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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 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 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 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 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 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 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 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 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

By Nicola Santangelo

The current economic crisis and growing environmental issues have led the steel industry to face the simultaneous effects of low demand and production overcapacity in a globalized steel market, whilst confronting high energy prices and the need to comply with the green economy. Heat Recovery from waste gas of the Electric Arc Furnace (EAF) represents one of the greatest opportunities to reduce the consumption of primary energy and reduce the CO2 emissions in steel industry. The heat of the off-gas, if recovered and converted into electrical power, can make the whole Fumes Treatment Plant autonomous from the electric point of view, thus making it a “Zero-Energy FTP”. The concept is to substitute the Cooling Components (Water Cooled Panels and Air Cooler) are substituted with Heat Recovery Components (Hot Water Cooled Panels and Heat Exchanger). The recovered heat can be converted into power by using an Organic Rankine Cycle (ORC) turbine. The heat recovered by the HWCP and the Heat Exchanger is characterized by a variable thermal power, which affects the efficiency of the downstream ORC System. Danieli, in collaboration with the University of Udine, has developed the Thermal Stabilizer Unit (TSU). Danieli has realized the first step towards Zero Energy FTP at ABS steelmaking plant (Italy) by installing a CHR® - Clean Heat Recovery. This plant has been started up on 17th October 2014. The HMI of the CHR® is integrated in the HMI of the furnace, so all the process could be kept under control by the furnace operator. At ABS recovered thermal power reaches 5.5 MW. The max power production reached with CHR plant in ABS (over 1MW of electric power) consents an annual saving of approx. 500,000 EUR.

Aug 16, 2017

By Jan Knobloch

Inter Stand Cooling (ISC) can increase productivity of a HSM and improve final mechanical properties of the strip. Constant Target Exit Temperature can be ensured for the whole strip length eliminating skid marks and other temperature oscillations of the transfer bar. The paper deals with advanced control module of ISC. Essential mathematical models of the control system is introduced and basic functionality is explained. Temperature model is based on FEM. Mechanical and thermal properties of the strip are calculated from chemical composition using neural network. Further on an experimental possibilities for investigation and design of ISC cooling headers will be shown. In conclusion practical experience with ISC on various HSM will be discussed.

Jul 30, 2018

By Stephanie L. Kaster, John G. Speer, Blake M. Whitley

Niobium-microalloying technology has been increasingly applied in a wide range of steel applications over the past half-century, to increase strength, control microstructure, enhance properties and enable a variety of applications. To achieve desired performance levels, thermomechanically processed microalloyed steels are widely supplied by the steel industry for high volume applications in hot-rolled plate, sheet and structural steels. However, in steel long products and forgings, the final properties are often generated by downstream users, after heat-treatment, surface hardening, forging or wire drawing. Two examples are presented highlighting advancements associated with Nb-microalloying, to enhance microstructures and properties developed during thermomechanical and/or downstream processing. In the first example, a 0.02 wt. pct. Nb addition was made to a medium-carbon bar steel intended for induction-hardening applications requiring fatigue and fracture resistance in bending and torsion. The Nb addition as well as thermomechanical bar processing led to beneficial refinement of both the pre-induction and post-induction microstructures. In the second example, a 0.01 wt. pct. Nb addition to a high-carbon wire rod was found to refine the pearlite colony size and interlamellar spacing, and increase the hardness.

Oct 1, 2019

By Marco A. Ramírez-Argáez

A 2D mathematical model was developed for the plasma arc welding process. Computational simulations based on mass and momentum conservation equations as well as Maxwell equations were performed by using the commercial software PHOENICS. The model predicts the electric characteristics of the arc column, flow patterns, temperature contours and electrical potential, by varying the composition of the cover gas, in this case, argon and nitrogen. It was found that an arc of nitrogen with respect to one of argon generates more intense jets, greater voltages, and lower temperatures in the arc column for welding arcs current of 150 A and 10 mm arc length.

Oct 30, 2017

By Tobias Krull

The characterisation of iron ore from a materials handling point of view is paramount in order to provide the best possible design for the desired application and maximise equipment uptime at the lowest possible capital and operational expenditure. Problematic issues in materials handling applications often arise in the iron ore industry due to the high density of the ore as well as the abrasive nature of the product. One of the key issues encountered during the handling of iron ore is excessive wear due to either impact or sliding abrasion. The applications and equipment typically affected by accelerated wear issues are mass flow hoppers, transfer chutes and conveyor belts. These wear issues often result in unplanned down times and loss in production which can lead to a considerable loss in revenue. This paper provides an overview of the best practises in the materials handling characterisation of iron ore and discusses available techniques for the modelling of iron ore in applications where accelerated wear is experienced. The application is illustrated through a number of industry relevant case studies for which engineering design work was undertaken to successfully reduce the wear rates of different materials handling equipment.

Aug 1, 2018

By Adriane Lopes Mougo

Super duplex stainless steel presents a biphasic structure composed by ferrite and austenite with different characteristics and properties. In the micromilling process the cutting edge radius has similar dimensions to the grain size. The biphasic structure found in this material could influence on the cutting tool life and the surface integrity of the workpiece. Due to its low machinability, caused by high hardening level and low thermal conductivity, the process can produce built-up edge and high surface roughness (Ra). In this work it is performed an experimental study of the micromilling of super duplex UNS 32750 and the influence of the cutting speed (Vc) and feed per tooth (fz) on the surface integrity and tool wear. The design of experiments considered two levels and three replicates. Results indicate the increase of roughness for bigger feed per tooth, small influence of the cutting parameters on the burr formation. The tool presented flank wear after the experiments.

Aug 8, 2018

By Edo Engel

Whereas only a handful of decades ago, typical blast furnace working volumes were below 1000 m³, such furnaces are currently designated compact or even mini blast furnaces. For certain business cases, however, small furnace sizes remain an attractive option. Decades ago, this size blast furnace would have produced a maximum of 0.3 Mtpa with its 600 m³ working volume over a campaign of up to four years. The current state of technology and operational know–how will allow a similarly sized furnace to produce over 0.7 Mtpa while achieving the multiple decade campaigns that have become familiar to steel producers in full sized operations. This level of productivity, but especially the reliability and supply security associated with mature technology, allows for integration into minimills or taking a first step towards a full scale BF–BOF integrated mill. Steel producers considering such scenarios, which are typically attractive for emerging economies, are confronted with fundamental decisions, one of which is for the technological basis for the compact or mini blast furnace to be included in the plant. This article addresses some of these decisions from an operations–based perspective. A small number of case studies is included.

Aug 16, 2017

By Stefan Stein, Jorge Davo, Adrian Villanueva, Abhay Kulkarni, Shane Hoff

Pellet sizing plays a key role in the productivity of the entire pelletization and subsequent induration processes, whereas uneven pellet sizing can increase the circulating load of the balling circuit inducing operational instability leading to production loses. The present work focuses in comparing the agglomeration kinetics, expressed as the number of pellets produced in a determined target size range, of different organic binder-bentonite binder systems. The batch experimental results show that the binder system has a great influence in the resulting pellet sizing, which could lead to advantages in terms of balling circuit efficiency and eventually operational de-bottlenecking.

Oct 1, 2019