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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 George Schipper, Peter Gelten, Pepijn Adriaen, Hugo Uijtdebroeks

Tata Steel IJmuiden Hot Strip Mill 2 (HSM2, 5.5 Mtonnes/yr) is currently being upgraded, resulting in an increased rolling force and motor power capacity. With the current conventional work roll spray cooling, a deterioration in work roll & strip surface quality performance is expected as a result of the increased mill capacities. In order to improve strip surface quality, HSM2 decided to do a full-scale production trial with High Turbulence Roll Cooling (HTRC) at stand FM2. HTRC is a novel way of roll cooling using a high turbulent flow regime. HTRC is positioned very close to the roll surface and gap exit, which is beneficial for the roll surface quality. It is operated at a high flow rate but at a low pressure. HTRC not only significantly improves the roll surface quality, in addition, it makes high pressure pumps, needed for the conventional spray cooling, redundant, leading to substantial savings on electricity costs and thus CO2 emissions. HTRC is in trial operation since 7 August 2018. Results show no operational issues, an excellent roll surface quality and an increased cooling efficiency. In summer 2020 stands FM1-FM2-FM3-FM4 of HSM2 will be equipped with HTRC.

Oct 1, 2019

By Woo, Hur, Kim, Ki Nam, Seung Min, Kyoung Sik

Tandem cold mill (TCM) is a process to obtain flatness as well as thickness desired by the customer by rolling hot-rolled coils continuously. The final stand of the TCM plays the most important role of flatness control, which usually uses the real-time measurement at the exit. However, as the material property increases, it is not easy to handle flatness with only the final stand. In order to overcome such a limitation, we propose a feedback control method to strengthen flatness control for non-final stands. The proposed method was tested in an actual production line, and the effect is proved for 45K or less steel grade.

Oct 1, 2019

By Leszek Maldzinski

The present concept assumes carrying out the process of controlled nitriding with NH3 alone. This is a simpler process than that using two-component mixes of ammonia diluted with N2 or NH3diss. The regulation of the chemical composition of the atmosphere in the retort, and therefore the regulation of the nitriding potential KN, is obtained through the variation of the inflow rate of NH3 into the retort. What is a completely new things in a relevant process, the inflow of NH3 into the furnace is at times reduced to zero, which widens the range of the gas composition in the retort (and by the same token, of KN). The amount of NH3 introduced into the furnace is regulated (controlled) with the aid of a gas analyzer (for example an infrared analyzer). The gas analyzer opens and closes periodically the NH3 inlet valve with a frequency maintaining a desired gas composition (a desired KN) in the retort. The concept was based on experimental and theoretical investigations in term of thermodynamic and kinetic of gas nitriding. Investigations were carried out in a laboratory furnace with a quartz tube and also in an industrial furnace with a steel retort and a circulating fan. Nitriding was performed using NH3, NH3+H2, NH3+NH3diss. mixtures. In an industrial furnace the supply of NH3 into the retort was periodically closed, though with an operating circulation fan. The studies demonstrated that the growth rate of nitrided layer depends only on the composition of the atmosphere, (or KN), in the retort. It depends neither on a type of atmosphere introduced into furnace (NH3, NH3+NH3diss. or NH3+H2) nor a type of furnace (laboratory with a quartz tube or industrial with steel retort and fan). The results proved also that entirely closing of NH3 supply to the retort does not affect the growth rate of nitrided layer. A detailed analyses of the results was performed in a paper.

Aug 16, 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 Danilo Gonçalves de Oliveira, Rogério Martins Pereira

Chatter is a widely studied vibration phenomenon that affects most cold mills around the world and its impact on these lines are tremendous: from productivity and quality losses to mechanical equipment damage. The investigation of its origins and how to minimize the occurrences and their impact on the equipment require special instrumentation and algorithms in order to have a detection of the vibrations as soon as they start. This paper presents three methods of identification of chatter on a Tandem Cold Mill and the actions to leave the vibration frequency range before its amplitude achieve catastrophic values.

Oct 1, 2019

By Markus Reifferscheid

Industry 4.0, Digitalization, Internet of Things (IoT) and Cloud Computing are predominant topics in the world economy at the moment. At the ABM week 2017 Dr. Markus Reifferscheid, Head of Research & Development of SMS-group, will talk about the proceeding digitalization in the steel industry with selected examples of SMS-group. He will present advanced concepts and solutions which are currently being developed.

Oct 30, 2017

By Marcel Antonio Arcari Bassani

In the mining industry, it is common to have data collected in various formats. In an open pit mining operation, at the early stages of exploration samples are obtained from diamond drillholes. During the production stage, samples are collected from blastholes. The last is more numerous but less precise. From a geostatistical view, this dissimilarity has to be considered to integrate the two sources of information. To combine this different data, three methodologies were investigated: simple kriging with local varying mean, cokriging and ordinary kriging. The exhaustive Walker Lake data set was used and it is considered the source to obtain the true grades. Initially, samples were obtained from the exhaustive data set at a regular spacing grid of 20 x 20 meters. Next, samples were obtained again from the exhaustive dataset at a regular spacing of 5 x 5 meters and a relative error of 25% was added. Then, both data were used to estimate blocks using the three methods mentioned. The grade tonnage curves were compared with the true block grade distribution. Moreover, the block misclassification was evaluated. The results showed that ordinary kriging produced estimates closer to the true block grade distribution and reduced the block misclassification.

Aug 8, 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 Alisson Paulo de Oliveira, Altair Lucio de Souza, Jacson Morais Borges, Cleiton Arlindo Martins

A customized version of the Microsim-PM software for one Steckel rolling mill was built and adapted for specific mill parameters. The focus of this study is to use this model, which predicts the austenite grain size distribution evolution during rolling, to understand and quantify metallurgical issues happening during hot rolling. This will allow the steel mill to optimize the rolling process and chemical composition before the first industrial trial. Materials rolled for final thicknesses of 4.75, 6.30 and 12.5 mm of a carbon manganese steel and a microalloyed steel were selected to tailor the equations used by the model and to accurately reproduce the reality of the Steckel mill. This paper analyses the results from the customized model and compares them to mill data and final microstructure. Measured and predicted Mean Flow Stress (MFS) values are compared. After rolling, the material is subjected to accelerated cooling using laminar cooling. These cooling curves obtained from mill data are also considered to analyze the final microstructure characterized for all the cases using EBSD. The quantification of the microstructure allows for a better understanding of the relationship between chemical composition, process parameters and mechanical properties.

Oct 1, 2019

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 Alberto Pesamosca

The paper presents the results obtained by the AC EAF supplied by Danieli at Kroman Çelik (Gebze-Turkey) after the planned upgrade to 150 ton. The EAF – 7,4 m diameter, based on the full platform standard design - is able to handle a maximum power of 114 MW and is equipped with the most advanced and reliable technology, including module injection system and the Hireg electrodes regulation system. Excellent results were already obtained with 120 heat size in terms of fast start-up and excellent performance figures. After the upgrade, productivity was increased up to 212 t/h, maintaining high process efficiency (365 kWh/t with 32,1 Nm3/t O2).

Jul 30, 2018

By Darina Manova

Plasma assisted surface modification methods have been used to nitride stainless steels in order to enhance hardness and therefore the lifetime of industrial components. Nevertheless, the corrosion resistance is not always preserved since it is very sensitive to the process parameters, either in implantation or in thermochemical diffusion techniques. AISI 316L stainless steel was plasma nitrided using three different techniques: Low Energy Ion Implantation (LEII), Plasma Immersion Implantation (PI3) and conventional DC pulsed plasma nitriding (DCPN). For each method several parameters were tested and some of them were selected to achieve the so called S phase of about 3 µm thickness and no nitrides precipitation. The nitrided layer was characterized with OM and SEM. Hardness was assessed on the surface with Vickers indenter and 25 g load. XRD was performed to characterize the S phase and to detect other phases if present and electrochemical corrosion tests were carried out in 3.5% NaCl solution. Although the S phase thickness in the three groups of samples was comparable, hardness was not and neither was the corrosion resistance. The PI3 samples were the hardest with the best performance in corrosion experiments, resulting in a higher breakdown potential and lower currents.

Aug 8, 2018

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

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 Detlef Ehlert

Flexibility in terms of producing high sophisticated products with an exceptional wide range of properties and dimensions requires physical based process models for the generation of optimal set points. Therefore SMS applies since many years an integrated PSC® (pass schedule model), PCFC® (profile, contour and flatness model) and CSC (cooling section control) for the use in hot strip mills, CSP® plants and plate mills offering best possible product tolerances. Focus during the development of the model was made on the best possible physical description of the rolling process to minimize the need of complex adaptation algorithms. As an addition SMS has also developed a microstructure model to ensure the quality control with respect to mechanical properties and to save up the needs of taking samples. Beside of this the modular design of the Microstructure and Material Property Model (MPM) offers additional benefits to improve the accuracy of the other models, e. g. the recrystallization model in the finishing mill. Using the results of that model strain hardening or softening effects during rolling can be predicted and an optimum pass schedule can be calculated to avoid rolling stability problems related to phase transformation.

Aug 16, 2017

By Dalila Chaves Sicupira

A pitting corrosion study of welded joints of lean duplex stainless steel (LDSS) UNS S32304 has been performed. LDSS S32304 thick plates were welded by different processes commonly employed in equipment and piping construction: SMAW (Shielded metal arc welding), GMAW (Gas metal arc welding) and FCAW (Flux cored arc welding). The electrochemical behavior of different weldment zones (fusion zone (FZ), base metal (BM) and heat affected zone (HAZ)) was characterized both independently using an electrochemical microcell and together through whole sample analysis. The electrochemical method applied was performed in acidified glycerin, a process fluid of the biodiesel industry. The results were correlated to the microstructural features of the materials. Based on the results, is possible to conclude that the breakdown potential (Eb) of the fusion zone (FZ) was higher than the Eb obtained for the heat affected zone (HAZ). In general, top samples show higher breakdown potential than root samples and also the samples welded using filler metal 2209 has a better anodic behavior than the filler metal 2307. According to the results, GMAW welding process with 2209 as filler metal was revealed as the optimum chosen for application of 2304 duplex stainless steels in this case.

Jan 16, 2018

By Sihai Jiao, Xiaoming Xia, Bo Yan

Checkered plate, which is also known as floor plate, has a raised pattern that provides excellent skid resistance for a wide range of applications, such as flooring, walkways, platforms, stair treads, covers, etc. As one of most common products, carbon steel checkered plate is used in low strength with a large thickness margin for corrosion and costs a lot in corrosion resistance treatment and maintenance. Although austenitic stainless steel checkered plate meets the requirements of general corrosion resistance, it is also hard to provide a highly comprehensive performance for its low yield strength, which mean higher thickness, higher weight, lower stability of structure. Combined the advantages of stainless steel and carbon structural steel, a roll-bonded clad checkered plate with high performance in skid resistance, high strength and corrosion resistant is developed. The metallography shows metallurgically bonded interfaces. Both external and internal bending at room temperature can be done successfully done without any cracks. The yield strength is also significantly improved. Therefore, roll-bonded clad checkered plate is superior in microstructure, strength, ductility and workability. An application case on a pulverized coal injection platform in an iron-making plant, is also introduced to show the way of processing and installation. After two years of installation on the platform, the product still keeps the original appearance. It implies that the developed plate could keep the facilities functions with much less or no maintenance and make them much safer.

Oct 1, 2019

By 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