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By Francesco Toschi

The Special Bar Quality family comprises a wide range of steel grades, mainly requested by the automotive, energy and engineering sectors, for applications where significant performances are required (eg. stresses, temperatures, working cycles, etc.). To meet these requirements it is necessary to reach a precise control of both the mechanical characteristics and metallurgy structures along the whole production chain. For semi-product with large dimensions, such as equivalent diameters around 300 mm, this is traditionally obtained through a manufacturing route which comprises the casting in ingots followed by reheating, forging and rolling. After 2010, new processes were investigated and technologies developed to replace the ingot route with a continuous casting followed by controlled high-reduction rolling. In these processes a seamless integration of CCM with rolling is implemented so to obtain the precise control of material flow, applied deformation and working temperatures. By using the proper combination of rolling diameter, speed and applied reduction, a very good control of the metallurgy structure across the whole section can be obtained, so to also remove the internal discontinuities ("voids") generated during the continuous casting. These processes, which can be defined "forging-like", are applicable to several grades also with large semi-product dimensions (300 mm and more). Besides, removing the ingot route means increased yield and productivity, which is very beneficial to the economical management of the plant. An example of this "forging-like" process is represented by the high-reduction blooming stand installed by Acciaierie Venete in the Padova-Camin mill. This article describes its main concepts as well as its technology and process features.

Oct 30, 2017

By Kelen Juliane Mucelin

In order to better understand the tribological behavior of self-lubricating materials, Fe-Si-C matrix composites containing solid lubricants added during the mixing step were studied. The samples were produced by conventional powder metallurgy route, presenting total contents of 5%, 7.5% and 10% in volume of h-BN and graphite mixtures as solid lubricants. The composites were evaluated in terms of tribological properties, under reciprocating sliding conditions, and mechanical properties by using tensile tests. Additionally, the wear scars were characterized by Raman spectroscopy and scanning electronic microscopy. Higher total contents of solid lubricants greatly increased scuffing resistance however decreased mechanical properties. Furthermore, increasing h-BN contents reduces both properties. These results confirmed the applicability of such sintered composites as self-lubricating parts, reaching values up to 7000 N.m for scuffing resistance combined with ultimate tensile strength of 220 MPa.

Jul 31, 2018

By Hongshuang Di, Tianyu Zhang, Huiqiang Huang

A CMnSiAl transformation induced plasticity (TRIP) steel was used to study the effect of retained austenite on room-temperature mechanical properties. The steel plates with retained austenite were obtained by hot rolling, cold rolling and subsequent continuous annealing. The starting and finishing temperature of hot rolling are between Ac1 and Ac3. Reduction ratio of cold rolling is 75%. The continuous annealing is carried out at different intercritical temperatures. The relationship between work hardening exponent and retained austenite was discussed. The results show that, the Ac1 and Ac3 were much high because of the alloy elements, and the temperature range between them was wide. Due to the high hot rolling temperature, the grains was hereditarily refined as a result of dynamic recrystallization. Annealing at intercritical temperature of 930 ºC, retained austenite with relatively high stability reached a maximum volume fraction of 25%, a maximum total elongation of 30.2% and a best ultimate tensile strength × total elongation of 20.1 GPa·%. Instantaneous work hardening exponent reflects strengthening mechanisms at different strain stages. The TRIP effect of retained austenite is the main mechanism during deformation. With retained austenite of sufficient amount and high stability, continuous work hardening was observed in the tensile specimen of 930 ºC.

Oct 1, 2019

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 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 Luca Tommasi

Danieli complemented its wide range of production plants for the iron and steel industry with a further step upstream into iron ore pelletizing and beneficiation. Danieli has engineered and constructed a state of the art and fully automated pilot plant facility – pot grate and sinter box – at Altos Hornos de Mexico S.A. (AHMSA) Pelletizing Plant, Monclova, Mexico. Installation and commissioning were completed in October 2009. Key features of the pot grate include the avoidance of the need for operator intervention during the test, automatic system preheat, absence of dead time, heat recuperation system with an air/air heat exchanger, oxygen control in preheating and firing with zirconia oxygen analyzer, possibility to test deep beds up to 625 mm. A series of projects have been accomplished by AHMSA availing of the pot grate facility with the aim to enhance pellet plant productivity and to reduce operating costs. The results obtained by use of Danieli pot grate combined with the experience and skill of plant operators has shown significant technical and economical benefits thus fully justifying the initial investment made by AHMSA and confirming the importance of having an in-house testing facility in order to optimize industrial plant operations.

Aug 16, 2017

By Andrea Zanon

Slitting processes have been used for many years to increase the productivity of smaller diameter deformed bars, without making major investments in the rolling mill. This technology is used mainly for the production of reinforcing bars (7-20 mm diameter), but successful applications exist also for round bar production. The multi-slitting process enables to produce up to 5 bars starting from one billet, thus increasing the productivity of the smaller products. Danieli Morgårdshammar, world leader in the supply of rolling mills for long products, has been a front-runner in slitting technology since its first applications and has recently developed, first in the world, the technology to produce 5X8mm rebar. This process has been recently applied in BRSM steel, a company based in Bangladesh which is a worldwide benchmark for slitting technology performances. This paper presents the necessary modifications which need to be considered when developing a 5-strand slitting project (and multi-strand slitting projects in general), as well as the results obtained at BSRM Steel when the process was implemented in 2016, the first rolling mill in the world rolling 5X8 mm slit rebars.

Oct 30, 2017

By Richard Harvey, Robert Paul Mawer

In recent times there has been an increase in the demand from Steel plants for a technology that offers the most economical environmentally sustainable solution. In terms of blast furnace off gas cleaning this has seen a drive towards Cyclone technology replacing the older Dustcatchers. Cyclone technology can achieve dust removal efficiencies as high as 95% increasing the dust yield at the primary stage of gas cleaning. The dry dust (rich in Fe and C) can then be recycled to the Sinter Plant or Blast Furnace. Capture of dust at this stage also has the benefit that sludge generation from the secondary stage is also reduced meaning less waste to landfill and / or recovery of some of the by-products for further use. Primetals Technologies already offer a state of the art Tri-Axial Cyclone installed on many sites world-wide, however, this paper focuses on a hybrid of this technology, the DustClone. The DustClone is a low CAPEX unit that is essentially a Cyclone housed inside the Dustcatcher. This unit is aimed at operators who may be carrying out smaller scaled shutdowns / repairs that normally have a reduced CAPEX. This paper describes the technology that Primetals Technologies have developed.

Oct 1, 2019

By Alessandro Molinari

In recent times, coke oven machines are acquiring a more prominent role in the coke making process. Apart from the traditional handling of the coal and coke flow, nowadays these machines are also deeply involved in all environmental and process control aspects. Paul Wurth coke oven machines have been developed by Schalke to meet the most recent requirements in terms of emissions control, automation, instrumentation, operability and maintainability. In CSP, Ceará, the new coke making plant represents the status of the art of the technologies applied to the whole coking process; starting from the Coke Oven Batteries and the Gas Treatment Plant developed by Paul Wurth up to the Coke Machines supplied by Schalker Eisenhütte, whose technology is now part of Paul Wurth coke making products portfolio. Present paper describes the plant configuration focusing on Coke Oven Machines and the key factors which are guarantying the success of the project.

Aug 16, 2017

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 Daniel Stickel

Current political, economic and ecological guidelines demand the increase of power densities of nearly all machinery parts today. In order to further lower the wear rate towards the ultra-mild sliding wear regime an integral approach is needed, which has to regard contact conditions, surface topography, surface chemistry, as well as sub-surface properties. Still there are no simple parameters to classify the performance of tribosystem. In this study the area and volume affected by tribocontacts are calculated by means of a three dimensional elastic-ideal plastic contact model. The surfaces are generated by means of conventional machining procedures and characterized by scanning white light interferometry. The further input data as to normal and friction forces are derived by ultra-mild sliding wear tests under boundary lubrication conditions of carburized steel against carburized steel and 52100 steel against case-hardened spheroidal cast iron. This contribution will depict the distinct influence of the topography on friction and ultra-mild sliding wear of common Fe-base materials and point on the marked importance of highly localized effects, which govern the acting mechanisms.

Jul 31, 2018

By Wolfgang Kern

The implementation of the Gas Treatment Plant (GTP) for CSPECEM, Ceara-Brazil is a result of the closed partnership between Paul Wurth Italia S.p.A. and DMT, the German leading company in Coke Oven Gas Treatment Plants. In addition to technical issues reducing emissions, avoiding of waste and saving environment and energy were technical challenges during the engineering phase. Below mentioned three descriptions of technical solutions represents examples of a number other innovations based on DMT’s know-how and experience in the field of by-product plants. Generally the design of the complete GTP is based on the consideration of modern features and design upgrading, with the aim of a safe operation with stable conditions and a long-living cycle of the whole of the plant.

Aug 16, 2017

By Leonardo Araújo Peruch, José Fagundes, Henrique Carneiro Pinto, Marco Túlio Costa, Nayara Coutinho, José Fabiano Martins Assunção

The objective of this project was to increase the hot charge by reducing reheating energy consumption and raising the productivity of ArceloMittal Tubarão's hot strip mill by changing the HSM’s schedule process with optimization of the relocation process of slabs after HSM’s chance with focus on slab temperature in reheating time. The project began with the revision of metallurgical rules for the relocation of materials, definition of criteria temperature setting (hot / cold), definition of restrictions of the process and review of modus operandi scheduling process. With the implementation of the process / system it is expected to achieve a 10% increase in the hot charge index in slabs reheating furnaces and increase productivity of the ArcelorMittal Tubarão hot strip mill

Oct 3, 2019

By Rogério Martins Pereira, Charles Pierri de Souza, Lucas Gabriel Correa

The Tandem Cold Mill is composed by stands with rolls positioned so that the rolling force can be transmitted to the strip being processed. Due to the mechanical stresses inherent in the process, the roll bearings are heated and are equipped with lubrication and cooling systems. Nevertheless, there is the challenge of continuously monitoring the temperature of the bearings, which would allow preventive intervention in case of overheating. This paper presents an in-house solution to temperature measuring system applied to the backup roll bearings of a continuous Tandem Cold Mill. The system uses Zigbee technology and is integrated with the main control system, allowing early diagnosis of bearing heating and proper intervention. Results and features of the system are discussed.

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 Roman Vaynshteyn

In places where Blast Furnaces are usually located, climatic factors may be unfavorable. Raw materials may be exposed to e.g. rain during transport/storage, bringing moisture into the process with consequences for stability and hot metal cost. This paper describes a technology for drying and pre-heating pellets and coke in the stockhouse. It does not require additional handling or logistical equipment and does not introduce extra transfer steps and degradation. Not only can moisture content be reduced, it can be controlled to a stable level by the operator.

Aug 16, 2017

By Jovanir Francisqueto, José Fagundes, Nayara Neves Coutinho, Marco Túlio Costa

The purpose of this project is to increase the visibility of which will be daily produced on the hot strip mill (HSM). The forecast was performed through the implementation of an automated tool for weekly HSM production planning. The project was started with the definition of the weekly planning process, through the determination of the main business objectives, like as: priorities of service (customers and delivery date), definition of HSM’s rules and restrictions of operating resources. Using a sophisticated mathematical model, through the computational simulation is possible the experimentation of various production scenarios, allowing the visualization of volumes by type of sequence, clients / priorities, mix to be produced, cylinder change quantity forecast, better forecasting of the productivity of the HSM, consumption of utilities, within others. Main benefits: sequencing which production orders should be produced, reducing unforeseen stops due lack of material, improving the quality of the stock which allows the reduction of the aging of slabs in the slabyard and the vision of customer services. Computational simulation as a weekly planning tool achieve, with other benefits, to present alternatives for better decision making.

Oct 6, 2019

By Álvaro Lúcio

This paper outlines the DPC process as na economic and environment friendly option for the use of cultivated forest as a source of raw material for metallurgical charcoal.The DPC process was specially developed to bring logistic, environmental, technical, economic and global energy efficiency when compared to termal1 the existing biomass carbonization process. The DPC process utilizes the volatile materials (condensable and non condensable) as a source of the energy required by the carbonization process guarantying its complete combustion. As result the DPC process avoids the burning of termal1 the loaded wood, obtaining a higher charcoal to biomass yield, and avoids the emission to the atmosphere of polluting gases. Gases emitted by the carbonizing wood have na energy termal1e enough to dry the wood soon after its harvesting. By avoiding the storage in the field during na average of 150 days, the resulting economy is quite significant. As a termal1e1 the higher charcoal to biomass yield na termal1e1e economy is obtained through the reduction of the cultivated forest term. This paper emphasizes the economic advantages of the DPC process.

Aug 16, 2017

By Sara Hornby

After almost half a century of experience in using DRI/HBI in electric arc furnaces (EAFs), and taking into account the decrease of natural gas cost in the USA, it is interesting to revisit some trends and controversial issues around this alternative iron source. This paper reviews aspects like the evolution of iron ore quality and its influence on EAF operation; DRI stockpiling and transport, regarding the risk for selfcombustion; optimum charge design; cold DRI/HBI charging (fifth hole, bucket, transporter); hot charging (ways and results); carbon content, metallization and silica in DRI/HBI, and its influence on EAF operation and performance; oxygen / carbon balance; chemical energy and DRI/HBI charge.

Aug 16, 2017

By Daniel Hajduk

Efficiency of back up rolls depends mostly on two parameters – length of campaign and dressing amount after the campaign. The longer the campaign (in terms of rolled tones) is, the higher the dressing amount. To solve this task properly it is necessary to know the distribution of accumulated damage in the working layer of the roll caused by previous campaigns and by loads (separating force and bending) during present campaign respecting changing conditions of material properties (hardness) through radius of the roll. To find an optimum dressing amount an algorithm has been developed and specialized computer program will be presented, that takes real measured loads during the backup roll campaign, calculates fatigue damage in the roll and suggests relevant dressing amount. This can help to prolong service life of rolls, minimize the risk of spalls and reach maximum efficiency in terms of rolled tones/km per roll.

Jul 30, 2018