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By Maycon Athayde

Samarco produces high quality iron ore pellets processed in straight grate furnaces. This process is essential in order to obtain adequate mechanical strength to the pellet transportation and operation in the reduction reactors. All mechanical properties of the agglomerates are obtained during the stage of firing where the slag and sintering bond happens, thus it is a decisive step to improve the pellet quality. Therefore, the velocity distribution of gas flow within this zone must have homogeneous and even velocity distribution. Hence, it was developed a mathematical CFD model to characterize the gas flow in the burning zone, applying the equations of conservation of momentum, mass and energy and an uneven flow distribution was identified and the gas velocity analyzed and validated through experimental data. On the other hand, on the present paper, an improved firing zone burner were developed and industrially implemented in a way to mitigate the uneven flow pattern detected aided by CFD. Different burner designs, based on CFD analysis, were experimented in order to succeed on the aggressive condition. The combustion was investigated and burner efficiency evaluated and compared with the simulation purposed.

Aug 2, 2018

By Oliver Schulz

This paper presents the latest references of the Siemens VAI slab casting technology. Following the connect & cast philosophy Siemens VAI has developed technological packages suitable for installation in existing casters of any original supplier, as well as for complete new machines. A major demand on new machines is to adapt quickly to different market demands. This requirement for flexibility can be divided into two actual trends. Firstly into casting a broad range of steel grades, thicknesses and width on the same machine and secondly having installed slab, bloom and billet caster in one steel plant to deliver all different types of needs on the market. Depending on the condition of the existing machine the focus of modernization ranges from the substitution of single components featuring state-ofthe-art technology to complete caster revamping projects. In this paper concepts and references for short machine outages and fast caster ramp-ups at moderate investment costs are presented.

Jul 30, 2018

By Mirko Jurkovic, Thomas Hueper, Jens Kempken

The high competition scenario pushes the steel producers business. Zero defect requirements from customers force the operators for additional efforts in process control and quality management. PQA® has been developed as an advanced process and quality management assurance solution. It is focusing on the analysis of process data, equipment information, inline quality measurement devices and trend analysis. The paper describes the structure of the advanced process and quality management assurance solution PQA®; it gives insights on the expert know-how, process and quality evaluation and points out the benefits like cost reduction, improvement yield and customer satisfaction increase.

Oct 1, 2019

By François DUMORTIER

Due to the increasingly stringent requirements and the needs of the automotive industry, galvanizing lines for automotive products have to be modernized and improved. Beginning of 2017, SEGAL, a Tata Steel CGL located in BELGIUM and fully dedicated to automotive market, placed an order to increase the line capacity from 550kt/year to 600kt/year to process a wider range of steel grades and improve the product quality according to automotive requirements. To improve quality, a major revamping of the skin pass was necessary. The objectives were first to increase the work roll diameter from Φ560mm to Φ650mm to be able to transfer the required roughness with low elongation on soft material and second to increase the rolling force and tension to reach higher elongation on high strength steels. The result was the adaptation of the whole skin pass mechanics. Old mechanical elongation system has been replaced by a completely new single AC motor with helical gearbox at each bridle roll. John Cockerill achieved such complicated revamping in a very short time since the shutdown started only 6 month after the contract signature. The shutdown down schedule has been optimized with pre-erection works and the teams working 24/7 to implement all the changes. The complete project (skin pass, furnace, loopers) have been adapted during the three weeks shutdown. Today the customer can use both 560mm and 650mm work roll diameters. Thanks to the use of the new 650mm work roll diameter, the customer is able to make the same elongation using a bigger roll force (average 20% more), which has strongly improved the roughness transfer to the strip and the removal of the defects. SEGAL is really satisfied able to produce and supply higher quality automotive products to his customers.

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 Michel Rodrigo Luiz, Glaucio Augusto Polini, Leonardo de Souza Melo, Giovani Rodrigues, Giardini F. Lazzarin

ArcelorMittal's pickling and cold rolling line has been demanded to increase production since the installation of equipment in 2015. In addition to improving productivity related to these new equipment, several additional jobs were planned and executed on equipment already installed has been carried out in order to improve the efficiency of the line. The present work exposes what was done in the scale breaker (tension leveler) to improve the availability results of the section and consequently of the line.

Oct 1, 2019

By Peter Fajfa, Heinz Palkowski, Jakob Kraner, Matjaž Godec

The study of asymmetric rolling on the AA 5454 aluminium alloy plates was carried out. The plates were taken directly from the industrial hot rolled sheet. They were cold rolled on the laboratory mill with different rotation speed of the upper and the lower work roller with the strains around 33 % and 44 %. To get closer to the industrial conditions the maximal dimensions of the rolled plates for laboratory rolling mill and the special industrial lubricant were used. After deformation the plates were annealed to the soft condition. This research was focused on all possible effects of asymmetric rolling: The reduction of rolling force, the increase of strain at same set roll gap, bending of workpiece, finer microstructure, more heterogeneous textures and as a consequence of that better mechanical properties. The asymmetric rolling with favourable mechanisms in the deformation zone has created the material with the homogeneous hardness in the cross section and with lower anisotropy, which is crucial for improvement of formability properties of aluminium work hardened alloys and to get closer to properties of steels. In the presented paper the general impact and different effects of speed difference of rollers was investigated on cold rolled aluminium alloy. Obtained and analysed results explain the function of asymmetry in rolling process and the options to implement the asymmetric rolling in industrial plant.

Oct 1, 2019

By Francois Mignard

With a limited global steel production growth, automotive application market shows interesting volumes and trends especially in emerging countries. The recent period has again enabled Siemens VAI to confirm a position amongst leading suppliers of new plants serving high-end steel production in particular for unexposed and exposed automotive material. With a series of recent plant references in operation and under construction, relevant answers to such sustained level of performances are highlighted along the downstream processes. Designed for a wide range of applications, Siemens VAI processing lines includes advanced technological and state-of–the art equipment, among them, Solid state laser welder, Pickling Tunnel tanks, Skin pass mill and Tension leveller, Side trimmer with dynamic width adjustment, and new generation of Automatic surface inspection systems. With a continuous aim of driving improvements, Siemens VAI has also developed Global Quality Monitoring solutions notably through advanced software which provide just-in-time warnings and assist steel makers in the daily operation of their lines. As lifecycle partner, Siemens VAI offers solutions and services in metallurgical expertise from metallurgical modelling, through physical simulation on rolling, annealing and galvanizing processes, and enables Siemens to accompany our customers along with their project definition till fulfilment of highest market requirements.

Jul 30, 2018

By Marco Castenetto

Some of the most significant Danieli innovations in the field of long products are the: i) The EWR® system, through automatic continuous head-to-tail flash welding of billets at reheating furnace exit side, enables uninterrupted production of the mill for endless rolling of straight bars, wire rod and bar in coils. The process is particularly beneficial to wire rod and bar-in-coil mills as it enables production of “customized-size coils” (any coil weight according to specific Customer request) and with extra-high final coil weight, even starting from low-weight billets; ii) The Spooler process is based on twistfree winding of hot-rolled rebars into highly-compact/ultra-heavy coils featuring a unique cobble-free un-coiling capability. This enables high-speed feeding of the downstream cold-processing lines with hot-rolled spooled coils coming directly from the rolling mill without the need of any traditional off-line operation (such as de-coiling, stretching & re-winding). The system results highly beneficial both to bar-in-coil producers and to the downstream lines operators. The latest step forward is the combined application of these two systems that has made it possible for endless rolling of spooled bar in coils, enabling to cumulate the benefits of the two processes, particularly as far as transformation costs are concerned.

Aug 16, 2017

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 Michaela Böberl

State of the art sinter coolers are working based on the cross flow cooling principle. Thus, only a part of the thermal energy can be used for heat recovery application. The other part of the cooling air is brought unused to the environment. Furthermore, environmental regulation regarding dust emission and intelligent usage of exergy are getting stronger. Therefore, Primetals Technologies developed sinter coolers based on the counter flow principle. The cooling air passes the sinter bed in counter-flow direction enabling a direct heat transfer from the hot sinter to the air. The exhaust gas temperature can be maximized by using the total heat of the hot sinter. Due to the possible usage of the total exhaust gas amount, diffusive dust emission is reduced to zero. Two types of counter flow coolers are in the portfolio of Primetals Technologies. One type is based on a stationary shaft, in which the hot sinter is charged. The flow of the hot sinter is in vertical direction from top to bottom, in counter direction than the cooling air. The second type is a circular hopper cooler. The hot sinter is charged on top of a moving bed. At the bottom of the bed the sinter is discharged. The cooling air flows also from the bottom to the top, following the counter flow principle. Depending on the requirements, one of the two counter flow cooler types can be chosen for optimized and efficient cooling of hot sinter..

Oct 30, 2017

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 Christoph Sedivy

Industrie 4.0 is slowly but surely arriving in the melt shops. Furnaces are being equipped with more and more sensors, digital models are increasing the degree of automation, and information is being shared between different aggregates within the plant. Because the electrode control system plays a key role in electric steelmaking, it naturally assumes an important position in the melt shop’s Industrie 4.0 strategy. In addition to reliable, state-of-the-art core regulation functionality, monitoring and reporting tools and the ability to communicate with other equipment are also required. Therefore, the latest generation of our electrode control system, the Melt Expert, was developed based on Industrie 4.0 design principles. Intelligent plant condition diagnostics, performance monitoring, and user-defined reporting are essential modules in this new system. With these functionalities, electrode control systems are developing into the information and control center of the furnace. A newly developed software app brings most relevant process information to mobile devices. This feature allows steelmakers to keep an eye on the performance of their equipment anytime and anywhere. This paper describes the new features of the electrode control system and shares our customers’ operational experience. Our focus is on the practical aspects of plant status monitoring, KPI reporting, and diagnostic functionality as well as the improvements achieved.

Oct 30, 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 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 Alberto Tremea

The eddy current system is universally recognized as a most suitable method to point out discontinuities or modifications on the roll surface. The automation of the controls through the implementation of sophisticated equipments on the grinding machine has favoured its employment in the roll shop. A big effort is still going on to clarify the best way to promptly identify situations that could be really unsafe for the roll life. The results presented in this paper have been obtained through an intensive activity conducted in field by Innse Cilindri on work rolls of finishing stands of hot strip mills. The correct interpretation of the eddy current signals and a good calibration of the automatic system have allowed, in many cases, a substantial optimisation of regrinding practices.

Aug 16, 2017

By Edmar de Souza Silva, Antonio Augusto Gorni, Emanuelle Garcia Reis, Daniel Bojikian Matsubara

Controlled rolling followed by accelerated cooling, known worldwide as TMCP, aims to increase mechanical properties without toughness deterioration. The process principle is to promote the plate cooling with water jets along the range of the austenite transformation temperatures. The accelerated cooling process is only fully effective when controlled in an integrated manner, as it alone cannot ensure significant improvements in the final properties of steels. Plate surface quality depends on some parameters that must be controlled before the start of the plate accelerated cooling. Good flatness is essential to avoid irregular water accumulations during cooling. After the reheating process, the slab should have uniform temperature, uniform austenitic grain size and easily removable scale. The slab thermal and microstructural heterogeneities are inherited by the rolled plate and tend to increase further during the accelerated cooling. This results in flatness problems, high level of internal stresses and mechanical property variations. The descaling strategy is an extremely important factor and must be determined with great caution. It is important that scale thickness and distribution is uniform to ensure homogeneous cooling over the entire plate surface. Otherwise, there will be an uneven temperature distribution, which can cause serious problems of flatness, surface quality and mechanical properties.

Oct 1, 2019

By Edo Engel

Hot Blast Stove Technology has been developed to such an extent that low cost hot metal production for over 30 years without major repairs has become achievable, making the decision for a campaign length between 5 to over 30 years a design choice for the plant owner/operator. Some of the earlier examples of designs capable of such long campaign lengths are currently close to the 50th year of their running campaign. These examples are found especially in Europe and North America. Along the duration of these campaigns, repairs to subsystems such as burners, hot blast outlets etc. may be required. Depending on a plant’s up and down stream production capacities, the repairs may have to take place in the shortest possible time frame to minimize production loss. This article discusses an approach for intermediate repairs, executed while keeping the majority of the system at operating temperature.

Oct 30, 2017

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 Uazir Bezerra de Oliveira, Günther Staudinger, Michael Skorianz, Edo Engel

Oct 1, 2019