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By Gajraj Rathore

With the advent of modern HRM ( Hot rolling mills) with capacities beyond 5 Million tons with corresponding enriched CRM (Cold Rolling Mill) capacities, the throughput per hour exceeds invariably beyond 50 coils per hour making it possible to manage, track, handle, transport, store and dispatch inevitably with an automation system supplemented by corresponding software and hardware. This is true with respect to the production of Cold rolled Annealed, Galvanized, Continuously Annealed, Galvalume, CRGO, CRNGO and Colour coated coils which need total care in handling, tracking and dispatch. Understanding the above needs precisely JSW, Vijayanagar, India, has rightly gone in for a total automatic Yard management system and ASRS wherein the coils are handled as much as possible automatically in cradles without any damage insuring the receipt of coils to the customer as was produced. This CRM 2 has been commissioned and is operating with maximum automation with least manpower and max productivity with assured quality and safety. Pesmel OY Finland had the opportunity to Design, Supply and Commission this system which is first in the country and this technical paper analyses the above project as a case study enlisting the sound technical aspects as well as emphasis on the techno economics with assured ROI (Return on investment) and enhanced efficiency.

Aug 16, 2017

By Cermets

Ti(C,N)-based cermets offer good high temperature strength, perfect chemical stability, excellent wear resistance, and relativly better machinability. In the present work, the tribological behaviors of Ti(C,N)/SiC sliding pairs lubricated in water and seawater were evaluated using a ball-on-disk tribometer. The experimental results show that a relatively low friction coefficient (about 0.025) can be obtained when lubricated with artificial seawater at the sliding speed of 200 mm/s, while the date is about 0.2 in purified water. The wear surface profiles and the lubricants collected after running-in process for the high/low friction conditions were compared. In addition, the effect of salt molar concentration of the lubricant on the Ti(C,N)/SiC friction properties was investigated. It was found that the smooth and flat surface is the premise to gain the low friction. At the same time, the proper concentration of silica colloid, which is affected by the salt ions, is also an essential one. Moreover, the high sliding speed (200 mm/s) is beneficial to achieve low friction.

Jul 31, 2018

By Frank Schrama

Steelmakers worldwide agree that the most efficient and cost-effective solution in BOF steelmaking is to desulfurize the hot metal between the blast furnace and converter. Various methods are currently in use, among which the Kanbara Reactor (KR, using only lime as a reagent), Magnesium mono-injection (MMI, using only magnesium; also known as the Ukraina-Desmag process) and co-injection (using magnesium and lime/CaC2) are leading. These three hot metal desulfurization methods are compared based on metallurgy, efficiency, costs and overall performance. Both available data from literature and experience from Danieli Corus engineers is used for this study. The KR process is able to reach low sulfur concentrations (> 10 ppm) in hot metal and has lower reagent costs. However, due to higher Fe-loss and heavy wear the KR process has the highest operational costs. The Magnesium mono-injection process is very fast due to the use of the reactive magnesium as reagent. Major problems with resulfurization (sulfur levels below 50 ppm cannot be reached) and the violence of the process made that this process could never get a firm foothold in the western steel industry. The co-injection process with magnesium and lime proves to be able to combine the best of both worlds. It can reach low sulfur concentrations and desulfurize fast. Co-injection is also the most flexible and cost effective.

Aug 16, 2017

By Wilian da Silva Labiapari

Austenitic stainless steels are widely known for their good weldability, excellent mechanical properties for deep drawing and superior corrosion resistance in environments where most of the metals fail. Their uses include many applications subjected to a combination of mechanical and corrosive wear, such as pumps, valves and surgical implants. Although their corrosion resistance has been largely investigated, their resistance to mechanical wear is less studied. In particular, their performance under conditions involving combined corrosive and mechanical wear is not well understood. The aim of this study is to demonstrate the effect of the mechanical component on the electrochemical signal of an anodic polarization curve. A test rig was developed to investigate micro-abrasion-corrosion using a fixed ball configuration. Tests were carried out using stainless steel AISI 304 samples and 25.4 mm zirconia balls as counter bodies. The electrolyte was a 1N H2SO4 solution with SiO2 as abrasive dispersed at the concentration of 10 wt%. The results showed an increase in current density when the counter face roughness and the normal load applied during the tests are increased, evidencing a mechanical influence on the surface activity of this material in a corrosive environment.

Jul 31, 2018

By Andrea Codutti, Gianni Tiussi, Andrea Tonnicchi, Morris Codarin

Essar Algoma Steel, Canada, awarded Danieli Transimissions a strategic order for the upgrade of the main drive spindles belonging to the most loaded stands of the Hot Strip Mill, F1-F2, F5 and F6. Featuring special heavy duty design and advanced torque monitoring system, these spindles replace existing competitors’ grease lubricated design with the efficient continuous oil lubricated solution to withstand the tough working conditions, increase life expectations and provide room for a product mix extension. The first couple of spindles have been installed in September 2017 by the expert Service team and are showing already good and reliable performance. Progressively all the others are being installed.

Oct 1, 2019

By Cameron Soltys, Hamid Ghorbani, Maher Al-Dojayli

Cooling staves in blast furnaces are used to minimize the process heat loads on steel shell and refractory system. Copper staves are exposed to significant fluctuating thermal loads which may lead to premature stave failures due to cracks, water leakage, bending, abrasion and resultant wear. In this paper, an assessment methodology is presented to evaluate the effect of thermal cycling on copper staves including bending, fatigue and thermal ratcheting. This approach incorporates temperature-dependent copper properties including creep and plasticity to more accurately capture inelastic deformations, damage and fatigue in staves under transient and cyclic thermal loading conditions. Root cause failure assessment and improvements to copper stave design can be assessed using the presented methodology.

Oct 1, 2019

By Baoliang Xiao, Hui Pan, Yajun Hui, Kun Liu

The microstructure, properties, strengthening mechanism and work hardening mechanism of 600MPa grade high ductility hot-rolled sheet steel for automotive square tube were investigated by utilizing optical microscopy, scanning electron microscopy and transmission electron microscopy. The results show that the microstructures of low C-low Mn-Nb and Ti microalloyed steel (Steel A) and high C-high Mn-Nb microalloyed steel (Steel B) are composed of ferrite and a small amount of pearlite. Compared with steel B, the size of ferrite and pearlite of steel A is finer, while the size of the second phase precipitates is larger. The mechanical properties of the two tested steels are similar before tube forming, except that the yield ratio of steel A is higher. Steel A has/exhibits significant work hardening after tube forming; the yield strength and tensile strength increase by 45 MPa and 26 MPa, respectively, while the elongation decrease by 6.0 percent. The yield strength and tensile strength of steel B increase by 22 MPa and 10 MPa, respectively, and the elongation decrease by 4.0 percent. The grain refinement strengthening is the dominant strengthening mechanism, accounting for 52.9 to 61.8 percent of the total yield strength; the solid solution strengthening is the second strengthening mechanism, accounting for 17.2 to 25.3 percent, while the precipitation strengthening and dislocation strengthening contribute little to the yield strength. The dislocation strengthening increase by 82 MPa of steel A after tube forming, which is higher than that of steel B. Therefore, steel B has a low work hardening rate that is more suitable for manufacturing automotive square tube for secondary tube forming.

Oct 1, 2019

By Luiz Henrique Accorsi Gans

First, this works carries an experimental evaluation for austempered ductile iron (ADI) as a gear material. And second, in order to provide a better understanding of the microstructural effect on the stress state of subsurface regions, a finite element method approach was considered using the submodeling tool in ANSYS 11.0. For this, ADI gears were produced from continuous cast iron bars, heat and thermochemical treated and tested in FZG test rig. The results were compared to those of carburized steel AISI 8620 and induction hardened steel AISI 4140 gears. The wear experiments were performed at the temperature of 90ºC with two torque stages: 135 N.m (running-in) and 302 N.m (steady-state). The time for pitting and spalling on the gears surfaces were measured using image analysis. The results showed a very good potential of using ADI for manufacturing gears, replacing induction hardened steels. Also, the ADI gear with smaller nodules showed higher life for pitting. In contact fatigue tests with severe load, the carburized AISI 8620 steel proved more adequate than the austempered ductile iron, showing that the mechanical properties are critical in the resistance to damage in gear contact. The austempered ductile iron with smaller nodule size showed to be very competitive with wear resistance similar to AISI 4140 steel induction hardened. With ANSYS, it was verified that the nodule size affects the gears life independently of the mechanical properties of the matrix. The results showed that the nodules indicate the presence of a concentration stress, but their size doesn’t affect the contact fatigue life as much as the total amount of nodules, regardless of the ductile iron microstructure. The size and number of nodules affects both the nucleation and the propagation stage of cracks. ADIs with higher amount of nodules have a greater wear resistance. Also, compared to the Hertz contact theory (isotropic material), the presence of graphite nodules indicates a non-isotropic material and made the maximum shear stress point moves toward the surface.

Jul 31, 2018

By Filippo Verlezza

Conventional wire rod blocks have some limitations. They can only roll with fixed reduction ratios which always require the same rolling diameters within the block. With MEERdrive® SMS, as a pioneer, has introduced an innovative drive concept for wire rod blocks that can overcome the limitations of conventional solutions. The clue: the concept is based on individual drives for each stand position. The exigent wire rod market demand and the available technology melt in a new variant of MEERdrive®, the MEERdrive®PLUS, which represents a sizing block solution for finished size rolling and allows conventional as well as thermomechanical rolling. Further “one family rolling” is also possible, since all roll / size changes will occur in this block.

Oct 30, 2017

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 Alain Denis, Marcelo Curtes Martins, Jeferson Rocio de Oliveira

In this work we present a study of optimization of a new inhibitor for turbulence pickling line. The efficiency of inhibition was measured and the weight of loss was evaluated in four different materials to optimize the dosage of the inhibitor. In seven months we had 8.7% of reduction in pickling losses.

Oct 1, 2019

By Cristiano José Scheuer

Experiments were carried out aiming to study the influence of micro-abrasive wear test variables and plasma treatment parameters, on the tribological characteristics of low-temperature plasma carburized AISI 420 steel. The first part of this study was conducted in order to evaluate the influence of abrasive particle size, normal load and counter body rotation speed on carburized sample wear behavior; and the second part was conducted in order to evaluate the treatment temperature and time effect on carburized samples wear behavior. Plasma carburizing treatments were performed at 8 and 12 h, for temperatures ranging from 350 to 500°C; and at constant temperatures of 400°C for times between 12 to 48h, and for 450°C for times of 4 to 16h. Micro-abrasive wear test were performed by mean of a calowear ball-cratering equipment using a polished ball of AISI 52100 steel rotating at 80, 120 and 160 rpm, for sliding distances from 2.6 to 104.2 m. Alumina abrasive particles with sizes of 0.05, 0.3 and 1.0 ?m were employed. The normal loads applied on this study were 0.1, 0.3 and 0.5 N. Carburized sample was characterized by mean of OM, XRD and hardness measurements. Worn crater characteristics were evaluated by confocal laser microscopy. Results showed that the transient wear regime prevails along the outer layer length (composed by Fe3C and ?’C), and the steady-state wear stabilizes in the diffusion layer region (composed by ?’C). It was verified that the wear rate and wear coefficient decreases with treatment temperature in the range of 350–450°C and increase for 500°C. It was also verified that the wear rate and wear coefficient decreases with treatment time in the range of 12–36 h (for 400°C cycle) and 4–12 h (for 450°C cycle), and increase for larger treatment times due the chromium carbide precipitation. It was also found that the wear coefficient increases with the increase of abrasive particle size, and decrease with the increase in counter body rotation speed and normal load. Lastly, the analysis of the worn craters indicates the occurrence of grooving and micro-rolling abrasion wear mechanisms.

Aug 17, 2017

By Günther Staudinger

Danieli Linz Technology has been honored at 4.1.2013 with the first contract for the exchange of a 350 t BOF converter for ArcelorMittal Poland Dabrowa Gornicza on a turnkey basis. This paper describes the new design features of this converter based on the development of a new Danieli converter suspension system. The issue was to install a new converter (incl. trunnion ring, suspension system and bearings) with maximum volume but keeping most of the existing equipment unchanged. So, the big tilting drives on both sides had to be reused and the existing foundation, pedestals as well as the bearing distance had to be maintained. Further on the welded coreequipment (vessel shell, trunnion ring, pedestals, slag shields, etc.) was manufactured in-house within the pressure vessel division of Danieli Thailand. Due to the huge dimensions of these parts the delivery had to take place in parts which had to be welded together on site under full production conditions of the steel plant. But also the erection had to be applied under this condition. Additionally the main support bearings, parts of the screening (doghouse) as well as an upgrade of the existing relining machine had to be delivered.

Jul 29, 2018

By Rainer W. Kaiser

High wear resistant HSS rolls are being successfully used in the first stands of HSM finishing trains since the early 1990´s. The strong demand of mill administrators to make them applicable also in the last stands of the finishing rolling mill is a major influence factor of R&D efforts at respective roll suppliers. Looking back to the successful replacement of ICDP and HiCr rolls by more economic HSS rolls in F1-4 in regard to the TCO, rolling mill managers wish to repeat such scale gain also at F5-7 stands. Actually used enhanced ICDP rolls wear faster, being the HSM stoppage factor. F1-4 HSS rolls can be used for example 3 times longer. There is an obstacle to be overcome by roll suppliers and end users to replace F5-7 rolls by HSS rolls. Stick and crack resistance properties of HSS need to be improved. As a worldwide known leading producer of cast rolls for steel mills since 1820, the traditional German family owned foundry and machine shop IRLE, existing since 1693, accepted to face also this additional challenge. IRLE´s long year experience and prior researches have shown possible development directions to improve mentioned stick and crack resistance properties of its HSS grade, called SST. A new material of the HSS family is in the development pipe line and is discussed: SST/G. Choice criteria of the development direction, steps to control and guarantee respective sections of an industrial scale production as well as observations and results are described.

Jul 30, 2018

By Beatriz Dogliani, Elisabeth Williams, Maria Berenice Sandobal, Carina Bertino

The environmental management of steel mill slag should be understood as a management philosophy, observing technical, economic and environmental criteria associated with their generation, storage and final destination. The slag can be considered as a synthetic mineral resource and become a very useful co-product in different areas. The Argentinean steel industry prioritizes the efficient environmental management of its waste, thus contributing to its own survival taking into account the sustainable development. In the world, the slag produced by the steel industry has been used as steel aggregate for road bases, railway ballast and filling material among others. Any factor that influences the economy of the country affects all branches of society, mainly public agencies, whose financial resources are increasingly scarce to deal with all public works. It is necessary to join efforts of private and public initiative in the adoption of alternative materials that replace the use of finite natural resources. This presentation aims to show the work done by private companies together with public bodies and universities to obtain a regulatory document for the management of slag as steel aggregates for three different uses, namely: road use, railway use and general use.

Nov 5, 2019

By Renan Oss Giacomelli

The adhesion of multifunctional coatings on soft substrates is of paramount importance in the tribological behavior of this important class of surface treatment. In particular, scratch and indentation tests have been extensively used in order to assess this property. In this paper, the adhesion of a-C:H diamond-like carbon films deposited on nitrided low carbon steel was evaluated by indentation and scratch tests. The coatings were produced by PECVD onto 1020 steel substrates with two different surface finishing: ground (Sq = 0.184 µm) and polished (Sq = 0.002 µm). Indentation tests using a Rockwell diamond indenter were conducted and the adhesion evaluated by measuring the spalling region on images obtained by using optical microscopy. The analysis of the spalling regions produced semi-quantitative results, eliminating the subjective qualitative analysis proposed by the standard method VDI 3198. In addition, scratch tests were performed using the same indenter and a comparison between the two techniques was established.

Jul 31, 2018

By Aaron Samuel Young, Hiago Antunes Amador de Oliveira, William Pratt Rogers

Low commodity prices and lack of new high-grade deposits are pushing the mining industry for innovation. Lean mining has been vastly discussed in the past decades as a way to continuously improve mining efficiency. Although very theoretical, lean mining presents a set of new solutions enabled by the digital transformation that the mining industry is going through. This paper proposes a framework for a short interval control system with the purpose to allow timely responses by front line supervisors upon operational deviations. In the first part, the author briefly reviews concepts of short-range planning and lean mining. Then, the materials and methods used for the development of the short interval control system are discussed. Finally, alpha trial results are presented, and next steps discussed.

Oct 3, 2019

By Hui-bin Wu, Rui Yuan, Yang Gu, Peng-cheng Zhang, Zheng-zhi Zhao

The corrosion behavior of three kinds of medium-Cr rolled steel pipeline steels in carbon dioxide collecting and transporting environment at different temperatures was studied. The results shew that the 5Cr sample was most affected by temperature. When the temperature rised from 30 °C to 90 °C, the corrosion rate increased from 0.12 mm/a to 1.87 mm/a, which was increased 15.6 times. The corrosion rate of 7Cr steel at 30 °C was similar to that of 5Cr steel. However, as the temperature increased, the corrosion rate rised slowly, increasing by 2.4 times at 90 °C. The corrosion rate of 9Cr steel was not obvious with temperature, and it was always below 0.06 mm/a. The thickness of the corrosion product film of the three samples gradually increased below 70 °C, and suddenly increased above 70 °C. This was related to the negative temperature coefficient of the solubility of FeCO3, and the thickening of the product film also affected the ion exchange of the cathodic reaction. An increase in the Cr content contributed to grain refinement and increased the proportion of the small-angle grain boundaries. More fine grains mean an increase in the total length of the grain boundaries, which could provide a diffusion channel for the free Cr element; on the other hand, the low-angle grain boundary structure was more orderly, with a lower free volume and lower interface energy. Under the combined effect of both, 9Cr steel and 7Cr steel had high volta potential and better corrosion

Oct 1, 2019

By Luiza Esteves

Corrosion testing was performed in white liquor from a Brazilian Kraft mill. Specimens of duplex stainless steel (DSS) and lean duplex (LDSS) were exposed at 170 °C for 30 days to simulate conditions of the digester. Corrosion rates were determined from weight loss measurements. After this exposure, the corrosion products formed on the steel surface was characterized by using scanning electron microscope (SEM) equipped with EDS, X-Ray Diffraction (XRD), and X-ray photoelectron spectrometer (XPS). EBSD can be used to quantify of basis balance phases in DSS and LDSS. General corrosion rates for UNS S32304 LDSS were higher than the UNS 31803 DSS in industrial white liquor at 170 °C for 30 days. XPS and XRD analyses indicated that the film formed after the immersion test may be consisted by Fe and Cr oxides and sulphides.

Oct 30, 2017

By Sebastien Maillard, Stephane Georges, Thomas Vallee, Stanislas Mauuary

Steel strip manufacturing ever reinvents proposing new grades, requiring to tackle technical limitations of production systems. Primetals Technologies breaks through strip welding by expanding the welder LW21L “Asolid” technology used on low gauges for high-end market such as automotive CAL/CGL. Addressing the usual drawbacks in maintenance, operation and safety of current welding system based on mechanical cutting and CO2 laser welding, the newly developped LW21H “Asolid” technology processes thicker strips up to 7 mm with solid-state laser cutting and welding. This new welder is brought to reality through a scale 1:1 pilot developed, manufactured and tested in Primetals Technologies workshop.

Oct 1, 2019