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By Juliano Braz Possatti, Arnaldo Carneiro Salles, Cleudson dos Santos Rego, Leandro de Lucas Mendes

The increase in customer demand for steels with higher surface requirements, associated with the need to increase ArcelorMittal Tubarão's HSM productivity, it was necessary the development of controls and actions to reduce scale losses within the scenario of high productivity. This article describes the path followed by the hot strip mill team in order to reduce the occurrence and severity of scales.

Oct 10, 2019

By Tiago Seixas Bittencourt

Technological developments, associated with the constant worry about the environmental impacts arising from industrial activity, it has driven the development of technologies and practices for efficient fumes and particulates capture arising from the manufacturing processes of steel in steel plants in general. Currently, the electric steelshops in operation with Electric Arc Furnaces (EAF), seek parameterize/design dedusting systems able to retain most of the particulates generated during melting and refining of steel in FEA through configurations of equipment, technologies and parameters operation in order to equalize the antagonistic relationship between effective fumes capture and energy balance of the EAF. The present work gets as a fundamental premise to evaluate critically the possible different settings of the usual dust removal systems, as well as their respective classical parameterizations. The work main purpose is to establish a general rule evaluation technique for dedusting system considering the different modes of operation of an Electric Arc Furnace.

Jul 30, 2018

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 John Anthony Vasquez

During the last years Riva Acciaio Verona has taken the decision to invest in the route of a fully automated meltshop. The aim is to reduce at the minimum the operator's intervention from the bucket preparation till the ladle transfer to the continuous casting bay. The foundation for achieving the goal is the introduction of innovative technological solutions (fully automated cranes for bucket charge in the EAF, robots for sampling, etc. The paper underlines how the different solutions are based on the best practices to improve operator's safety and describes the different steps of the project, the different solutions adopted and the results in terms of production, energy savings, cost reduction and improved safety. Details are presented for: scrap yard management and bucket preparation, EAFs centralized controls and related robots for auxiliary operations (sampling, EBT cleaning, scraper for slag door automation, complete mass & energy balance based on process control), LFs centralized controls and process integration.

Aug 16, 2017

By Maycon de Almeida Gomes

Fiber reinforced polymeric composites have received widespread attention in the past four decades because of their high specific strength and modulus. In particular, research works have disclosed the potential advantages associated with the use of lignocellulosic fibers as the reinforcing phase in polymer composites (2-3). Among various natural fibers, pineapple leaf fibers exhibit excellent mechanical properties. The main chemical constituents of pineapple fibers are cellulose (70–82%), lignin (5- 12%) and ash (1.1%). The superior mechanical properties of pineapple leaf fibers are associated with their high cellulose content (6). This work aims to make the analysis of the Izod impact energy against volume fraction of palf fibers of epoxy composites reinforced with PALF. The fibers were incorporated into the epoxy matrix with volume fraction from 0 to 30%. After fracture the specimens were macro photograph analyzed.

Aug 16, 2017

By André de Cabral Oliveira

With the onset of the global economic crisis in 2008, and more precisely from 2009, production routes in iron making as blast furnace, sinter and coke oven, indicated a significant increase in frequency as well as intensity of undesirable incidents. The cost impact of such deteriorations of the production chain cause significant losses ranging up to several hundred million dollars annually. On the other hand, opportunities for processes improvement are contributing to enhance process efficiency and results, and also reduce or even avoid losses from unexpected incidents. The use of specialized services for processes has gained projection along the plants and emerged as an attractive alternative to increase results by increasing the performance and reducing costs and expenses. Process Services are formatted to achieve cooperative and customized solution during planned or urgent interventions, conducting feasibility studies, process improvement, training, among others, providing knowledge, information and crucial actions to preserve and optimize processes and plant facilities.

Aug 2, 2018

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 Rodrigo Fina Ferreira

This paper presents a mineral liberation study on two iron ore samples from the Quadrilátero Ferrífero, in Brazil: compact itabirite of low-grade metamorphism (CI) and friable itabirite of high-grade metamorphism (FI). The quartz liberation spectrum for both samples have been obtained through QEMSCAN analyses, carried out for several comminution degrees, to compare the liberation characteristics and to evaluate the evolution of the quartz’s liberation degree after fragmentation. The results have shown significant differences in liberation spectrum between the itabirite samples studied. The liberation process of FI was easier than of CI, due its high porosity and larger crystal size compared with CI, which has shown more complex mineral assemblages with low porosity and smaller crystals. The quartz liberation spectrum has shown that grinding at P95 of 0.210 mm for the FI sample, and of 0.045 mm for CI sample, should result in satisfactory liberation for subsequent concentration step.

Aug 1, 2018

By Xihuai Gong, Hongshuang Di, Jianping Li, Ning Yan

In this work, we investigated the effect of the rolling process (warm-rolled or cold-rolled) on microstructure evolution and mechanical properties of 9Mn steel. After intercritical annealing at 670°C for 10min, both cold-rolled and warm-rolled microstructures are composed of ultra-fined austenite and intercritical ferrite. The austenite in warm-rolled sample includes two types of morphology, namely equiaxed and lamellar, which exhibits a wide distribution of grain-size. The incomplete recrystallization or recovery behavior of ferrite in warm-rolled and annealed sample results in higher yield strength and shorter yield point elongation. Moreover, the warm-rolled and annealed sample extends the TRIP-related work hardening over a broad strain range, resulting in a better combination of ultimate tensile strength and total elongation.

Oct 1, 2019

By Kelen Juliane Mucelin

In order to better understand the tribological behavior of self-lubricating materials, Fe-Si-C matrix composites containing solid lubricants added during the mixing step were studied. The samples were produced by conventional powder metallurgy route, presenting total contents of 5%, 7.5% and 10% in volume of h-BN and graphite mixtures as solid lubricants. The composites were evaluated in terms of tribological properties, under reciprocating sliding conditions, and mechanical properties by using tensile tests. Additionally, the wear scars were characterized by Raman spectroscopy and scanning electronic microscopy. Higher total contents of solid lubricants greatly increased scuffing resistance however decreased mechanical properties. Furthermore, increasing h-BN contents reduces both properties. These results confirmed the applicability of such sintered composites as self-lubricating parts, reaching values up to 7000 N.m for scuffing resistance combined with ultimate tensile strength of 220 MPa.

Jul 31, 2018

By Javier Martinez Rubio

In this paper we will discuss the benefits of a very innovative way of introducing MgO in the blast furnace operation through the sinter, using mini lumps of dunite. By changing the traditional way of using an MgO bearing material in fines form (particle smaller than 5 mm), most of the MgO inserted material behaves as inert during the sintering process, with the effect of having the following parameters (among others) improved: productivity at the sintering bed, permeability inside the blast furnace, energy consumption, stability of the operation.

Aug 16, 2017

By Enrique Francisco Somolinos Garcia-Morales

In this paper we will discuss the benefits of a very innovative way of introducing MgO in the blast furnace operation through the sinter, using mini lumps of dunite. By changing the traditional way of using an MgO bearing material in fines form (particle smaller than 5 mm), most of the MgO inserted material behaves as inert during the sintering process, with the effect of having the following parameters (among others) improved: productivity at the sintering bed, permeability inside the blast furnace, energy consumption, stability of the operation.

Aug 1, 2018

By André Carlos Silva

Dewatering stage is among the most important industrial unit operations, and is wide adopted in many different industries, due the fact that a large portion of industrial products is produced using suspensions of solids in liquids. Nowadays the mineral processing tailings disposal is a big problem due the environmental degradation produced. The phosphate rock processing in Anglo American Phosphate Brazil, situated in Catalão/Go/Brazil, generates around 180 t/h of tailings for a plant feed of 480 t/h (approximately 37,5% of the processing plant feed), with 5 to 10% of solids and approximately 14% of P2O5. Nowadays the tailings are sent direct to the tailings dam. The present work proposes the paste production using with the tailings from phosphate rock processing plant divide in two different stages. The first one composed by the free settling of the material in presence of industrial flocculants in a graduated cylinder with 2.0 L of internal volume for one hour, in the same way it must occur in conventional thickeners. After that time, the clarified liquid was drained and the remaining pulp was sent to the second stage consisting in the tailings vacuum filtration. Ten different flocculants and nine different filter media were tested. The found results were satisfactory for paste tailings production with solids percentage around 65%.

Aug 8, 2018

By Antonio Adel dos Santos, Carmos Antonio Gandra, Fabricio Mazola da Silva Paiva, Vicente Tadeu Lopes Buono

Abstract Usiminas Steel Plant in Ipatinga installed an accelerated cooling device named CLC (Continuous On-Line Control) in 2010, enabling it to supply steels produced by TMCP (Thermo Mechanical Control Process) technology. This technology complements the TMCR (Thermo Mechanical Control Rolling), with the inclusion of the accelerated cooling process after controlled rolling. There are various gains in terms of quality and productivity associated to the application of such technology. However, the flatness control for API steel becomes crucial because large thermal stresses may be generated due to thermal heterogeneity during the fast cooling when the austenite phase decomposes mostly into ferrite and bainite. In literature, there is lack of knowledge regarding a full understanding of the relation among cooling conditions and plate flatness. Therefore, this work has focused on the effect of the cooling strategy for API steels, aiming at optimizing flatness and keeping the mechanical properties within the specified ranges. The starting point was dilatometer simulation, where cooling conditions such as start cooling temperature, SCT, finish rolling temperature, FRT, and cooling rate, CR, were changed in order to evaluate their effect on microstructure. Those laboratory conditions supposed to give the best results were transposed to industrial scale, so as to produce experimental lots of plates with five different cooling strategies. It was shown the possibility to find a cooling profile that guarantees the balance between mechanical properties and flatness requirements. The influence of cooling strategy on flatness was explained by the varied heat transfer regimes occurring from hot steel surface to the ambient

Oct 1, 2019

By Wenting Zhu, Liqing Chen, Junjun Cui, Zhenye Chen

In this presentation, a low carbon high strength steel microalloyed with Nb and Ti was processed by thermo-mechanical controlled process (TMCP) containing two stages of controlled rolling. The austenite with various grain sizes was obtained by austenitizing this hot-rolled steel at different temperatures. And the effect of austenite grain size on bainitic transformation was investigated in a dilatometer to reveal microstructural change. The results showed that the microstructure of the hot-rolled steel was mainly composed of granular bainite, lath-like bainite, and martenite/austenite constituents (M-A constituents). With increasing the austenitizing temperature, or increasing the austenite grain size, the microstructure was changed from granular bainite to lath bainite. When the steel was reheated to a lower temperature of 860 ºC, a relatively higher start temperature (Bs) was measured for bainitic transformation. This was mainly caused by the formation of solute-depleted region in the austenite and the promotion of the granular bainitic nucleation. The highest reaction rate occurred at austenitizing temperature of 1000 ºC with fine grain size, while the coarse austenite grain can lead to a sharp increase in the amount of bainite. An analysis was made on the kinetics of bainite transformation which was controlled by the volume diffusion of C atom.

Oct 1, 2019

By Evan Thomas

It has been shown before that liquids can slip at a solid boundary, which prompted the idea that parallel-surface bearings can be obtained by the use of alternating slip and non-slip regions in the direction of fluid flow. The amount of slip at the wall depends upon the surface tension at the liquid - solid interface, which in turn depends on the chemical composition of the surface and its roughness. In the present study a heterogeneous surface was created by coating half of a circular glass disc with a coating repellent to glycerol. A rotating glass disc was placed at a known distance above the coated stationary surface and the gap was filled with glycerol. With the top surface moving in the direction of slip to non-slip region, a pressure build up can be theoretically predicted. The pressure gradient in the two regions is constant, similar to that in a Rayleigh step bearing, with the maximum pressure at the boundary. In order to accurately measure the force generated by the pressure increase, a load cell was attached to the heterogeneous disc. Experiments were conducted by varying both sliding speed and distance, and the resultant load carrying capacity was measured and compared with theoretical calculations. This allowed the slip coefficient of the coated surface to be evaluated.

Jul 31, 2018

By Esteban Ruisanchez Rodriguez

In this paper we will discuss the process of the grain size customization of the EBT filler sand in relationship to the technical characteristics of the furnace and its tap hole. By customizing the grain size distribution, the glassy area formed on the top of the tap hole varies and supports differently the metallurgical pressure of the molten steel providing increased free opening speeds. Taylor made sand improves therefore the free opening rate, reduces the tap to tap time and increases the lifespan of the tap

Aug 16, 2017

By Osvaldo Guilherme Comineli

While the hot cracking of Cu-containing steels is a serious and widely known problem for the industry, the literature reports that copper only slightly impairs the hot-ductility measured in laboratory. A distinction is drawn between hot ductility and hot shortness and the respective cracking operating mechanism involved at the respective range of temperature. The representability of the laboratory assessment of hot cracking of Cu-containing steels by hot tensile tests compared with actual results in industrial practice is discussed. The effectiveness of the variable affecting in each cracking mechanism and respective temperature range, focused in improving the hot cracking assessment of Cu-steels and the relative importance of oxidation will also be discussed. It is concluded that the hot tensile test in argon might be a good simulation if properly interpreted and that the role of oxidation is secondary in causing hot shortness. A schematic diagram for the hot tensile test is proposed.

Oct 30, 2017

By Hongshuang Di, Tianyu Zhang, Huiqiang Huang

A CMnSiAl transformation induced plasticity (TRIP) steel was used to study the effect of retained austenite on room-temperature mechanical properties. The steel plates with retained austenite were obtained by hot rolling, cold rolling and subsequent continuous annealing. The starting and finishing temperature of hot rolling are between Ac1 and Ac3. Reduction ratio of cold rolling is 75%. The continuous annealing is carried out at different intercritical temperatures. The relationship between work hardening exponent and retained austenite was discussed. The results show that, the Ac1 and Ac3 were much high because of the alloy elements, and the temperature range between them was wide. Due to the high hot rolling temperature, the grains was hereditarily refined as a result of dynamic recrystallization. Annealing at intercritical temperature of 930 ºC, retained austenite with relatively high stability reached a maximum volume fraction of 25%, a maximum total elongation of 30.2% and a best ultimate tensile strength × total elongation of 20.1 GPa·%. Instantaneous work hardening exponent reflects strengthening mechanisms at different strain stages. The TRIP effect of retained austenite is the main mechanism during deformation. With retained austenite of sufficient amount and high stability, continuous work hardening was observed in the tensile specimen of 930 ºC.

Oct 1, 2019

By William Sergio Flores Roman

Los aceros para armaduras de hormigón tienen que exhibir una buena relación entre resistencia y tenacidad que se ve reflejado en la performance del producto en servicio al ser aplicado a esfuerzos exigidos. Acerbrag es una empresa que produce aceros para la industria de la construcción teniendo en su gama los aceros de medio carbono para la fabricación de barras conformadas de dureza natural para armaduras en estructuras de hormigón. El objetivo de este trabajo es encontrar criterios de ventanas de trabajos operacionales y de control para la manufactura de aceros con buenas propiedades mecánicas en términos de resistencia y tenacidad. Este paper muestra los resultados de los trabajos realizados en las diferentes áreas productivas para conseguir un producto final con mayor resistencia a altas exigencias en servicio, además, reporta diferentes aspectos del proceso de manufactura del producto que van desde el ajuste de la composición química del acero, incluyendo criterios de propiedades mecánicas objetivos, criterios de calidad interna mostrando la microestructura de la barra antes y después de los cambios y finalmente la calidad dimensional y superficial de la barra nervurada, este último potenciando la falla prematura del material. Todos estos cambios, se ven reflejados finalmente en la performance de la barra, sometida a los nuevos criterios de exigencia en los ensayos mecánicos.

Oct 30, 2017