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By Kazuya Nakabo

In this article, influences of restraint and MgO content on densification of alumina-magnesia castable during heating were experimentally studied. High thermal expansion-alumina-magnesia castable specimens were surrounded by low thermal expansion-alumina-silica castables, and heated in an electric furnace. Doing so allows restrained heating of alumina-magnesia castable. According to the results of simple calculations, the restraint stresses were estimated to be between 2 to 20 MPa, so the experimental conditions were considered reasonable. As a result of the experiments, it was verified that restraint densifies alumina-magnesia castable, resulting in an increase in modulus of rupture and modulus of elasticity. The densification effect of restraint became larger as the MgO content increased. The effects are attributable to an in-situ spinel forming reaction, which improves corrosion resistance.Taking the temperature distribution in the castable lining into account, large restraint stress is expected for the hot face while only a little effect is expected for back end. Thus, excessive difference in material property in the thickness direction, which is undesirable in terms of structural spalling, is a concern.Hence, the MgO content of alumina-magnesia castable should be determined carefully, taking not only corrosion resistance but also spalling resistance into consideration.

Oct 30, 2017

By Mirko Jurkovic, Thomas Hueper, Jens Kempken

The high competition scenario pushes the steel producers business. Zero defect requirements from customers force the operators for additional efforts in process control and quality management. PQA® has been developed as an advanced process and quality management assurance solution. It is focusing on the analysis of process data, equipment information, inline quality measurement devices and trend analysis. The paper describes the structure of the advanced process and quality management assurance solution PQA®; it gives insights on the expert know-how, process and quality evaluation and points out the benefits like cost reduction, improvement yield and customer satisfaction increase.

Oct 1, 2019

By Liao Jianfeng

The Baosteel Zhanjiang 5,050m3 blast furnaces have been built with highly independent integration and innovation technologies and represented the state of the art of the world’s huge BFs. The proper of BF1 and BF2 is designed with long-campaign technology; both BFs share the same set of stockhouse, water and PCI systems; the BCQS serial-hopper no-bell top, TRT and blower are all local equipment as applied; four top-combustion stoves systems are matched; the BFG is cleaned by fully dry process; and the automation control system for the main process is self integrated. The BFs have been started up and performing with sound indicators. Their smooth proceedings symbolize China’s huge blast furnace ironmaking technology ascending a new high.

Oct 30, 2017

By Franco de Castro Bubani

Cu-base alloys (Cu-Zn-Al, Cu-Al-Be, Cu-Al-Ni), depending on their composition, have martensitic transformations that can be thermally or mechanically induced between a metastable structure called austenite and one or more metastable structures called martensites. In single crystals, depending on the specific composition of the alloy and the crystallographic orientation of the tensile axis, martensite-martensite transformations can be mechanically induced. The hysteresis associated to these martensite-martensite transitions is usually much greater than the one associated to the austenite-martensite transformation. Thus, martensite-martensite transitions are potential candidates for energy dissipation in a mechanical damper. Possible applications that would benefit from high hysteresis include seismic damping devices, dampers for satellites and the aerospace industry, defense and others. We present pseudoelastic cycling results of alloys submitted to different thermal treatments. Our conclusions highlight the fact that, under certain conditions, Cu-base alloys deliver better damping performance than commercially available SMAs and even the new Fe-base SMAs.

Aug 7, 2018

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

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

Oct 1, 2019

By Dr. Steven G. Jansto

The market demand for reduced fuel consumption and CO2 emissions in the automotive, energy and construction sectors have further increased the demand for new and advanced higher quality microalloyed grades produced via TMCP. The technological integration of the process and physical metallurgical advancements of value-added niobium (Nb) microalloyed thermo-mechanical controlled process (TMCP) steels continue to be developed and is an important element for these more demanding end user requirements and cost-effective steel production. The reheat furnace process step has a profound effect on the TMCP performance, final hot rolled steel quality and mechanical property consistency during the production of hot rolled steels. The uniformity of heating applied across the entire width, thickness and length of the slab or billet is essential in the successful achievement of consistent customer properties regardless of the chemistry. The resultant ferrite grain size in the final hot rolled product is significantly governed by the initial prior austenite grain size. However, the transition from laboratory melted and TMCP hot rolled heats to the production scale is often quite challenging. Aberrations in the reheating process step at the industrial furnace are often the root cause of mechanical property quality issues. These combustion process metallurgy parameters connect directly to the resultant TMCP product quality and is defined as Combustion Metallurgy

Oct 1, 2019

By Levi de Oliveira Bueno

Constant stress testing was used for characterization of creep behavior of a 1Cr0.5Mo steel plate in the virgin condition. The tests were performed on creep machines equipped with Andrade-Chalmers type profiles, high sensitivity SLVC transducer extensometry, high stability temperature controllers, and facilities for monitoring the creep curves with an automatic data logging system. Ten creep machines of this type were used in this research, in an experimental work that lasted for one year. Three temperature levels were selected: 538, 565 and 593°C, with stress in the range from 69 to 258 MPa producing rupture times varying from 8 to about 4908 h. The creep curves were all followed with great scrutiny using data logger scanning rates which enabled storing thousands of readings in each case. The experimental analysis involved measurements of minimum creep rate, rupture time and final elongation at rupture. The data were analyzed according to the classical phenomenological / physical relations (Norton, Arrhenius, Zenner-Hollomon, Monkman-Grant) and also considering five traditional parameterization methodologies (Larson-Miller, Orr-Sherby-Dorn, Goldhoff-Sherby, Manson- Haferd and Manson-Succop). Comparisons are presented among the possibilities of data extrapolation from five different methodologies. Comparison is also made with creep results mentioned in literature for the same material in the virgin condition.

Aug 16, 2017

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

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

Oct 1, 2019

By João Luiz do Vale

In standard wear tests, such as pin on disk (ASTM-G99) or block on ring (ASTM-G77), the apparatus simulates conditions that are often different from a machine element real application. Therefore, for an accurate investigation of a tribological application, it is essential to test the real condition in which there are similarities as: geometry, contact details, force application mode, materials, among others. It emphasizes that for studies involving polymeric materials it becomes extremely relevant. Thus, the Laboratory of Surfaces and Contact (LASC) at UTFPR developed an apparatus for sliding bearing on shaft test. In that equipment, loads are applied by a dead-weight system and the frictional force is measured on a load cell. The apparatus operating ranges for load added to the dead weight system and rotation shaft are from 0.2 to 5.0 kgf and from 260 to 3500 rpm, respectively. This paper presents a detailed evaluation of such apparatus, which includes free-body diagrams analysis and a deduction to obtain an equation for the kinetic friction coefficient. Also, the standard measurement uncertainties of a caliper, an electronic scale, and a cell load were determined. It was verified that the kinetic friction coefficient equation is dependent on the apparatus geometry, the applied load, and the frictional force value. Additionally, through the statistical significance analysis it was concluded that some terms in the equation were not significant. Finally, through the application of the error propagation theory in the kinetic friction coefficient equation, the standard measurement uncertainty of the apparatus which showed a value nearby 0.002 along the operating range of the apparatus was obtained.

Jul 31, 2018

By Jose M. Rodriguez-Ibabe, Beatriz Pereda, Beatriz Lopez, Felipe Bastos

The modeling of austenite evolution during the hot rolling of steels is covered in the literature for a wide range of chemical compositions, although mainly for carbon contents below 0.20%. In addition, most research on this topic is oriented for processes that are characteristic of flat products. Compared to those processes, the hot rolling of bars for structural applications presents considerable particularities concerning mainly deformation, rolling speed and rolling temperature profile. Those particularities result in considerable changes on process parameters that affect the austenite microstructure evolution, both in the softening and hardening mechanisms if microalloying elements such as Nb is present. The aim of this work was to develop a model to predict the evolution of austenite microstructure that is suitable for the hot rolling of structural reinforcing bars. Different torsion tests simulating industrial schedules particular from those type of processes were performed. The tests showed the need to investigate Nb strain-induced precipitation interaction with softening mechanisms that can occur during the deformation schedule. At the end, the new proposed kinetics and routines were introduced to a program, MicroSim-Bars®, that is able to model austenite evolution under structural bar hot rolling conditions.

Oct 1, 2019

By Bruce V. Kiefer

A modernization project was undertaken by Kroman Celik Sanayii A.S. in order to improve their product quality, consistency and shape of the coil package, reduce maintenance and delays in rod mill, thereby increasing utilization and productivity. The project involved installation of a new Morgan Intelligent Pinch Roll and High Speed Laying Head, modifications to the existing controlled cooling conveyor, plus replacing the coil reforming station. The new pinch roll and laying head were to provide better control of the ring formation and consistency of the coil on the conveyor, while reducing delays on the conveyor. Changes to the controlled cooling conveyor included installation of new nozzle decks and Optimesh air distribution system along with re-arrangement of existing fans in order to improve both cooling rates and uniformity of cooling. This paper explains details and features of the newly-installed equipment technology. Resulting product and process improvements are presented, including increased tensile strength and uniformity, reduction in delays on the conveyor and reform tub, plus improvements in coil quality.

Oct 30, 2017

By Jens Kempken

A competitive landscape pressurizes the steel producers business, zero defect requirements from customers forces the operators for additional efforts in process control and quality management. The so called quality related cost, which include also rework, cost for downgrading or even scabbing of material is already a remarkable lever in a plants profitability breakdown. The introduction of advanced state of the art grades in the product portfolio requires already a budgeting for the expenses for R&amp;D and quality management. PQA has been developed as a process and quality management software solution next to existing level 2 or level 3 automation systems. It is focusing on the analysis of process data, equipment information, in line quality measurement devices and trend analysis to obtain an answer whether the process is according to definition and expectation and whether the intermediate or final product can be shipped for further processing as prime material. Advanced analytics which are linked to an expert know how based configuration identifies deficiencies in the production and processing process. An intelligent, state of the art quality rating system evaluates tolerable deviations. PQA comprises the software platform including the database, data configurator and collector from the different sources in the production process and units. The core element of the platform is the knowledge based expert know how package defining process and quality determining fundamentals. The paper describes the structure of the software package, it gives insights on the expert know how package, process and quality evaluation and points out the customer benefits, cost reduction, improvement yield, customer satisfaction increase. The link to recent operational references is given.

Oct 30, 2017

By Markus Reifferscheid

Industry 4.0, Digitalization, Internet of Things (IoT) and Cloud Computing are predominant topics in the world economy at the moment. At the ABM week 2017 Dr. Markus Reifferscheid, Head of Research &amp; Development of SMS-group, will talk about the proceeding digitalization in the steel industry with selected examples of SMS-group. He will present advanced concepts and solutions which are currently being developed.

Oct 30, 2017

By Leandro Rigo Ramos, Marcelo Lucas Pereira Machado, Lumena Gloria de Souza Nunes, Mariana Valinhos Barcelos

The aim of this work was to study the influence of temperature on the grain refining process from severe plastic deformations through the simulation of Accumulative Roll Bonding (ARB) by torsion tests. The assays were performed to simulate the ARB at three different temperatures of 550 ° C, 625 ° C and 700 ° C with 5 torsion cycles with equivalent strain of 0.8 per cycle at a rate of 0.1−1 , totalizing an accumulated deformation of 4.0. Grain refining was obtained with an average size of 2μm, 5μm and 6μm for the temperatures of 550 ° C, 625 ° C and 700 ° C respectively. There was a rise in Vickers hardness by 68%, from 119HV in the annealed sample to 175HV in the deformed sample at 550 ° C. In the deformations at 625 ° C and 700 ° C the value of 130HV E and 150HV respectively was obtained. Based on the obtained results, it can be stated that the severe plastic deformations in microliged steel, carried out at temperatures lower than the end of the austenite-ferrite transformation, produce refined grains of the order of 2μm and, consequently, increase the mechanical strength of the material.

Oct 1, 2019

By Luis Acainas Caballero, Karl Hoen, Stephan Krämer, Christoph Klein

The situation of the steel industry is still challenging. Worldwide overcapacities have an impact on profitability. More than ever, the point at SMS group is to provide the steel industry with flexible and profitable technologies and systems over the whole process chain. One example for that is the thin slab casting and rolling technology and, in particular the CSP® technology (Compact Strip Production), being well established for hot coil production. From its introduction in 1989, CSP® technology has been continuously further developed. Today, on a CSP® plant, the full range of high-quality steel grades can be produced with tightest geometrical and metallurgical tolerances under optimal economic conditions. With the introduction of semi-endless rolling and, as a further step, the endless rolling process, the product range for thin and ultra-thin products has been further enlarged, allowing for the production of hot rolled coils with a thickness of 0.8 mm for low carbon steel grades. Also high-strength steel grades may be produced with gauges below the minimum product thickness that can be achieved in a conventional-type hot rolling mill. Another step in the further development of CSP® technology is digitalization. In December 2016, the CSP® plant of Big River Steel (BRS), located in Arkansas, USA was put into operation. It is the first learning steel mill in the world. The CSP® plant of BRS comes with innovative technologies, providing impressive operational results right from the beginning.

Oct 1, 2019

By Johan PEERS, François DUMORTIER

Today, solutions to optimize Capital Expenditure (CAPEX) & Operational Expenditure (OPEX) for small capacity Cold Rolling Mills (CRM) as well as for high capacity CRM are available, as extensively described by various Original Equipment Manufacturers (OEMs) & steel makers. A suitable solution for small capacity CRM is to start with a single stand reversing mill (up to 400 ktpy, depending on product mix), which can then be expanded into a twin stand mill (up to 900 ktpy, depending on product mix). The main drawbacks in conventional practice are the off-gauge length in single stand set-up and the long downtime of the mill during the erection of the second stand. For higher productions CRM, it is common practice to directly select a new Pickling Line Tandem Cold Mill (PLTCM), with a high CAPEX. Is there an in-between solution that would allow to start with limited output and CAPEX, without jeopardizing the ultimate expansion goal (1.2 to 2 mtpy), for which PLTCM is the best techno-economical choice? In the absence of a solution, JOHN COCKERILL developed an integrated solution that limits the CAPEX in the first phase of development, without crippling affecting future endeavors through an easy and economically sustainable expansion into a PLTCM, without long production downtime. The solution consists of first installing a twin stand mill, expandable into a tandem mill thanks to a smart design of the line. It is therefore possible to limit the production to 900 ktpy in the first phase of the project and then convert the mill into PLTCM in the second phase to increase the production from 1.2 to 2 mtpy, depending on the market trends and financial capabilities. In summary, JOHN COCKERILL has developed a smart new layout in reversing phase combined with a brand new rolling strategy to optimize productivity and limit off-gauge, compared to conventional solutions (patents pending). In addition the layout enables an easy conversion to tandem mill without high over investments, which is more sustainable financially than the initial purchase of a PLTCM. Long downtimes to allow for capacity extension, detrimental to this phase-by-phase approach, are also avoided. Technical and process description of the new layouts and rolling strategies, together with CAPEX & OPEX descriptions of the phases are detailed in this paper.

Oct 1, 2019

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 Hongshuang Di, Tianyu Zhang, Huiqiang Huang

A CMnSiAl transformation induced plasticity (TRIP) steel was used to study the effect of retained austenite on room-temperature mechanical properties. The steel plates with retained austenite were obtained by hot rolling, cold rolling and subsequent continuous annealing. The starting and finishing temperature of hot rolling are between Ac1 and Ac3. Reduction ratio of cold rolling is 75%. The continuous annealing is carried out at different intercritical temperatures. The relationship between work hardening exponent and retained austenite was discussed. The results show that, the Ac1 and Ac3 were much high because of the alloy elements, and the temperature range between them was wide. Due to the high hot rolling temperature, the grains was hereditarily refined as a result of dynamic recrystallization. Annealing at intercritical temperature of 930 ºC, retained austenite with relatively high stability reached a maximum volume fraction of 25%, a maximum total elongation of 30.2% and a best ultimate tensile strength × total elongation of 20.1 GPa·%. Instantaneous work hardening exponent reflects strengthening mechanisms at different strain stages. The TRIP effect of retained austenite is the main mechanism during deformation. With retained austenite of sufficient amount and high stability, continuous work hardening was observed in the tensile specimen of 930 ºC.

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 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