Search Documents

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 Gabriel Oliveira Glória

Due to growing concern about the ambient impacts, lignocellulosic fibers are been investigated to replace the synthetic ones in polymer composites The giant bamboo fiber, a relatively unknown lignocellulosic fiber with potential for composite reinforcement, still needs to characterize for possible engineer applications. However the giant bamboo fiber has low adhesion with the polymeric matrix. In order to understand the interaction that occurs between the bamboo fiber and the polymer matrix is necessary to evaluate its physical and chemical characteristics. Therefore, the present work analyzed the giant bamboo fiber by means of Fourier Transform Infrared (FTIR) spectroscopy. The spectrum revealed main absorption bands typical of giant bamboo fiber specific molecular interactions.

Aug 16, 2017

By Dyego Monteiro de Souza

This study compares the wear resistance of specimens lubricated with biofluids or mineral oil. Tribological studies were performed by ball-cratering test. In these tests were used as lubricants epoxidized soybean oil, castor oil and mineral oil. The specimens used were untreated and nitrided AISI 4140, while a steel ball AISI 52100 was used as a counterbody. In order to analyze the results obtained, the worn volume was calculated and the characterization of the crater, after the test, was made using optical microscopy and SEM. Wettability was also measured for the different surface condition and lubricants. As expected both specimens showed a smaller volume worn when lubricated with mineral oil due to inherent properties of this type of lubricant. Among the vegetable oils studied, the castor oil showed a better performance in the lubrication of the specimens untreated while on the nitrided specimen have shown less wear when lubricated with epoxidized soybean oil, indicating a difference in the efficiency of oils, as lubricants, depending on the surface conditions of the mechanical components.

Jul 31, 2018

By Davide Onesti

Electrode regulation is the technology at the heart of the AC and DC Electric Arc Furnace. As such, in the last decade it underwent continuous improvement to maximize the EAF performances, in terms of process efficiency, machine utilization and operator safety. Given this background, Danieli Automation’s efforts in the field of electrode regulation have been focused on fast response to scrap cave-in, compensation of supply variations, automatic resonance detection, transformer protection, dynamic regulation of the electrical and chemical set-points, coordination and control of slagging and foaming agents, arc irradiance supervision. An extensive analysis of operator utilization and feedback was also carried out to develop an innovative system HMI. In this field, the choice of the variables shown to the user is the key aspect to allow a prompt process evaluation by the operator, who can refer to a condensed set of useful data. This paper will describe the innovative features and embedded models of the electrode regulation module (Q-REG+) and the supervision HMI, together with the effects of their application on EAF process efficiency and system usability.

Oct 30, 2017

By Sébastien Gérardin

Developed for more than 30 years, continuously improved, cored wire is nowadays a reliable solution for the improvement of sustainability, safety, health and doing quality and cost saving. Cored wire allows the addition of ferroalloys and treatment of liquid steel, especially concerning the calcium treatment. Amongst all the processes in secondary metallurgy, calcium treatment is certainly the most critical one before casting. Besides the traditional CaSi and CaFe wires, new types of wire have been designed for becoming the new reference in calcium treatment. PapCal (calcium insulated wire) and HDx (high density calcium wire) are a very versatile range of products. Indeed, according to the steelmaking process parameters (steel grade, treatment temperature, ladle size, calcium content targeted in tundish and even injection conditions), their technical specifications may be adapted in order to optimize the calcium treatment as high as possible.

Aug 16, 2017

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 Francois Mignard

With a limited global steel production growth, automotive application market shows interesting volumes and trends especially in emerging countries. The recent period has again enabled Siemens VAI to confirm a position amongst leading suppliers of new plants serving high-end steel production in particular for unexposed and exposed automotive material. With a series of recent plant references in operation and under construction, relevant answers to such sustained level of performances are highlighted along the downstream processes. Designed for a wide range of applications, Siemens VAI processing lines includes advanced technological and state-of–the art equipment, among them, Solid state laser welder, Pickling Tunnel tanks, Skin pass mill and Tension leveller, Side trimmer with dynamic width adjustment, and new generation of Automatic surface inspection systems. With a continuous aim of driving improvements, Siemens VAI has also developed Global Quality Monitoring solutions notably through advanced software which provide just-in-time warnings and assist steel makers in the daily operation of their lines. As lifecycle partner, Siemens VAI offers solutions and services in metallurgical expertise from metallurgical modelling, through physical simulation on rolling, annealing and galvanizing processes, and enables Siemens to accompany our customers along with their project definition till fulfilment of highest market requirements.

Jul 30, 2018

By Norbert Asamer, Stefan Purrer

Depending on the product or the material grade, conventional deburring machines, such as e.g. with rotating hammers, are in many cases not capable to reliably or completely remove burrs from the edges of a continuously cast product. Burr, however, is generated at the front and/or tail ends of a slab, bloom or billet as a result from torch cutting. Likewise, traversal grinding of the slab’s rolling surfaces can also cause burr at the long side edges of the slab whereby such burr can even be more difficult to remove. Based on their experience and know-how with abrasive machining processes (abrasive cutting, high-pressure grinding) over a period of more than 50 years up to now, BRAUN has developed a highly flexible deburring grinding machine for applications which are too difficult for conventional deburring techniques. BRAUN’s deburring grinding machines were successfully introduced to the steel industry and have proven their worth under normal production conditions already. The subject paper describes the key features and advantages of BRAUN’s machine design and the operational results from the first already completed projects.

Oct 1, 2019

By Enrique Francisco Somolinos Garcia-Morales

In this paper we will discuss the benefits of a very innovative way of introducing MgO in the blast furnace operation through the sinter, using mini lumps of dunite. By changing the traditional way of using an MgO bearing material in fines form (particle smaller than 5 mm), most of the MgO inserted material behaves as inert during the sintering process, with the effect of having the following parameters (among others) improved: productivity at the sintering bed, permeability inside the blast furnace, energy consumption, stability of the operation.

Aug 1, 2018

By Carlos Martins de Oliveira

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

Aug 8, 2018

By 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 Piezanowski Ludivine

With the aim to reduce the hot metal production cost, ArcelorMittal Gent decided to integrate more ores with finer particle size distribution in the raw material mix for the production of blast furnace sinter. As a consequence of such an increase of finer material in the sinter raw mix, the sinter machine productivity and the quality of the sinter are affected. In order to compensate this impact, modern granulation technology can be employed. Within this context, ArcelorMittal Gent has invested in a vertical intensive mixer. The equipment was placed before the existing drums, with a function of “mixer”, whereas the drums are fully optimised for the nodulizing process. The paper presents the results of the industrial operation during the commissioning phase of the new equipment. Gradually increasing the proportion of fine material in the sinter raw mix has made it possible to compare the performances of the old system using drums for mixing and pelletizing with the new system using an intensive mixer combined with a nodulizing.

Aug 1, 2018

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 Wan-sub Kim, Joon-Tae Lee, Seongkyu See, Yong-Kyu Park

Softening heat treatment of CHQ alloy steel (Cr-Mo Steel) is a bottleneck process that requires 90% or more of the entire manufacturing process. In order to reduce the property deviation between edge and center and remove the low-temperature structure problems, CHQ products is heat treated by customers. This technology comes from the idea to solve the problem by applying the concept of “In-line isothermal transformation through initial quenching + heat source addition. Consider the stability of field operations, durability from high ambient temperature and fall of scale, Instantaneous heating and cooling control was required for the conversion of slow cooling and rapid cooling products. An electric heating system was applied to the underside of Stelmor air-cooling nozzle. Using the Scan Pyrometer, the feedback control was performed and fine temperature control was performed through the thermocouple by zone. Through the this technology, it is possible to develop and expand products that can be shortened or omitted by the heat treatment process of customers.

Oct 1, 2019

By Antônio Aldenor Pinheiro Neto, Matheus de Lima Vieira

In mid-2015 the steel industry faced a strong crisis due to the weak performance of the Brazilian economy and the persistent entry of Chinese steel into Brazilian territory. This situation demanded that Brazilian steelmakers seek to develop products to meet new export markets. within the volume of exports possible are the rebars, where its applications are in the construction industry. One of the largest importers is Peru which has a large percentage of this export volume. This market demands as a priority requirement the surface quality of blue condition (low oxidation index) and mechanical properties normative.in order to meet the items required by the customer at a competitive cost, a vanadium microalloyed steel was applied to the hot rolling process without heat treatment after the last rolling pass. Where the great challenge was to achieve a high level of stretching without compromising the minimum limits of tensile strength. Assuming that the steel used is the correct one interventions were made on rolling parameters such as set-point temperature, residence time of pieces in the furnace, linear mass and rolling speed. All the changes made were based on statistical tools and practical tests. Finally, with the execution of actions generated from the statistical analyzes and tests it was possible to reduce process losses by 96%.

Oct 1, 2019

By Jerin Russell

This paper presents a new instrument for real-time detection of excessively coarse material in the overflow pipes of individual hydrocyclones using a non-invasive acoustic measurement technique. The hydrocyclone is an important device used in mineral processing beneficiation circuits for classification of mineral slurries by particle size. It separates a single input stream into two output streams; an underflow of coarse particles that undergo additional grinding for further size reduction, and an overflow stream of finer particles that typically goes directly into a flotation circuit for recovery of the desired mineral. However the hydrocyclone is a major piece of equipment in the beneficiation process that has no instrumentation for directly measuring its performance. The parameters currently measured – inlet pressure, feed flow rate, feed flow density – are common to the entire hydrocyclone cluster which typically has three to twelve hydrocyclones. Thus no information is available to detect individual hydrocyclones that are operating poorly. The system described in this paper detects the presence of unwanted excessively coarse material in the overflow stream of a hydrocyclone using sensors mounted to the exterior pipe surface. It provides real-time monitoring, trending and alarming of the coarse material level. This enables operators to identify poorly performing hydrocyclones, and enables corrective action to reduce or eliminate the coarse material discharge. Improving the classification efficiency of individual hydrocyclones will improve the overall classification efficiency of a hydrocyclone cluster. This leads to less variation in the particle size distribution and slurry density in the flotation feed, which will in turn improve overall mineral recovery. The reduction of unwanted coarse material in the flotation feed reduces the accumulation of that material in flotation cells. This can lead to equipment damage, and unplanned shutdowns due to events such as blocked dart valves.

Aug 16, 2017

By Patrick Edward Connell

The next generation of the well-established 3-roll Reducing & Sizing Block (RSB), the RSB SCS® is the latest milestone in reducing and sizing technology for SBQ products. It offers enhanced bar quality, improved productivity, mill availability and economy as well as a simplified, safe and environmentally friendly operation. A newly developed modular drive concept of the RSB SCS® grants a smaller footprint in the layout, a reduced oil-lubrication volume and a simplified maintenance schedule. Intelligent engineering leads furthermore to reduced hydraulic functions of the RSB SCS®, which ensures a safe and environmentally friendly rolling. Another integral part of the RSB SCS® is an innovative stand changing concept, which allows automatic stand changing within three minutes. The new RSB SCS® also includes a Fast Remote Control (FRC) which enables the immediate adjustment of the roll gap against the rolling force (under load) within milliseconds. Size changes along the free-size range can also be made within the traditional billet gaps in less than five seconds. At the core of the future-oriented RSB SCS® is a real-time closed-loop control system called Size Control System (SCS®) acting with 3-roll stands adjustable under load (AUL) and / or the heavy duty stands. These features remarkably further improve the rolled tolerances and their reproducibility, and at the same time simplify the operation by means of an automated optimization of the process parameters for the rolled bars.

Aug 16, 2017

By Gerhard Richter, Norbert Asamer, Gerwald Decker

At various stages during their manufacturing processes - from casting to finishing before delivery - semi-finished steel and special alloy products must be cut and surface-treated as well. The requirements for the individual conditioning steps, however, can be quite different. For example, the work piece can be hot, warm or cold. At any rate, the product must always be perfectly prepared for the next manufacturing step - reliably, in the shortest-possible time and at the lowest-possible cost. For cutting and grinding, BRAUN has developed innovative technologies and highly flexible, tailor-made solutions which meet these requirements in the most optimal way. In particular, BRAUN’s cutting and grinding technologies can also be used for large-scale products.

Oct 1, 2019

By Valeria Romina Stricker

Acerbrag es una empresa Argentina siderúrgica de 50 años de trayectoria, desde el año 2007 pertenece al grupo Votorantim de origen Brasilero. Se dedica a la elaboración de aceros largos para la construcción. La planta industrial cuenta con un proceso de acería integrado, horno eléctrico, horno cuchara y máquina de colada continua. La materia prima es 100% chatarra, característica que la diferencia del resto de las acerías del país. Debido a esto el enfoque principal de este proyecto es reducir el costo de fabricación mediante un “empobrecimiento” de la carga metálica a partir de la flexibilización de los límites de especificación. Esto implica un mayor control del desempeño de los procesos a fin de detectar posibles desvíos, para ello fue necesario implementar la utilización de herramientas estadísticas y gráficas para su monitoreo. La modificación en el mix de fabricación no muestra una alteración significativa en la composición química y propiedades mecánicas de los productos terminados, situación favorable para la continuidad del proyecto. Se observa además, de la reducción de costo esperada, una ventaja en la operación del patio de chatarra y el proceso de acería y en la utilización de chatarras con altos niveles de residuales tales como Cr – Ni.

Aug 16, 2017

By Javier Martinez Rubio

In this paper we will discuss the benefits of a very innovative way of introducing MgO in the blast furnace operation through the sinter, using mini lumps of dunite. By changing the traditional way of using an MgO bearing material in fines form (particle smaller than 5 mm), most of the MgO inserted material behaves as inert during the sintering process, with the effect of having the following parameters (among others) improved: productivity at the sintering bed, permeability inside the blast furnace, energy consumption, stability of the operation.

Aug 16, 2017