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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 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 Rodrigo Ribeiro de Andrade, Túlio César Nogueira, Ed Juarez Mendes Taiss, Nilton José Lucinda de Oliveira

The objective of this study was to determine the effects of an eventual slab central macro-segregation in microalloyed steels with low Mn content (0.80%) and high Nb content (0.08 to 0.10%) on the kinetics of recrystallization of austenite during its rolling, on its critical temperatures, that is, of non-recrystallization (Tnr), start Ar3 and finish Ar1 of ferrite transformation and its response to a simulated industrial thermomechanical processing. The determination of the austenite recrystallization kinetics was made through isothermal double compression tests using a dilatometer, while the critical temperatures were determined through hot torsion tests in a Gleeble® 3800. It was found that austenite recrystallization kinetics, Ar3 and Ar1 temperatures did not present significant changes for the samples extracted both at ¼ of the thickness and at the core of the plate, indicating that, as expected, the central segregation in this type of steel was not intense to the point of affecting this phenomenon. The Tnr values determined for the samples extracted in the core of the plate were, on average, 30°C lower than those obtained from specimens extracted at ¼ thickness, which suggests that a significant portion of the carbonitrides present in the core of the slab are eutectic and coarse, not having completely dissolved during the reheating of the specimens. This occurred despite the fact that the austenitization temperature adopted in this treatment theoretically leads to the total dissolution of Nb, as seems to have occurred in the case of specimens extracted at ¼ of thickness, where carbonitrides have a finer size.

Oct 1, 2019

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 Mohammad Masoumi

In the present study, API 5L X70 pipeline steel samples were deformed by hot-rolling cooled in air or quenched in water and subsequently tempered at different temperatures. X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) technique were used to analyze the texture evolution from the initiate state to rolling and tempering state at mid-thickness and near surface plane of all samples. The results showed that the mid-thickness region is richer in {100}//ND oriented grains known as more susceptible to crack formation and growth through. Hot deformed specimen showed dynamic recrystallization grains while quench tempered sample at 700°C evidenced recovery and grain growth.

Aug 16, 2017

By Alessandro Pigani

Over the last 25 years the thin slab casting and rolling process has been gaining a major market share in the production of hot rolled strip, progressively eroding the areas previously of exclusive domain of conventional mills. This is mainly thanks to the competitiveness of the process over conventional ones, and to the growing ability of this technology to cover the majority of market niches, well beyond the boundaries of the commodity market. After having significantly contributed to the continuous expansion of this production mode and after an extensive campaign of theoretical research and physical testing in reference plants, Danieli has progressively developed over the years a new generation of thin slab casting and rolling layout, marking a new phase in the evolution of this process. The new step-ahead is epitomized by the name QSP-DUE. This configuration belongs to the Quality Strip Production (QSP) family, which is Danieli’s strip-quality-oriented thin slab based plants. The innovative features of the process are embodied in the acronym DUE, which stands for Danieli Universal Endless (Danieli patented technology – US patent n. 8087449, January 3rd, 2012). What makes this new concept different is the ability of “universal” rolling modes thanks to the fact that, now, within one single plant it is possible to perform coil-to-coil, semi-endless and endless rolling modes, making this plant a major technology innovation compared to the previous generation.

Aug 16, 2017

By Bernardo Siqueira

This paper presents a unique stirred milling technology, Outotec HIGmill™, a modern, flexible and energy efficient grinding solution for fine and ultra fine grinding being tested in an industrial scale level. The test was performed at an iron ore pellet producing plant in Sweden (for confidentiality reasons, it will be referred to only as “the client”) where a pilot HIGmill™ unit (HIG25) was installed parallel to a conventional regrind circuit to compare its performance to the existing ball mill. By using a continuous test run procedure and evaluating the parameters of F80, P80, mill shaft rotation speed and power drawn it was determined its grinding capabilities, operational flexibility and energy efficiency. Outotec HIGmill™ outperformed the existing ball mill in the plant proving its capabilities to grinding finer, with steeper particle size distribution (PSD) and much higher energy efficiency. The tests performed showed that, with further refining of its operation, it is capable of consistently deliver the required PSD with up to 30% higher grinding efficiency.

Aug 16, 2017

By Jose Maria Rodriguez-Ibabe, Ronaldo Antonio Neves Marques Barbosa, Douglas Glenn Stalheim

Major costs in the production of both flat and long commodity grade structural steel products include alloy, labor and energy. Flat and long commodity grade structural steels such as ASTM A36, ASTM A527Gr50, S235, S275, S355 and other equivalent world societal standards represent over 500 million annual tons worldwide. These simple commodity grades consist of a minimum of three base common alloying elements, carbon, manganese, silicon and then can be supplemented with microalloying elements of either vanadium or niobium. Since 2016 raw material costs for two of the five alloying elements in these commodity grade structural steels, FeMn and FeV, have risen significantly and/or have become volatile making it difficult to maintain stability in profitability for these commodity grades. For steel plants producing hundreds of thousands and in some cases over a million tons annually of these common structural steel grades because of the significant alloy cost increase for Mn and V alloy additions has squeezed profitability of these grades. These grades typically represent the base loading for cost controls in most all steel plants and hence a significant cost increase or volatility in two of the five elements used for these grades having a negative effect on overall production costs. However, with a proper strategy for alloy designs working in conjunction with the mills existing processing capabilities to achieve the desired end metallurgy/mechanical properties, alloy costs and operational efficiencies can be realized.

Oct 1, 2019

By Osvaldo Guilherme Comineli

An extensive investigation into the role of low copper contents on the hot ductility of C-Mn-Al steels has been carried out in order to better understanding the problem of “hot shortness”. Previous work has suggested that this problem results from the build up of Cu that occurs at the surface of the steel as a consequence of the preferential oxidation of iron. This causes the formation of a Cu-rich film of low melting point. A nickel addition has been reported as a solution to the problem, since it increases the solubility of copper in the austenite. After hot tensile testing to failure, samples of Cu-containing steels have been examined using optical, scanning and transmission electron microscopes. Recently published results indicate that copper, in addition to precipitating out as CuS, also segregates to MnS inclusions forming a shell around them. This does not seem to impair the hot ductility under an inert atmosphere, but may have serious consequences under an oxidising environment and lead to “hot shortness”. The influence of nickel in improving the hot ductility seems to be due to it forming a higher melting point alloy with the segregated copper. Data from this incomplete work also suggests that Ni reduces the precipitation of CuS particles. Current investigation carried out using confocal microscopy still to be completed will improve the understanding of the role of copper and nickel on the problem of “hot shortness”.

Aug 8, 2018

By Thomas Höfler, Michael Auinger, Bernhard Linder

Gas-fired pusher furnaces are commonly used to heat steel slabs before hot rolling. Temperatures well above 1000 °C combined with an oxidizing atmosphere containing H2O, CO2 and O2 result in rapid oxidation of most steel grades. The resulting oxide scale and the chemistry of the metal-scale-interface are major determining factors for the occurrence of hot rolling defects. To better understand these phenomena, lab-scale trials were performed with two different steel grades in an electric tube furnace in the temperature range 1000-1250 °C, using an atmosphere of about 20 % H2O, 7 % CO2 and 3 % O2. Humidification of the gas was achieved by evaporation, using a custom thermostat with standard laboratory glassware. The resulting samples were prepared metallographically, using cold mounting under vacuum with taper section angles, and analyzed using light microscopy and SEM/EDS. The scale structure of the Si alloyed steel was highly dependent on the oxidation temperature due to the formation of eutectic liquid phases of FeO, Fe2SiO4 and FeAl2O4. Below the eutectic temperature, the scale of the Si steel appeared to be made up of three distinct areas: The external scale consisting solely of Fe oxides, the internal scale containing Fe2SiO4 and FeAl2O4, and an internal oxidation zone with SiO2 and Al2O3 in a mostly plain Fe matrix. Comparisons of the experimental results with simulations of the internal oxidation showed good qualitative agreement.

Oct 1, 2019

By Hiroshi Ichikawa

In 2013, Nippon Steel & Sumikin Engineering Co., Ltd. (hereafter referred to as NSENGI), Tenova HYL and Danieli have entered into an agreement to combine ENERGION DR technology into blast furnace technology and/or with syngas technologies. This new alliance will allow the three companies to combine research and development activities with their respective expertise in ENERGIRON DR technology, Blast Furnace technology and Syngas (by-pro gas and coal gasification) technology, with the ultimate objective to develop breakthrough iron making technologies and create such EPC projects. This paper introduces the concepts and the features of our breakthrough technologies of combining of ENERGIRON DR technology, Blast Furnace technology and Syngas technology.

Aug 16, 2017

By Túlio Magno Fuzessy de Melo, Luciano Santos Marques, Vicente Tadeu Lopes Buono

The influence of the coiling temperature after hot strip rolling on the microstructure and on the tensile and hole expansion properties of a 800 MPa multiphase steel was investigated. For the temperatures between 150°C and 600°C the microstructure consisted of a ferritic matrix with a dispersion of fine martensite-austenite (MA) and regions of degenerated upper bainite. In all cases the ferrite presented a heterogeneous mixture of polygonal, quasi-polygonal and acicular grains. The yield and tensile strengths showed a tendency of decreasing with the increasing coiling temperature, probably because of the larger fraction of MA particles at lower temperatures and higher fraction of quasi-polygonal ferrite at higher temperatures. The elongation was not significantly affected by the variation of coiling temperature. The average hole expansion ratio showed a maximum of 80% for the material coiled at 400°C and fell below 50% only for the coiling temperature of 150°C, probably due to the larger hardness difference between the ferrite matrix and the MA particles.

Oct 1, 2019

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 Vitor Guarnier Domiciano

Pre-shaped refractory burner blocks play an important role in reheating furnaces operation and melt shops production since they are responsible for heating the billets/plates so that they reach the temperature required for lamination. This paper presents the main characteristics and properties of a new refractory castable developed for pre-shaped burner blocks, which significantly improved the performance of reheating furnaces burner blocks. Tests carried out in 3 different melt shops have shown that the new refractory castable was able to extend the service life of the refractory burner blocks from 1 year (standard product) to more than 3 years (new castable), showing perfect conditions to continue operating for a longer period.

Oct 30, 2017

By Carlos Martins de Oliveira

The trucking industry is constantly seeking improvement and cost reduction of their vehicles, studying new lighter and robust materials to meet the needs of its customers. The objective of this work is to study the application of DCPD Telene, PU. R. RIM and PP-TD 20 materials in aesthetic components of trucks: bumper, calender, upper and lower bracket and side air deflector. A multifunctional work team was created to work in such parts of IVECO trucks. The work began with an analysis of possible improvements to the current parts and followed the subsequent phases: definition of new materials, virtual modeling, new tools, and durability test in vehicles. It could then be verified that the proposed DCPD Telene, PUR. RIM and PP-TD 20 materials showed greater strength, better painting surface, and reduced weight and cost in parts.

Aug 8, 2018

By José Aparecido Pereira

The customer asked for a 5” angle roll pass design. For this angle, in a normal pass design, a 160mm billet is required. For the production of this billet would be necessary a new 160mm mold for the Continuous Casting Machine, which produces 150mm billets, increasing the complexity of the melt shop. The rolling mill is designed to produce angles up to 4", technical information recommended the replacement of a gearbox because this process would generate torque up to 15% above nominal. An innovative roll pass design was done using 150mm billet using the Aparecido-W Method that cause a higher spread in the first three passes, thus reaching the desired leg length. As this method is not used in any other known rolling mill, a FES (Finite Element Simulation) and FEM (Finite Element Modeling) was done by a Research & Development center which demonstrated that the design was viable. From July, 2018, three tests were done being produced around 700 t of good quality products without difficulty of set up. The rolling mill team carried out this project at a very low cost and in record time of five months. The average torque of the motors was 36%, without overload for the equipment.

Oct 1, 2019

By Juliano Braz Possatti, José Fagundes Júnior

This project involved a teamwork including process control, maintenance and operation specialists, R&D and CTO experts to identify and actuate on each opportunity to increase charging temperature, furnace efficiency, decrease discharging temperature when possible, decrease FM and RM cycle time (mainly speed increase and interpass time decrease), tracking zones optimization, safe use of equipment power limits, safety interlocks revision and tune models for Mill Pacing Control and Slab Design.As result of these efforts, ArcelorMittal Tubarão HSM today occupies a prominent position among the best HSM of similar layout and produced mix of the group and worldwide. This paper will show the path which was followed by the AMT HSM team to achieve more than a 20% productivity increase resulting in a hot coils production per year more than 700 million tons higher.

Oct 1, 2019

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 Silvio Cecchini

State-of-the Art Mould Level Control Solutions for continuous casting applications face different challenges. On the one hand, technological phenomena such as clogging and unclogging, unsteady bulging or waving can create unpredicted meniscus disturbances by completely changing the casting channel geometry and the flow behaviour of liquid steel to the mould. On the other hand, from the viewpoint of caster operations, long lifetime, quick interchange-ability and integration capability into existing systems must be achieved. In the present contribution, the overall development of INTECO TBR’s mould level master – a comprehensive mould level control solution for all continuous casting applications – will be introduced. The basis for the presented system is a development over several years which includes investigations of all critical components such as shroud, stopper, stopper mechanism, servo actuator and mould level control program. These investigations finally resulted in a new-ly developed control algorithm for a highly dynamic servo actuator. The control algorithm with its basic functionality such as the prevention, identification and removal of clogging impacts with the associated automation functions to reduce their influence onto the overall mould level control performance will be presented. The scientific basis, the resulting control functions and their related automation implementation will also be illustrated. Finally, a patented control algorithm and control functionality for unsteady bulging and waving effects with the associated automation functions to reduce their influence onto the overall mould level control performance.

Aug 16, 2017

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