Search Documents

By Kengo Usui

The energy consumption of Iron-making, especially Blast Furnace (BF), is very large. In order to maximize the utilization of limited resource, it is essential to reduce energy consumption and recovering waste energy in BF. This paper introduces energy saving equipment based on NSENGI’s over 80 BF construction experiences since 1963. The first is the technology for the Top Charging System for low fuel-rate operation. One of the important factors to achieve such operation, the burden should be charged uniformly. Since 1974, NSENGI have developed and delivered over 80 Top Charging equipments for such purpose and nowadays, developed new type Top Charging equipment with improvement of charging precision. The second is the technology for Solely BFG Operation in Hot Stove, which means no use of other fuel gas such as LDG, COG. It is realized by high combustibility of NSENGI’s Top-Combustion Hot Stove with Metallic Burners, and large amount of heat recovery of Waste gas Heat Recovery system with heat medium. The third is the technology for effective energy recovery in TRT. With NSENGI’s latest Gas Cleaning System “Multi-Vessel Electrostatic Precipitator" (MVEP), TRT will be able to generate higher electrical energy by approx. 30% than that of wet-type. In comparison with dry bag-type, MVEP allows temperature fluctuation which lead to generate higher electrical energy by approx. 10% NSENGI therefore, will be able to accept and meet your request widely.

Aug 1, 2018

By Breno Totti Maia

This work was a continuous and multidisciplinary development. Through studies of the blowing process and its parameters results, evolutions, improvements and adjustments were made on the lance’s hot face with Slagless® technology, as well in the process parameters and mitigating actions of the projection of materials out of the converter. The main results are the increase in the nozzle’s life with a “record mark” of 1785 heats, and water leakage occurrence in the cartridge decreased considerably reaching the mark of one year without any occurrence.

Oct 30, 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 Paulo Rodrigues dos Santos Junior, Luciano Passos de Jesus, Vagno Dordenoni Beltrame, Vinicius Antonio Ramos Pin

Faced with an increasingly demanding and selective market, a thorough analysis of each step of the processes is required in order to achieve high levels of performance. In addition to a major factor of importance in the rolling process, due to its high price, the rolls represent one of the main items in the cost of hot coils production. Using the 6 sigma methodology, there were opportunities for improvement in the grinding process, fatigue analysis, improvement in NDT in rolls, as well as means to guarantee operational stability, which allowed the reduction of roll’s consumption and consequently the cost of production.

Oct 11, 2019

By Manfred Hackl, Sergey Bragin, Alois Seilinger

The demand for hot rolled strip is growing in multiple ways. To remain competitive, new and existing mills must meet arisen challenges in the best possible way. The production of hot strip is a key element of steel production. Since close to half of all steel produced is hot-rolled to strip, mills require maximum throughput and availability combined with geometrical precision and the ability to create optimum material properties. Today there is a clear trend in developing new steel grades with high-strength and improved formability, like 3rd generation AHSS (Advanced High Strength Steels), as well as a trend to produce thinner and wider gauges. This trend challenges hot strip mills because it requires new technologies which provide more flexibility in metallurgical treatment during the rolling process. In order to meet and promote these trends Primetals Technologies is currently working on different concepts and solutions. One example is the development of a new mill stand technology Flex-HI HOT which allows to adapt the last finishing mill stands by efficiently switching from 4-high to a 6-high mode with small work roll diameter based on production needs. Another solution is to apply a permanent 6-high rolling stand at the end of the finishing train. A smaller work roll diameter allows to achieve higher specific thickness reductions and deformation rates resulting in significant thinner hot-strip gauges with valuable metallurgical benefits. The developed solution concepts with technological and metallurgical benefits will be presented in this paper.

Oct 1, 2019

By José Fagundes Junior, Cleudson dos Santos Rego, Bruno Bastos da Silva Murad, Vitor Borlot Borba

Since the startup in 2002, the Hot Strip Mill at ArcelorMittal Tubarão has increased gradually the coil output as the customers demand new and more resistant dimensionally challenging (thinner and/or wider) steel grades. As a critical feature for customer applications, improvements have been carried out aiming a higher thickness performance and reduction of internal losses while still meeting the more restrict tolerances booked by the customers. This paper presents the recent thickness performance evolution since 2017 and the main actions deployed to improve it.

Oct 1, 2019

By Jefferson Lisboa Lelis, Marcos Roberto Soares da Silva, Maiara Rodrigues Gouveia

Nowadays, due the development of new hot rolled strips at USIMINAS, established the necessity of realizing studies to define new parameters for the welding machine of new pickling line, in order to improve mechanical and metallurgical properties of these materials. The aim of this study was to evaluate the weldability of high strength low-alloy steel with low boron content with tensile strength above 600MPa.The influence of energy input and preheating temperature on the mechanical properties of hot rolled strips were analyzed at three distinct thickness (2, 4 and 6 mm). To perform these evaluations were used tensile test, micro-hardness, metallography (micro and macro examination) and scanning electron microscopy analysis. In resume, a good welding performance was achieved, increasing preheating temperature and the welding energy higher than 60%.

Oct 13, 2019

By Gerhard Finstermann, Ichiro Maeno, Takehiko Saito, Hironori Shimogama, Konrad Krimpelstätter

Automobile manufacturers are developing Electrified Vehicles with light steel body structure designs that reduce mass and therefore greenhouse gas emissions over the vehicle’s entire life cycle. This raises the demand for the production and development of Advanced and Ultra High-Strength Steels (AHSS / UHSS) and Electrical Steels with increased permeability and reduced core loss to improve energy conversion efficiency. To meet this requirements the steel market is tending towards new generations of AHSS with improved formability (3rd generation AHSS) and high-silicon steels with higher strength and thinner products. With this growing demand for advanced high-strength steels and electrical steels, producers are faced with a unique and interesting challenge in producing materials that strain or exceed the capabilities of existing mill equipment and automation designed to produce low- to medium-carbon sheet. While specialty steel producers have known for decades how to process special high-strength steels and thinner gauges, this equipment typically does not offer the yield and productivity desired by the market, necessitating innovation in re-engineering existing equipment to meet the market demands more economically than new construction. In the case of cold rolling, this can be supported through variable roll geometries, more effective roll-gap lubrication technologies, application of strip heaters (Warm Rolling) to reduce risk for edge crack propagation and strip breaks as well as continuous rolling managed by state-of-the-art automation technologies.

Oct 1, 2019

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

By Pedro Cunha Alves, Wagner Viana Bielefeldt, Vinicius Cardoso da Rocha, Augusto Lachini Pereira, Julio Aníbal Morales Pereira

The capacity of steelmaking slags (CaO-SiO2-Al2O3-MgO) on inclusion removal from liquid steel was investigated through experimental conditions. Laboratory experiments with slag and steel samples (with inclusion population known) were performed using a vertical electric resistance furnace at 1600 ºC. After the melting experiments, slag and steel samples were separated and analyzed regarding their chemical composition and inclusion population evolution. The capacity of slags on inclusion removal was evaluated based on the thermodynamics (solid and liquid phases proportion, phase composition and effective viscosity of slags) calculated using the FactSageTM 7.2. Results indicated that changes in the composition of slags (regarding CaO/SiO2 e Al2O3) presented effects on the steel cleanliness. The total inclusion density decreased in all steel samples and the removal of inclusions by slags shows a tendency to improve as their viscosity decreases (< 0.23 Pa.s).

Oct 1, 2019

By Stefano Baf

This paper describes the main technical and process solutions applied to the extrathick and wide slab caster built at Yingkou (Liaoning, P.R. of China), as well as all the features required to achieve the surface and internal quality targets.

Aug 16, 2017

By Elham Kordzadeh

As the world’s reserves of coarse and high-grade iron ores continue to shrink, beneficiation is becoming increasingly important. The resulting concentrates cannot be used directly as feedstock for iron making, but require an additional agglomeration step. Pelletizing is preferred, because the uniform chemical, physical, and metallurgical characteristics of pellets make them a more desirable feed for the iron making processes. The heat hardening or induration of pellets is typically done in shaft furnaces, grate-kiln systems or on straight grates. Rotary kilns were originally developed in the late 19th century for Portland cement production [1]. The main development work for the successful adaptation of the process to the thermal treatment (induration) of green balls from iron ore was performed by Allis Chalmers in Milwaukee, Wisconsin, USA in the 1960’s [2].The straight grate process, which was first used in 1955 at Silver Bay, Minnesota, was a dedicated development with the aim to pelletize and indurate magnetite (taconite) concentrate [2]. There are various important technical and economical distinctions between the two pelletizing technologies. The most important differences include that a grate-kiln has three distinct pieces of equipment, a preheat grate, a rotary kiln and an annular cooler, whereas in the case of a straight grate, the entire indurating process is done on one piece of equipment only. In addition, both technological solutions have differences in their recuperation systems, direction of air flow in drying, number of burners, form of pellet movement, etc., which cause differences in raw material suitability, process control, economical aspects, plant operation and product pellet quality.

Oct 30, 2017

By Giuseppe Pintaude

This study aims to evaluate the effect of specimen preparation on the dry sliding wear behavior of CA-6 NM stainless steel. Two different surface finishing manufacturing processes were applied: lapping and metallographic polishing. The wear tests were conducted in reciprocating ball-on-flat system, performed for two loads: 5 or 8 N. For all test conditions, hardmetal ball was employed as counterbody. The surfaces were evaluated using 3D interferometry technique to determine their surface roughness, including texture analysis regarding isotropy. Surface characterization results indicated the presence of texturing and preferential orientation, since the parameter Str was smaller than 0.5 for samples of both the studied conditions. Two distinct levels of isotropy evaluated through Str parameter were achieved: 0.13 for lapping and 0.3 for metallographic polishing process. It is clear from wear tests that the variation of average surface roughness is the key point for tribological behavior of CA-6 NM stainless steel.

Jul 31, 2018

By Giuseppe Pintaude

The use of two-dimensional shape parameters to characterize abrasive particles is a possible approach to express their angularity. Nonetheless, in sliding abrasion, especially in pin abrasion testing, coated papers structure plays an important role and even its damage during the wear process should not be neglected. This manuscript discuss the limitations of two-dimensional shape descriptors in distinguishing wear caused by relatively hard particles, indicating that the wear data obtained in sliding abrasion tests are unable to distinguish different types of coated papers used when only the two-dimensional particle projection is considered for shape characterization.

Jul 31, 2018

By Jean Viana Bahia, Antônio Adel dos Santos, Vicente Tadeu Lopes Buono

During cold rolling of Cr-Mo alloyed DP steel, considerable oscillation of thickness may occur. The literature points out that such occurrence is due to non-uniform cooling of the coil after the hot rolling process. Since the austenite transformation in this steel continues after coiling, the microstructure and, consequently, mechanical properties are very susceptible to natural variations in cooling rates associated with distinct positions of the coil. The influence of coil cooling conditions on thickness oscillation during cold rolling was evaluated in this work by using both industrial experiments and dilatometer tests. It was verified that an industrial coil presented large variation of mechanical properties associated with its heterogeneous microstructure. Consequently, thickness oscillation occurred during cold rolling. Dilatometer tests simulating hot run-out table and coil cooling showed that the austenite transformation is very slow under small cooling rates that occur after coiling. Thus, the slow transformation rate makes the coil very susceptible to environmental conditions around it during its natural cooling and is responsible for variation in mechanical properties of the coil. To ensure the formation of a more homogeneous microstructure in the whole coil, it is necessary either to make use of technologies that improves the cooling uniformity or to adjust the steel alloy design. The latter alternative has been done with relative success by using conceptions with lower amounts of Cr and Mo.

Oct 1, 2019

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 Camilo dos Reis, Edmilson Fernandes Dadomi, Claudio Silva de Paulo

In the hot strip mill production, one of the factors that may affect the productivity is the occurrence of failure due to the geometry of the strip at the exit of the rolling mill, because the tip of the strip can turn-down or turn-up. This study had the objective of evaluating the behavior of the strip when leaving the working rolls, through numerical simulation, aiming to know the influences of the main variables that govern the formation of the turn-down. The methodology consisted in performing the computational simulation of the strip mill and to vary the operational and geometric parameters that could influence the process. The results showed that the rolling of hot strips of HSLA material with final thickness varying between of 3 to 6 mm and a reduction of 6.6% to 11.0% in the last stand of a hot strip mill, tends to bend towards the roll with larger diameter, higher friction coefficient , higher temperature and lower limit of material flow. It was observed that the variation in diameter is the main factor that contributes to the formation of the curvature of the front-end of strip. Based on these results, several measures were implemented in the industrial line, with a significant reduction in the occurrence of turn-down.

Oct 2, 2019

By Emanuele Osto

In late 2013, the installation of the world's first application of a break-through technology for rail hardening was started at Baogang Iron & Steel (Group) Co. Ltd. in Inner Mongolia, China, one of world's leading rail producers. The "Injector Dualphase Rail Hardening" (idRHa+) system was developed by Primetals Technologies and Centro Sviluppo Materiali S.p.A. (RINA-CSM) a Technical Center headquartered in Rome, Italy. Baogang was a key partner, providing its large expertise of premiumrail producer, including its experience with existing offline technologies. With a design based on thermal, mechanical and metallurgical models, idRHa+ can apply customized cooling protocols, so to obtain the desired microstructure and hardness distribution across the rail head, with a high degree of accurateness and operation flexibility. idRHa+ can be installed in inline or offline configurations. During 2014, the system was successfully commissioned at rail mill #2 in the city of Baotou, Inner Mongolia, and entered the regular commercial production. This paper gives an overview of the key concepts behind idRHa+'s design, the progression of its commissioning and testing till the ramp-up to consistent industrial operation. Derived from idRHa+ research and experience, other water-cooling technologies are available for different applications such as: quenching & tempering of medium-large sections, control of distorsion of merchant bars, quenching of stainless grades for improving the resistance to corrosion.

Aug 16, 2017

By Božidar Šarler, Umut Hanoglu

A rolling simulation system has been developed to calculate the macroscopic rate of deformation, stress, strain, and temperature fields by using a novel meshless method. The model is based on two-dimensional traveling slice assumption. The slices are aligned towards the rolling direction. The initial size of the billet, bloom or slab and the geometry of the grooves at each rolling stand, the distances between the rolling stands, and continuous or reverse rolling can be arbitrarily considered. The purpose of this paper is to complement these development by predicting and visualizing also the grain size of steel over the strand cross-section for each position in the rolling mill. The grain size models have been in one-way coupled to the macroscopic calculations. First the critical strain for dynamic recrystallization is being checked. If the calculated strain is higher than that, considering also the time for meta-dynamic recrystallization, dynamic or meta-dynamic grain size calculations are carried out. If the strain is too low then only the static recrystallization is considered together with its required time. Finally, austenite grain size and ferrite grain size are calculated respectively as the steel cools down. The listed physical models are based on collection of empirical relations found in literature. The user of the system is free to choose or create the model he wants with his own parameters. The simulation system has been coded as a user friendly computer application for an industrial use based on C# and .NET framework and runs on regular PCs. The computational time for a rolling simulation is usually less than one hour and can thus be straightforwardly used for optimization of the rolling mill design in a reasonable time.

Oct 1, 2019

By Antonio Esposito

Saving energy and reducing pollution by minimizing emissions are today great challenges in the coking industry worldwide. In order to achieve satisfying results, equipment as well as technology should be continuously improved and updated. The most modern design tools should be adopted to maximize the coke production rate also ensuring the best coke quality. In this scenario, Paul Wurth is realizing the new coke making plant of CSPecem, Ceara - Brazil. These batteries are based on Paul Wurth “jumbo oven concept”. This solution incorporates all most modern features and design upgrading, in the aim of an easy and long-lasting operation putting a particular attention to environmental performances: the reduced number of ovens and the low number of pushing per day have the main effect of reducing pollution sources. Finally the paper will highlight Paul Wurth SOPRECO® System, which is foreseen to be installed in CSPecem batteries. SOPRECO®, which is capable of controlling the pressure for each individual oven in a coke oven battery, is thus able to reduce volatile emissions through doors, roofs and stand pipes up to 90%. The coke oven gas (COG) produced during the carbonization process is cleaned in a coke oven gas treatment plant to the level stipulated by applying the Best Available Technology (BAT).

Aug 1, 2018