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By Márcio Corrêa de Carvalho

Welded deposited chromium carbide overlay’s has been widely used in various branches of welding overlay’s industry related to wear. Characterization techniques are an important tool in the development of chromium carbide overlays resistant to wear, enabling the identification of phases, constituents and defects. In this work one used optical microscopy, scanning electron microscopy and energy dispersive spectroscopy on chromium carbide overlay’s deposited by submerged arc welding process. The characterization techniques identified precisely the elements of the overlay’s enabling point of the main cause of the observed defects such as cracks, porosity and clusters of particles known in the industry as " rice crispy" .

Aug 16, 2017

By Paul Riches

LR Process Expert is a cost-efficient process automation system for all types of long rolling mills, including, rod, bar, section, rail, reversing mills, and flat blocks. The system performs a wide range of tasks for optimized operation – from suggesting pass schedules to calculating and downloading optimized mill settings according to the availability of rolls. LR Process Expert also monitors and collects data from the raw material stage through to the finished product. It delivers valuable mill reports to the operator staff and management so they can easily assess a plant’s performance and optimize production. Defined Key Performance Indicators (KPIs) help to assess a plant’s performance; this system is not limited to one plant but can enable plant-toplant performance at corporate level.

Aug 16, 2017

By Gustavo Borges Tiboni

The erosive wear caused by the impact of solid particles against a surface is a tribological phenomenon present in many segments of the industry, such as transportation, aerospace, mining, power generation, among others. The most usual method to set the wear rate is by measuring the mass loss of the material. In order to apply one technique with potential to determine the rate of erosion wear, this study developed a dedicated equipment and conducted preliminary erosion tests monitored by non-destructive testing known as acoustic emission technique (AE). This can be defined as a technique able to detect mechanical waves generated by the release of elastic energy accumulated in the material. Erosion tests were performed in order to evaluate the ability of equipment to collect data from AE and to correlate these data with the wear of the samples. Samples of low carbon steel eroded by the impact of angular aluminum oxide particles suspended in air at three different velocities: 45, 57 and 67 m/s. The impact angle between the particles and the sample was set at 30 degrees and the test temperature at approximately 20°C. The wear rate has changed with the velocity in accordance with the kinetic energy of the particles and the AE parameter RMS showed sensitivity to the variation of particle impact velocity and to the wear of the sample eroded. The rate of AE signals collected over time correlated with the flow of particles striking the sample, and with the parameters of energy, rise time and duration of the signal.

Jul 31, 2018

By Luiz Bruno de Oliveira Araujo, Luciano Morais Teixeira, Luiz Gustavo Pedrosa de Melo, Altair Lúcio de Souza

The off-line simulation of the metallurgical process in an industrial line brings several benefits such as: evaluation of the influence of the main parameters that affect the results of the process, comparison between different set ups, greater assertiveness in operational adjustments, process optimization and reduction tests for development of new products. With this objective, a software for offline simulation of the hot strip mill process of Gerdau Ouro Branco was developed based on the logic of calculations implemented in the online model. The software results in important process variables such as mill pass scale, load, torque, and power at each pass, temperature and the hot mean flow stress of the simulated material. During rolling mill process the strip presents different temperatures and time between passes for different points along the length, which directly influences the hot strength of the product and consequently in the calculated variables, thus the calculations executed by the software were divided to three points of the strip, head, body and tail bringing the individual results to each of these positions.

Oct 1, 2019

By Jürgen Schanderl

Cold rolling mills by SMS Siemag are well known for their reliability and long-life cycle. They are an investment in the future. Nowadays mill owners are under considerable competitive pressure and are asked to organize production in a more and more efficient and flexible way. Doing so, a number of elevating screws have to be turned. These are: cutting of operation costs, especially by more efficient equipment and processes as well as transition to more process flexibility to fulfil future product requirements. To support owners in their effort, SMS Siemag offers convincing solutions in cold rolling technology under the brand X-Roll 2.0. Examples to be presented are: Sieflex®-HT drive technology; Redesigned DS system; New reel design: Twin Reel; Emulsion compact unit ECU Compact; TRC® threading assistance system; ECOMode and Energy ADVISOR monitoring system.

Jul 30, 2018

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 Wolfgang Kern

More and more coke oven plants worldwide face the task to improve their emission reduction at their coke oven batteries. In the 90’s PROven® was invented and developed by DMT to regulate the inner pressure of a single coke oven chamber. Generally, most of the coke oven chambers can only close and open their connection to the collecting main but without the possibility to regulate the pressure during the carbonization time. Through the installation of PROven® the load on the coke oven door sealing system and the charging lids will be decreased and so does the emissions of crude COG as well. The current PROven® system, installed in the collecting main, does not only regulate the chamber pressure, it replaces the valve between the goose neck and the collecting main, too. This variable pressure control allows decreasing the leakages at the emissions sources to a minimum and allows operating the collecting main under optimum pressure. Subsequently, this will lead to enhanced emission reduction. PROven® proved its value with more than 2,100 units installed by licensee worldwide. Nevertheless, DMT is always focused on its client’s needs and therefore enhance PROven® to provide the Best Available Technique (BAT). Among the main features of the now available system is the plain arrangement with a higher reliability and the possibility to install the system outside of the collecting main without modifying it. Hence, upgrading coke oven plants during operation is possible without any noticeable impact on the plant operation.

Aug 1, 2018

By Michel Rodrigo Luiz, Glaucio Augusto Polini, Leonardo de Souza Melo, Giovani Rodrigues, Giardini F. Lazzarin

ArcelorMittal's pickling and cold rolling line has been demanded to increase production since the installation of equipment in 2015. In addition to improving productivity related to these new equipment, several additional jobs were planned and executed on equipment already installed has been carried out in order to improve the efficiency of the line. The present work exposes what was done in the scale breaker (tension leveler) to improve the availability results of the section and consequently of the line.

Oct 1, 2019

By Silvio Cecchini

State-of-the Art Mould Level Control Solutions for continuous casting applications face different challenges. On the one hand, technological phenomena such as clogging and unclogging, unsteady bulging or waving can create unpredicted meniscus disturbances by completely changing the casting channel geometry and the flow behaviour of liquid steel to the mould. On the other hand, from the viewpoint of caster operations, long lifetime, quick interchange-ability and integration capability into existing systems must be achieved. In the present contribution, the overall development of INTECO TBR’s mould level master – a comprehensive mould level control solution for all continuous casting applications – will be introduced. The basis for the presented system is a development over several years which includes investigations of all critical components such as shroud, stopper, stopper mechanism, servo actuator and mould level control program. These investigations finally resulted in a new-ly developed control algorithm for a highly dynamic servo actuator. The control algorithm with its basic functionality such as the prevention, identification and removal of clogging impacts with the associated automation functions to reduce their influence onto the overall mould level control performance will be presented. The scientific basis, the resulting control functions and their related automation implementation will also be illustrated. Finally, a patented control algorithm and control functionality for unsteady bulging and waving effects with the associated automation functions to reduce their influence onto the overall mould level control performance.

Aug 16, 2017

By Ronaldo Esteves Ribeiro, Jefferson Felipe Faria Clemente, Carlos Victor Francisco dos Santos, José Herbert Dolabela da Silveira

n recent years, the market for thick plates has been highly competitive, in this scenario the plates quality is a critical success factor. In this process, the quality of the cut in thick plates is one of the important requirements for the customers, by the visual aspect as well as the technical aspect of the plate application. In the shear line, the cutting is done by shearing to trim tips, subdivide plates, trim side edges, remove samples, eliminate defects, etc. The cut is obtained by the penetration of the upper knife in the plate, causing plastic deformation in a certain region and hardening. If the clearance between the knives is adequate, the cracks will be close to the centre of the plate thickness and will result in a good cut quality. This work will present the theory of cutting of thick plates, the types of shearing, the quality of the edge in the cut, the types and the main characteristics of the knives.

Oct 1, 2019

By Fabiano Almir Barbosa, Eduardo Alves Machado, Felipe Ferreira Cajano, Bruno Rodrigues Henriques

Spring steels are usually classified as medium to high carbon low alloy steels with very high yield strength, enabling the part to return to its original shape regardless of significant bending or twisting. Despite the fact that plain carbon steels are suitable for small springs, larger and high performance springs usually requires alloy steels such as Cr-V or Si-Mn in order to achieve an even microstructure throughout the cross section. Clutch diaphragm spring is a high performance part that requires very good cleanliness and microstructure homogeneity, thus requiring an alloy steel. In this paper was studied, in an industrial scale, the process parameters and critical characteristics for the development of a Cr and V alloyed high carbon sheet steel for the production of clutch diaphragm spring. The steel was characterized throughout the entire process (casting, hot rolling, cold rolling + batch annealing and heat treated) using tensile test, hardness test, optical microscopy (OM) and scanning electron microscopy (SEM) to assess the mechanical and metallurgical properties of the studied steel. The results have shown the material’s microstructure evolution after each main stage of the process, from a ferrite-bainite/perlite based microstructure as hot band to fully spheroidized as cold-rolled/annealed and then fully martensitic as ready-to-use part.

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 Osvaldo Guilherme Comineli

An extensive investigation into the role of low copper contents on the hot ductility of C-Mn-Al steels has been carried out in order to better understanding the problem of “hot shortness”. Previous work has suggested that this problem results from the build up of Cu that occurs at the surface of the steel as a consequence of the preferential oxidation of iron. This causes the formation of a Cu-rich film of low melting point. A nickel addition has been reported as a solution to the problem, since it increases the solubility of copper in the austenite. After hot tensile testing to failure, samples of Cu-containing steels have been examined using optical, scanning and transmission electron microscopes. Recently published results indicate that copper, in addition to precipitating out as CuS, also segregates to MnS inclusions forming a shell around them. This does not seem to impair the hot ductility under an inert atmosphere, but may have serious consequences under an oxidising environment and lead to “hot shortness”. The influence of nickel in improving the hot ductility seems to be due to it forming a higher melting point alloy with the segregated copper. Data from this incomplete work also suggests that Ni reduces the precipitation of CuS particles. Current investigation carried out using confocal microscopy still to be completed will improve the understanding of the role of copper and nickel on the problem of “hot shortness”.

Aug 8, 2018

By Gilmar Zacca Batista

The present work is a part of a comprehensive program that aims to evaluate the girth welding procedures for heavy wall API 5L X65 pipes produced for sour service applications. This article describes the results of toughness, strength and sour resistance of girth welds produced with different welding consumables. The methodology applied included girth welds production with GTAW process for root pass using ER70S-6 consumable and FCAW process for filling passes using E71T- 1CJ and E91T1-GM-H4 consumables. Mechanical tests of Charpy, CTOD, tensile, hardness and stress corrosion cracking were also performed. The E71T-1CJ resulted in a girth weld with tensile and yield strength around 7% lower than the pipe. However, according to the papers analyzed at this study, a value up to 10% of undermatching could be acceptable. The CTOD and Charpy tests showed good toughness and weld metal embrittlement was not observed. The hardness and the stress corrosion cracking tests demonstrated that the consumable ER70S-6 is suitable for sour service. All properties evaluated met the requirements specified by the onshore pipeline standards, showing that the consumables ER70S-6, E71T-1CJ and E91T1-GM-H4 are suitable for the welding of heavy wall X65 pipe with sour service and toughness requirements. If an overmatching is required, the E91T1-GMH4 shall be used to assure a strength overmatching and prevent plastic strain concentration at the weld metal. The results provided by this paper can be used for consumable selection and for welding procedure qualification of pipelines construction when heavy wall API 5L X65 are used for sour gas transportation.

Aug 16, 2017

By Thomas Höfler, Michael Auinger, Bernhard Linder

Gas-fired pusher furnaces are commonly used to heat steel slabs before hot rolling. Temperatures well above 1000 °C combined with an oxidizing atmosphere containing H2O, CO2 and O2 result in rapid oxidation of most steel grades. The resulting oxide scale and the chemistry of the metal-scale-interface are major determining factors for the occurrence of hot rolling defects. To better understand these phenomena, lab-scale trials were performed with two different steel grades in an electric tube furnace in the temperature range 1000-1250 °C, using an atmosphere of about 20 % H2O, 7 % CO2 and 3 % O2. Humidification of the gas was achieved by evaporation, using a custom thermostat with standard laboratory glassware. The resulting samples were prepared metallographically, using cold mounting under vacuum with taper section angles, and analyzed using light microscopy and SEM/EDS. The scale structure of the Si alloyed steel was highly dependent on the oxidation temperature due to the formation of eutectic liquid phases of FeO, Fe2SiO4 and FeAl2O4. Below the eutectic temperature, the scale of the Si steel appeared to be made up of three distinct areas: The external scale consisting solely of Fe oxides, the internal scale containing Fe2SiO4 and FeAl2O4, and an internal oxidation zone with SiO2 and Al2O3 in a mostly plain Fe matrix. Comparisons of the experimental results with simulations of the internal oxidation showed good qualitative agreement.

Oct 1, 2019

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 Ian James McDonald

Each year, approximately 400 million tons of blast furnace slag is produced worldwide with a tapping temperature of around 1,500°C. It is normally used as a substitute for cement clinker or as an aggregate material in road construction. Currently, the slag is granulated in wet-granulation plants using large volumes of water and to date, it has not been possible to utilise the remnant heat energy of the molten slag, which amounts to approximately 1.8 GJ of energy per ton. However, in an R&D project currently underway led by Primetals Technolgies and industrial partners, a new dry atomising technology is being investigated to use air to cool molten slag and recover the lost heat energy. The resultant pelletised slag fulfils the same criteria as wet-granulated slag for use in the cement industry. Phase 1 of the project has now been completed where a technical plant was set up at the University of Leoben in 2012. A series of dry-slag granulation campaigns were carried out using remelted blast furnace slag. The elevated offgas temperatures and the quality of the slag product as verified by the FEhS Building Material Institute have shown the process suitability as an industrial application and the decision was taken to escalate the project from large laboratory scale to a full size pilot plant. The phase 2 development of this plant is now underway and is scheduled for installation at the site of an industrial partner in early 2016 where full slag flow will be fed directly to the plant from Blast Furnace ‘slag runners. This paper will show the development path taken to date and the planned route to our goal in 2016 of being the first to industrialise the ‘game changing’ process of dry Slag Granulation with Heat Recovery from the slag.

Aug 16, 2017

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 Gigliola Salerno

The carbon-epoxy composite has high specific resistance and strength, which means specific applications. However, its behavior under compressive stress could be decreased by delamination, needing more detailed studies. The main purpose of the present work is to verify the mechanical properties in bending process considering two different fiber orientations. The composite materials were made by woven fibers and epoxy resin. Primarily, the carbon fiber fabrics suffered a superficial physical treatment called silanization, in order to developing a better chemical adhesion between fibers and resin. After the superficial treatment, the layers were embedded with epoxy resin. The composite resin’s cure was made in a Fanem heater, model 320, during 1 hour at 120°C at 1.5 bar; subsequently the specimens were cut by water jet. Specimens oriented in 0°/90° and 0°/90°/45 were manufactured and taken to bending tests, accordingly to the ASTM E855 and D790 standards, in an universal testing machine MTS – Material Test System, full capacity of 250 kN. It was concluded that all specimens failed by tension. Specimens with internal void volumes results in lower flexural modulus and those with presence of fracture mechanisms, like delamination, showed lower strength values. Scanning Electronic Microscopy demonstrated the damages involved during bending process.

Oct 30, 2017

By Michael Windhager, Karl H. Ziehenberger

ULTIMA® are high performance, centrifugal cast, double poured (CC duplex) work rolls. This paper describes the principle of the ULTIMA® roll concept and its wide range of usability. The ULTIMA® concept provides a solution for rod and bar mills to increase performance and output, even under harsh rolling conditions. The main focus is on highly loaded mill stands that require both high wear resistance and resistance against thermal fatigue, like pre-dog bone, dog bone, slitter. Specific case studies of quite different mill configurations and rolled product mix prove the positive impact on production yield, mill and roll shop operations, and profitability in terms of TCO (total cost of ownership).

Oct 1, 2019