation process that has no instrumentation for directly measuring its performance. The parameters currently measured – inlet pressure, feed flow rate, feed flow density – are common to the entire hydrocyclone cluster which typically has three to twelve hydrocyclones. Thus no information is available to detect individual hydrocyclones that are operating poorly. The system described in this paper detects the presence of unwanted excessively coarse material in the overflow stream of a hydrocyclone using sensors mounted to the exterior pipe surface. It provides real-time monitoring, trending and alarming of the coarse material level. This enables operators to identify poorly performing hydrocyclones, and enables corrective action to reduce or eliminate the coarse material discharge. Improving the classification efficiency of individual hydrocyclones will improve the overall classification efficiency of a hydrocyclone cluster. This leads to less variation in the particle size distribution and slurry density in the flotation feed, which will in turn improve overall mineral recovery. The reduction of unwanted coarse material in the flotation feed reduces the accumulation of that material in flotation cells. This can lead to equipment damage, and unplanned shutdowns due to events such as blocked dart valves.

Aug 16, 2017

By Boryong Lee, Heedong Sung, Minho Park, Sunyoung Choi

Recently, the demand for ultra-thin steel plate with high hardness and strength has been increasing in various industries. In order to satisfy this requirement, steel company designs the chemistry with low CEQ and obtains the required characteristics through quenching and tempering process. Especially, these steels are accompanied by low temperature tempering as a necessary process. Unlike ordinary high temperature tempering steels, it is impossible to improve the flatness after low temperature tempering. Therefore, shape control in the quenching process is very important for securing the excellent quality flatness. In order to obtain flatness in the quenching process, uniform cooling inside the plate should be accompanied. However, the quenching process has limitations in estimating the temperature behavior during cooling because the plate temperature is lowered to room temperature. In this study, a thermocouple was installed inside the actual quenching plate to measure the temperature behavior during cooling and to establish the manufacturing conditions of the quenching plate to ensure excellent flatness quality.

Oct 1, 2019