Search Documents

By Alessandro Marques

Based on a short overview regarding steel defects in the final product, several refractory approaches to maintain or increase steel cleanliness are reviewed in this publication. By applying a ladle to mold approach, one potential to maintain cleanliness is to reduce the probability of air ingress by selection of a suitable slide gate system. Following this path, also the influence of a special configured impact pot is presented to maintain steel quality. Finally, higher productivity as well as cleanliness can be provided by selection of PROIL as a revolutionary product at the casting machine.

Oct 30, 2017

By Patrícia Mundim Campos Faria

The process of particle size reduction by grinding is inherently inefficient and involves high capital and operating costs. In particular, ball milling is one of the important unit operations in the iron ore pelletizing process. The mill product, due to its physical properties, determines the efficiency of subsequent stages of classification, filtration and pelletizing, thus impacting the quality of iron ore pellets. The work demonstrates the application of the population balance model in the optimization of a full-scale ball mil circuit grinding pellet fines with the aim to evaluate the optimal solids concentration to improve iron ore pellet quality. Initially, detailed experimentation was carried out in a 25.4 cm diameter batch mill and a relationship for mill scale-up using a linear population balance model in wet grinding systems was established. The selection and breakage parameters and the specific selection functions were determined for pellet feed iron ore. It was possible to identify the non-normalizable nature of the breakage functions of the ore studied, which were modeled properly. Afterwards, as a result of incorporating the specific selection functions and breakage functions into the linear population balance model, it was possible to predict product size distributions in the pilot and plant scale mills (0.416 and 5.18 m diameter, respectively) from data obtained in the 25.4 cm diameter mill. Finally, with this scale-up procedure it was possible to appraise the plant scale optimization via laboratory scale grinding mill tests. The effects of changing percent solids were assessed in order to improve the industrial mill performance and the optimal value should be in the range from 76 to 80%.

Aug 1, 2018

By Roberto Balarini Junior

Tribological behavior of Si3N4 balls sliding against Al2O3 discs in water was investigated by studying the influence of parameters such as initial surface roughness and circular axial run-out of the discs. The objective was to relate these parameters with the occurrence of the phenomenon known as ultra-low friction coefficient (ULFC), which is characterized by µ < 0.01, including the correlation with running-in duration. As a general trend, greater initial surface roughness and circular axial run-out resulted in greater running-in duration. In addition, it was verified that a mixed lubrication regime (hydrodynamic and boundary) is required to guarantee the occurrence of ULFC by comparing the calculated minimum film thickness with the composite roughness of the worn surfaces. Also, ICQ-OES analysis of the water after the tests indicated that a silicon concentration greater than 1.3 mg/l should be fundamental for the occurrence of µ < 0.01.

Jul 31, 2018

By Patrick E. Connell

During the ABM Conference of 2015 the latest design and process features of the new 3-roll RSB® generation were presented together with a unique Size Control System SCS® for a real time closed loop control to produce an extraordinary quality SBQ – day in, day out. In the past two years, Kocks has focused on improving the repeatability of the rolling process and developed technology to enhance the performance of its equipment. These developments include Fast Remote Control (FRC), Stands Adjustable Under Load (AUL) implementation of closed loop Size Control System (SCS), and finally a state of the art laser Gauge (4D Eagle) that pulls all of these developments into a complete package of quality. Gauges used in the past generally operated with the “shadow” measuring system. The latest gauge developments are based on the “light section” method. This method is more suitable to provide real time measurement parameters of the rolled bar. Placed close to the last rolling stand, the “light section” gauge is capable of measuring around the complete diameter with a clear definition of the bar stage in relation to the axes of the rolls. It is also capable of making these measurements using a very high measurement frequency. Following requirements of the market, requiring the highest gauge measuring frequencies which display the bar in the most accurate way even at the highest rolling speeds, the “4D Eagle” gauge was developed. This paper describes all the process features and parameters of this impressive and unique newly developed gauge as well as the other described technical improvements.

Oct 30, 2017

By Pedro Jorge Walburga Keglevich de Buzin

The steel production in mini mills generates several process residues, among them the electric arc furnace dust (EAFD). This residue has as main elements Fe, O, and Zn, being classified as hazardous by the presence of Pb and Cd. In recent years, a rise in the chlorine content of this residue was observed, motivated by the increased use of scrap with impurities bearing this element. In this work, a qualitative assessment of the presence of chlorine in the electric steelmaking process is made. Complementing it, theoretical considerations based on the computational thermodynamics tool FactSage show the effects of the chlorine on the mineral species in EAFD and on gaseous species in the gas phase (HCl and Cl2). For this study, PVC polymer was used as the chlorine carrier substance which contaminates the EAF charge; presence of other minor elements in the system such as K, Na and Pb were also considered.

Aug 7, 2018

By Kazuya Nakabo

In this article, influences of restraint and MgO content on densification of alumina-magnesia castable during heating were experimentally studied. High thermal expansion-alumina-magnesia castable specimens were surrounded by low thermal expansion-alumina-silica castables, and heated in an electric furnace. Doing so allows restrained heating of alumina-magnesia castable. According to the results of simple calculations, the restraint stresses were estimated to be between 2 to 20 MPa, so the experimental conditions were considered reasonable. As a result of the experiments, it was verified that restraint densifies alumina-magnesia castable, resulting in an increase in modulus of rupture and modulus of elasticity. The densification effect of restraint became larger as the MgO content increased. The effects are attributable to an in-situ spinel forming reaction, which improves corrosion resistance.Taking the temperature distribution in the castable lining into account, large restraint stress is expected for the hot face while only a little effect is expected for back end. Thus, excessive difference in material property in the thickness direction, which is undesirable in terms of structural spalling, is a concern.Hence, the MgO content of alumina-magnesia castable should be determined carefully, taking not only corrosion resistance but also spalling resistance into consideration.

Oct 30, 2017

By Fábio Dian Murari, Antônio Adel dos Santos

The effect of reheating temperature of slabs on the precipitates dissolution and mechanical properties of Ti-Nb microalloyed steel was investigated in pilot scale. It was verified, by means of transmission electron microscopy, a significant decrease in precipitates formed during the solidification of the steel as the reheating temperature increased from 1100°C to 1200°C. No significant changes in size and shape of the precipitates were observed with further temperature increase up to 1280°C. In line with the precipitates dissolution behavior, an increase in strength was observed with the elevation of the reheating temperature up to 1200°C, due in part to the reprecipitation of fine Nb-rich precipitates during the hot rolling. At 1200°C the presence of deformed ferrite on the microstructure contributed to the additional increase in strength. After reheating above 1200°C up to 1280°C, a decrease in strength of the rolled plates was noticed. This effect has been credited to the absence of deformed ferrite grains and also to a small increase in the low angle grain boundaries size. The results were in agreement with Thermo-Calc and Dictra simulations.

Oct 1, 2019

By Bi Zongyue, ZhangYongqing, NiuTao, Guo Aimin

Over the past twenty years, significant advances have been made in the field of microalloying steels and associated applications, among which one of the most successful application cases is development and application of heavy-gauge X80 coil with high temperature processing HTP practice used for China's Second West-East pipeline, the longest X80 pipe in the world. During this process, HTP design concept has been sucessfully applied to develop 18.4mm X80 coil with demanding low-temperature fracture toughness requirements. In the meanwhile, China's metallurgical workers have further optimized HTP design concept with the aid of powerful rolling mill and coiling equipment, and made it possible to develop 21.4mm X80 coil used for Russia-China East line. In the paper, we would simply review the development history of high-strength pipeline steels, and then give more priority to the fundamental points for sucessful development of 18.4mm X80 coil and SSAW pipe, which paved the way for subsequent development of 21.4mm X80 coil and SSAW pipe. Finally, we would present the test results of mass production and burst tests, and dispel the suspicion that SSAW pipes made of X80 coil are more qualified to resist ductile fracture.

Oct 1, 2019

By J. Bas A. F. Smeulders

Traditional laboratory lubrication tests, including those for cold rolling lubricants often involve measurement of neat oils. To achieve increased levels of test severity, such tests are often carried out at high temperatures and prolonged durations. However, we found that the levels of lubricant degradation and wear in these tests can be much higher than in the field. Moreover, steel rolling is not done with neat oils, but with emulsions, where the presence of water influences film formation, surface chemistry and oil composition in the roll bite. To better approach the situation in the field, and thus to be able to develop rolling oils with improved lubrication performance, several lubrication tests were developed for emulsions: direct measurement of film formation and measurement of Stribeck curves, in which the emulsions can be assessed in terms of their boundary lubrication and elastohydrodynamic behaviour. The key innovation is that also another test method was developed, which focuses on boundary lubrication and wear, and the role of extreme pressure and anti-wear additives. Realistic levels of test severity are achieved in the tribometer by mimicking frictional power intensities and flash temperatures for typical cold rolling or tinplate mills. Test conditions can be adapted according to the mill stand or pass number and other cold rolling process parameters. The emulsions are kept at normal operational temperature. Clear differences could be observed between emulsions of various concentration and composition. The viability of the method is illustrated by a number of field cases, in which a good correlation is demonstrated between the laboratory tests and the performance in a pilot or production mill.

Jul 30, 2018

By Karl Berger

The paper gives a comprehensive overview of the historical development of various metal rolling technologies and also describes the influence to industrial and socio-economic developments. The rolling of steel, in particular of rails, beams, rebar, strip and plate has enabled the large scale transport and travel, the building of bridges and buildings, the manufacturing of ships and cars. All this has changed the face of the world significantly. Further the paper approaches technological highlights in the design, manufacturing, drive and control of modern mills and the various types developed to create industrial economic units for the different markets and customers’ requirements. An outlook of future challenges is as well discussed in the paper. Various solution approaches for the rolling technologies, from continuous improvement of existing plants to more radical new concepts like endless rolling, near net-shape casting and rolling are approached. A positive conclusion is drawn that rolling technologies will remain a valuable area for engineers with scientific and economic challenges, but also a clear vision for positive contribution to further industrial and social development.

Jul 30, 2018

By Massimilinao Svetina

In 2010 Danieli & C. S.p.A. put into operation a new Pickling Tandem Mill in Cremona (Italy) at Acciaieria Arvedi, the last Pickling line coupled Tandem Cold Mill (PLTCM) in Europe. The plant was tailor-made to suit the specific requirements of this customer; a very broad range of sizes and grades (IF to AHSS as well as DP and TRIP1000) including ultra-thin hot band can be processed, achieving a total capacity of 1.6 Mt/y. The Danieli & C. S.p.A. Turboflo® process was selected because of its proven efficiency and ability to handle ultra-thin gauges at speeds exceeding 400 mpm in the pickling tanks. All the equipment, i.e. pickling section and rolling mills was provided with the last generation of Danieli market-oriented technologies. Danieli & C. S.p.A. - with the support of Arvedi and feedback from the field - is continuously improving its technical design solutions and optimizing plant operations.

Aug 16, 2017

By Dr. Steven G. Jansto

The market demand for reduced fuel consumption and CO2 emissions in the automotive, energy and construction sectors have further increased the demand for new and advanced higher quality microalloyed grades produced via TMCP. The technological integration of the process and physical metallurgical advancements of value-added niobium (Nb) microalloyed thermo-mechanical controlled process (TMCP) steels continue to be developed and is an important element for these more demanding end user requirements and cost-effective steel production. The reheat furnace process step has a profound effect on the TMCP performance, final hot rolled steel quality and mechanical property consistency during the production of hot rolled steels. The uniformity of heating applied across the entire width, thickness and length of the slab or billet is essential in the successful achievement of consistent customer properties regardless of the chemistry. The resultant ferrite grain size in the final hot rolled product is significantly governed by the initial prior austenite grain size. However, the transition from laboratory melted and TMCP hot rolled heats to the production scale is often quite challenging. Aberrations in the reheating process step at the industrial furnace are often the root cause of mechanical property quality issues. These combustion process metallurgy parameters connect directly to the resultant TMCP product quality and is defined as Combustion Metallurgy

Oct 1, 2019

By John Ross Middleton

Based upon 30 years+ experience in the Development, Implementation and Ongoing Support of Computer based Melt Shop Management Systems in about 40 plants in the UK, Europe and the USA, consideration of the overall facilities of a state of the art, comprehensive, Integrated Melt Shop System covering Melting and Secondary processes for all grades of steels and superalloys; the scope of functionality of these systems, covering Raw Materials and Consumables Procurement and Inventory Management, Laboratory Management, Melt Shop Scheduling, Furnace Charge and Additions Optimisation, Level 1.5 to Level 2.5 Materials Optimisation and Process Control Calculations, Process Data Recording, Management of Ladles, Furnace Bodies, Vessels and Moulds, Comprehensive Management Reporting and Integration with Corporate ERP Systems. The second section of the paper reviews the key &lsquo;Success Factors&rsquo; to achieve rapid, successful implementation, comprehensive, fast response user support, continuing system improvement and maintaining &lsquo;perfect fit&rsquo; of system to operations in an ever changing future technical, operations and business environment.

Jul 29, 2018

By João Luiz do Vale

In standard wear tests, such as pin on disk (ASTM-G99) or block on ring (ASTM-G77), the apparatus simulates conditions that are often different from a machine element real application. Therefore, for an accurate investigation of a tribological application, it is essential to test the real condition in which there are similarities as: geometry, contact details, force application mode, materials, among others. It emphasizes that for studies involving polymeric materials it becomes extremely relevant. Thus, the Laboratory of Surfaces and Contact (LASC) at UTFPR developed an apparatus for sliding bearing on shaft test. In that equipment, loads are applied by a dead-weight system and the frictional force is measured on a load cell. The apparatus operating ranges for load added to the dead weight system and rotation shaft are from 0.2 to 5.0 kgf and from 260 to 3500 rpm, respectively. This paper presents a detailed evaluation of such apparatus, which includes free-body diagrams analysis and a deduction to obtain an equation for the kinetic friction coefficient. Also, the standard measurement uncertainties of a caliper, an electronic scale, and a cell load were determined. It was verified that the kinetic friction coefficient equation is dependent on the apparatus geometry, the applied load, and the frictional force value. Additionally, through the statistical significance analysis it was concluded that some terms in the equation were not significant. Finally, through the application of the error propagation theory in the kinetic friction coefficient equation, the standard measurement uncertainty of the apparatus which showed a value nearby 0.002 along the operating range of the apparatus was obtained.

Jul 31, 2018

By Christoph Aichinger

A smart combination – Primetals Technologies developed the Circular Pelletizing Technology (CPT), which is a combination of the well-proven travelling-grate pelletizing technology with the design of a circular dip rail cooler of modern sinter plants. The overall space requirement and the installed weight for a CPT plant is significantly less compared to conventional technologies and by that CPT is a very attractive alternative for new projects.

Aug 16, 2017

By Edo Engel

Blast furnace No. 3 at Zaporizhstal in Zaporozhye is rebuilt in 2016-2017. The Ukrainian company is targeting increased production and availability, mainly through the use of new technology. Zaporizhstal awarded a contract for a new Top Charging Unit to Danieli Corus, after comparing all available technologies. Reliability of the chosen charging device is pivotal, since long outages may be required for maintenance/replacement jobs, which strongly affects the availability of the blast furnace. This article describes the Top Charging Unit including DANCU (Danieli Charging Unit) - a robust hydraulic system. The main focus employed by Danieli and Danieli Corus during the development of this system has been availability and maintainability of equipment. This chute type charging unit has only few major moving parts, none of which is complex or vulnerable. The article also describes the main challenges of the project at Zaporizhstal, such as the use of hot sinter.

Oct 30, 2017

By Jörg Busch

The essential pre-requisite for attaining the high quality of product required from high-speed continuous production processes is the use of new measurement and control technologies. High availability and reproducible measuring results ensure the high level of process stability necessary for full continuous operation. The requirements for the optimisation of quality across the complete production process and for quality analysis systems will be discussed. This report will present examples of basic and new measurement technologies in Cold Rolling Mills and Processing Lines. The following gauging systems will be discussed in detail: Strip tension meter, roll force measurements, weighing systems and shapemeter rolls. The measuring and control systems in this presentation must be seen as high-tech solutions in the field of processing technology. The measuring methods and technologies described are, together with optimised process models and precision control loops and actuators, the main pre-requisites for achieving the quality of product required from high-speed continuous production processes. Interconnected quality management systems enable optimisation across the complete production process.

Jul 30, 2018

By Wolfgang Oberaigner

Primetals Technologies has always been a driver of innovation in steelmaking, especially by providing sophisticated process expert models for continuous casting machines. This capability is demonstrated by recent advancements in automation solutions that include: DynaPhase, Dynacs 3D, and DynaGap. This state-of-the-art suite of dynamic secondary cooling and soft-reduction packages take into account thermodynamic effects such as shrinkage and phase transitions, and thereby significantly contribute to direct quality improvements during the solidification phase in the continuous casting process. Speed Expert calculates an optimum casting speed for every casting situation, and additionally recommends a strand speed so that the point of final solidification is positioned at the end of a segment for optimum soft reduction. In the case of steel grade changes, the Intermix Expert precisely calculates the chemical properties of the mixed steel, thereby minimizing losses due to deviations from required specifications. The Nozzle Expert is a new model that detects clogged nozzles and broken hoses in secondary cooling systems. The first installations were highly successful and customers are pleased with impressive reductions in maintenance costs and improved steel quality. This paper describes these innovative process automation solutions and gives an overview about the successful results achieved within the first installations.

Aug 16, 2017

By Andreas Jungbauer

Two Arvedi ESP plants going into operation in 2015 will allow a Chinese steel producer to better serve the extremely attractive local and export markets for high-quality, thin-gauge strip products. The energy consumption and the related costs are reduced by up to 45% compared to conventional casting and rolling processes. This also means a major reduction in CO2 emissions. The new plants are designed for an annual production capacity of 2 x 2.55 million tons of high-quality, ultra-thin, hot-rolled strip products with widths of up to 1,600 mm and thicknesses down to 0.8 mm. The project scope also features a comprehensive training and assistance package for plant start-up and operations by personnel from the existing ESP plant at Acciaieria Arvedi SpA, Italy. The plant setup, the trainings and assistance program as well as latest results from the ESP plant in Italy will be presented. While this project is under execution three further ESP lines have been ordered by the same customer summing up now to five ESP lines at the same location.

Jul 30, 2018

By Bernhard Hiebl

Global trends that are constantly challenging the iron and steel producers are related to worsening of the iron ore grades, higher substitution rates of main iron ores to cheaper raw materials due to economic pressure and increased environmental standards. Changing the raw materials in an operating plant can significantly influence the sintering or pelletizing process. Adjusting all process parameters to regain stable and high productive operation takes considerable time and causes production losses. Furthermore changes in raw materials lead to variations in the process gas flows and emission concentrations.Therefore SVAI developed two models for numerical simulation of sintering process and pelletizing process. Amongst others the models are based on Ergun equation and include chemical reactions of the related process. For already operating plants the simulations shall predict changes of the process parameters when raw materials are exchanged or when operational parameters are varied. Furthermore the simulations give advantageous information for the design of green field plants and allow the simulation of different plant configurations.The objective of this paper is to demonstrate what the latest developments are in these numerical simulations and what Siemens VAI is doing to overcome the remaining challenges in this field.

Aug 2, 2018