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By Peter Grawenhof

In steel mills universal joint shafts, slipper spindles and gear spindles are used to overcome the design- and process- related offset between the axis of the motors and the work rolls. At the roll side the available space for the couplings is limited by the minimum work roll diameter. This leads to extremely high loaded components of the universal couplings especially at the roll side joints. Furthermore modern steel mills continuously strive to roll larger plates and materials with increased strength. This requires drive solutions with even higher torque capacity. For these applications conventional design joints are not sufficient anymore. Even alternative solutions such as hybrid- or offset- designs fall short. Therefore the companies Voith and BUMA Engineering developed together the new GearLink drive concept in close cooperation with the Voestalpine Grobblech GmbH. A completely new combination of universal joints and gear couplings offers an up to now unique solution enabling the use of 1,35- times bigger joint with a 2,5- times higher torque capacity and a 20- times longer lifetime. The GearLink system was first time successfully taken into operation at Voestalpine Grobblech in December 2013 and is up to now working without issue.

Aug 16, 2017

By Giulio Rodrigues Altoé

Environmentally correct composites, made from natural fibers, are among the most investigated and applied today. In this paper, we investigate the mechanical behavior of epoxy matrix composites reinforced with continuous fique fiber, through bending tensile tests. Specimens containing 0, 10, 20 and 30% in volume of fique fiber were aligned along the entire length of a mold to create plates of these composites, those plates were cut following the ASTM standard to obtained bending tests specimens. The test was conducted in a Instron Machine and the fractured specimens were analyzed by SEM, the results showed the increase in the materials tensile properties with the increase of fiber amount.

Aug 16, 2017

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 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 Alberto Tremea

In this period a great attention is put on roll cost and the differences in roll behavior in very few situations move the existing balances. Among many variables that are taken into account to evaluate the roll there is the consumption which is normally calculated according to the tonnage rolled. In this work there is a review of some approaches that are used to evaluate the roll efficiency together a description of a new method to make this. The main purpose of this calculation method is to help the comparison of roll results used in different mills. There is the need to have a clear and univocal reference when it’s time to think about innovative products. At now there are available roll grades with excellent technological properties but it’s necessary to have the right tools for a careful evaluation of roll behavior to take a good decision.

Jul 30, 2018

By Marcel Antonio Arcari Bassani

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

Aug 8, 2018

By Rafael Abreu Fraga, Carlos Noberto Paula da Silva, Emanuelle Garcia Reis, Daniel Bojikian Matsubara

Since 2016 Gerdau Ouro Branco has been producing steel plates of various qualities and grades. However, it was not until 2018 that the first plates produced by accelerated cooling process were made available for external testing, in this case for large diameter UOE pipes manufacturing. Recent line pipe and OCTG specifications are showing that the oil and gas market still consumes regular API grades, such as X60, X65 and X70, however with increasing wall thicknesses, reaching values up to 1.5 inches. These specifications also demand longitudinal and transverse tensile guarantees and drop weight tear tests in temperatures as low as -40°C. Projects with these types of mechanical properties present process requirements as challenging as those necessary for higher API grades in lower thicknesses. This paper shows the steel design concepts and rolling routes for achieving the necessary properties for X70 steel plates in 28.15 mm. The microstructural features were also investigated and associated with the production process and the tensile and toughness results. Finally, challenges such as tensile anisotropy and DWTT abnormal fracture are presented.

Oct 1, 2019

By Eduardo Dominguez Trindade

Lubricant oils are subjected to reciprocating movement in the piston ring/cylinder tribocouple of automotive engines. In this kind of movement, the relative speed oscillates between zero and a maximum, and therefore the lubrication regime goes from boundary to hydrodynamic. Tribotests are widely used in laboratories to hint at the friction developed in these systems. In the present work, a SRV tribometer was used to evaluate the friction behaviour of lubricant oils under reciprocating movement up to 60 Hz. A high acquisition rate allowed the analysis of data inside each reciprocating cycle. Both a pure base oil and a fully formulated lubricant were used. Changes in the contact pressure, viscosity and speed were seen to influence friction, which was correlated to the relative thickness predicted by Hamrock-Dowson equation. While some observed characteristics were typical consequences of the Stribeck curve, other effects were also observed, such as the occurrence of seizure at high reciprocating frequency. A lower boundary coefficient of friction due to additive package in the formulated oil was also observed. The results allow a better understanding of friction in reciprocating cycles and can be used to evaluate the performance of oils and surfaces in laboratory prior to engine testing.

Jul 31, 2018

By Rainer Fackert

3D-Measurements for slabs and heavy plate are now available and close the gap in the production chain. The measuring systems described in this presentation must be seen as high-tech solutions in the field of casting and rolling technology. The measuring systems were developed taking into consideration the harsh casting and rolling mill environment in which they are to be used, with the aim of achieving high operational reliability and eliminating disturbances. Interconnected quality management systems enable optimization across the complete production process. New limits are being defined constantly for all these developments. What is technically feasible today becomes normal practice tomorrow, and will probably be replaced by completely new technologies the day after.

Aug 16, 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 Edo Engel

Hot Blast Stove Technology has been developed to such an extent that low cost hot metal production for over 30 years without major repairs has become achievable, making the decision for a campaign length between 5 to over 30 years a design choice for the plant owner/operator. Some of the earlier examples of designs capable of such long campaign lengths are currently close to the 50th year of their running campaign. These examples are found especially in Europe and North America. Along the duration of these campaigns, repairs to subsystems such as burners, hot blast outlets etc. may be required. Depending on a plant’s up and down stream production capacities, the repairs may have to take place in the shortest possible time frame to minimize production loss. This article discusses an approach for intermediate repairs, executed while keeping the majority of the system at operating temperature.

Oct 30, 2017

By 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 Samuel F. Rodrigues, Clodualdo Aranas Jr., Fulvio Siciliano

The application of thermo-mechanical control processing (TMCP) in hot rolling of steels has become a common routine since the last 60 years. The understanding of the physical metallurgy behind TMCP played a major role in the early developments. Physical and numerical simulation works are performed firstly to derive the fundamental metallurgical knowledge and secondly to conceive existing TMCP practices. In this paper, a summary TMCP techniques is presented. The occurrence of dynamic transformation of ferrite in the austenite region is shown by means of synchrotron light diffraction methods. This phase transformation mechanism is taken into consideration and its effects on TMCP are proposed in an exploratory way.

Oct 1, 2019

By Xihuai Gong, Hongshuang Di, Jianping Li, Ning Yan

In this work, we investigated the effect of the rolling process (warm-rolled or cold-rolled) on microstructure evolution and mechanical properties of 9Mn steel. After intercritical annealing at 670°C for 10min, both cold-rolled and warm-rolled microstructures are composed of ultra-fined austenite and intercritical ferrite. The austenite in warm-rolled sample includes two types of morphology, namely equiaxed and lamellar, which exhibits a wide distribution of grain-size. The incomplete recrystallization or recovery behavior of ferrite in warm-rolled and annealed sample results in higher yield strength and shorter yield point elongation. Moreover, the warm-rolled and annealed sample extends the TRIP-related work hardening over a broad strain range, resulting in a better combination of ultimate tensile strength and total elongation.

Oct 1, 2019

By Ramon Augusto Moretti, Henrique da Rocha Severino, Renato Nascimento de Castro, Fernando Cesar Sousa

Rolling stand 12 (LTx) of long steel, installed in the company A, Piracicaba - SP unit, had presented high levels of vibration, which affected its internal components, such as: shaft, gears and bearings, generating downtime. To evaluate this equipment a study was proposed by the following engineering techniques: Conventional Vibration Analysis, Operational Deflection Shape (ODS) and numerical simulation by the Finite Element Method (FEM). In the Conventional Vibration Analysis, high levels of vibration were observed during manufacturing process, especially when the material reaches the equipment. Impacts generate high values in acceleration, on average 80 m/s² peak to peak. In the moment of impact, misalignment of internal components was observed by ODS. Field results were correlated to those obtained by the Finite Element Method, which allowed to calibrate FEM model. Thus, the most effective structural modification already numerically evaluated was implemented in the system. Afterwards, new measurements by vibration and ODS techniques were performed, and attenuation of vibrational levels and operational mode, which overloaded the internal components rolling stand, were verified.

Oct 1, 2019

By Emanuelle Garcia Reis, Gustavo de Sousa, Rodney Pardo Alves

Gerdau Ouro Branco´s plate mill started the operation in 2016 with high level technology. In general, national and international plate markets are every day more rigorous about final product quality. Suppliers must be aware about dimensional accuracy, surface quality and flatness of the plates, independent of the quality standards. To guarantee the best service to this increasingly demanding and competitive market, it is extremely important to guarantee the original project conditions executing the right maintenance of the rolling mill main components. In order to maintain the product quality and avoid the production and maintenance cost increase, it is important to find ways to control the mill and the main process variables, through daily measurements of the equipment performance. This paper aims to present the influence of the main equipment variables that affect the mill operational stability and how to control and evaluate the mill performance.

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 Danilo Gonçalves de Oliveira, Rogério Martins Pereira

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

Oct 1, 2019

By 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 Diogo Tenório dos Santos

This property has been studied to characterize the strength a metallic material exhibits when it is machined so it can be regarded as its typical behaviour. As such, it may even be considered as an intrinsic material property. It is usually measured by an index called Coppini index, which is expressed by the ratio between the removed mass of a cutting tool caused by wear when it is used for machining and its initial one for a certain set of machining parameters. In this investigation, the tests were therefore conducted by an established set of parameters, namely feed rate, cutting and depth rates, in which the same wear mechanism took place in both ferrous alloys: AISI 4140 and AISI 316 steels. They were chosen based upon their increasing ordinary machinability indexes. The initial and final mass of the cutting tool were measured by an analytical scale with 0.01 mg precision. Cylindrical rods of 50-mm diameter were machined and the CI indexes showed a remarkable difference between them: 0.080 for the first steel and 0.049 for the second one, i.e., AISI 316 steel presented better machinability than the first one. It was then possible to conclude that this method presents good results in terms of both reproducibility and adequacy for machine shop conditions and it may be applied in a foreseeable future, mainly for metallic materials that have rather low machinability indices.

Jul 31, 2018