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By Enrique Francisco Somolinos Garcia-Morales

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

Aug 1, 2018

By Jose Maria Rodriguez-Ibabe, Ronaldo Antonio Neves Marques Barbosa, Douglas Glenn Stalheim

Major costs in the production of both flat and long commodity grade structural steel products include alloy, labor and energy. Flat and long commodity grade structural steels such as ASTM A36, ASTM A527Gr50, S235, S275, S355 and other equivalent world societal standards represent over 500 million annual tons worldwide. These simple commodity grades consist of a minimum of three base common alloying elements, carbon, manganese, silicon and then can be supplemented with microalloying elements of either vanadium or niobium. Since 2016 raw material costs for two of the five alloying elements in these commodity grade structural steels, FeMn and FeV, have risen significantly and/or have become volatile making it difficult to maintain stability in profitability for these commodity grades. For steel plants producing hundreds of thousands and in some cases over a million tons annually of these common structural steel grades because of the significant alloy cost increase for Mn and V alloy additions has squeezed profitability of these grades. These grades typically represent the base loading for cost controls in most all steel plants and hence a significant cost increase or volatility in two of the five elements used for these grades having a negative effect on overall production costs. However, with a proper strategy for alloy designs working in conjunction with the mills existing processing capabilities to achieve the desired end metallurgy/mechanical properties, alloy costs and operational efficiencies can be realized.

Oct 1, 2019

By Edo Engel

Whereas only a handful of decades ago, typical blast furnace working volumes were below 1000 m³, such furnaces are currently designated compact or even mini blast furnaces. For certain business cases, however, small furnace sizes remain an attractive option. Decades ago, this size blast furnace would have produced a maximum of 0.3 Mtpa with its 600 m³ working volume over a campaign of up to four years. The current state of technology and operational know–how will allow a similarly sized furnace to produce over 0.7 Mtpa while achieving the multiple decade campaigns that have become familiar to steel producers in full sized operations. This level of productivity, but especially the reliability and supply security associated with mature technology, allows for integration into minimills or taking a first step towards a full scale BF–BOF integrated mill. Steel producers considering such scenarios, which are typically attractive for emerging economies, are confronted with fundamental decisions, one of which is for the technological basis for the compact or mini blast furnace to be included in the plant. This article addresses some of these decisions from an operations–based perspective. A small number of case studies is included.

Aug 16, 2017

By Andrelio Marcos Ribeiro, Lucio Ribeiro Camisao, Antonio Carlos Ataíde, Alan de Sousa Pereira, Renato Siqueira Campos

The annealing and pickling line n. 1, responsible for the production of stainless steel 3xx, 4xx and 430a in thicknesses from 4 to 0.4 mm, has two vertical strip accumulators. These are intended not to let the material exceed the determined time in the furnace and in the pickling, and consequently do not cause defects like burning and excessive pickling. Strip accumulator n. 1 avoids the line from stopping during welding execution of the coils in the welding machine. In sequence, the strip accumulator n. 2 avoids the line from stopping at the end cutting of the tips, and in the coils removal from the pickling. The strip accumulators have a roller table that during the strip accumulation moves vertically downwards while its counterweight moves vertically upwards, and do the inverse movement when the material is released. On December 12th 2018, the failure occurred in the strip accumulator n. 1, where it was verified that the shaft of one of the pulleys had been fractured by high-cycle mechanical fatigue, which was characterized by alternating bending. With the fracture of the shaft, occurred the unevenness of the counterweight that damaged the guides. Failure analysis of this occurrence was based on the PDCA methodology, when was verified a weld between the shaft and the pulley. The analysis of the microstructure transformation in the molten zone, in the heat affected zone and in the base metal was carried out in an optical microscope, and no abnormality was observed. It was also carried out the end test by penetrating liquid, finding an inadequate weld in its geometry, as well as longitudinal trunks along the center of the weld bead. However, after a huge investigation of the causes, it was found that the failure was triggered by an inadequate design of the pulley shaft. It was also verified that the shaft had an open measure, inadequate for the operational context. After the analysis, action plans were drawn up based on the FMEA methodology to inhibit the failure recurrence.

Oct 7, 2019

By Ivan César Lopes Diniz, César Romero Afonso Goulart Júnior

Mandrels are tools applied to manufacturing seamless tubes. In VSB plants (Vallourec Soluções Tubulares do Brasil), it is used in two mills. Mandrel and PQF Mills. This is an expensive tool due its alloy (hot work tool steel – AISI H13) and lengh (between 12 meters and 22,5 meters). An opportunity to apply mandrels from PQF in Mandrel Mill has been identified. However, mechanical properties of PQF mandrels must be improved. This work presents the heat treatment process of Quenching and Tempering developed internally at VSB to improve PQF mandrel properties aiming to achieve Mandrel Mill requirements. Hardness and metallography tests were performed before and after some steps of the heat treatment to characterize and validate the process.

Oct 5, 2019

By Kermit Reins

The most recent modernization phase of the wire rod mill at Sterling Steel involved installation of a pre-finishing mill, using a Morgan Vee Mini-Block, a new water box and shear with utility systems and automation. The new mill configuration adds more stands to the mill for better drafting and is designed to improve finished product quality by providing a more uniform entry temperature, better control of the feed section into the No-Twist® mill as well as enhanced surface quality. The new shear improves cut length accuracy as well as decreases the amount of trimming to reduce yield loss. This paper explains the changes made in the mill and the features of the new equipment and automation.

Aug 17, 2017

By Thomas Germershausen

Worldwide BOF-based steel plants are faced with demanding environmental requests and rising energy costs. For cleaning of primary gases from the BOF the scrubbing technology is worldwide adapted. For wet-scrubbers there is a direct relation between pressure loss and achievable clean gas dust content. Subsequently main energy consumers within Gas Cleaning Plants are the driving fans. To evaluate actual performance and to identify optimization measures extensive field measurements at existing Gas Cleaning Plants were performed. The operational results from various BOF plants worldwide will be presented and benchmarked. As a conclusion, advanced control strategies for reduced energy consumption and lower environmental impact were developed and implemented.

Jul 30, 2018

By Detlef Ehlert

Flexibility in terms of producing high sophisticated products with an exceptional wide range of properties and dimensions requires physical based process models for the generation of optimal set points. Therefore SMS applies since many years an integrated PSC® (pass schedule model), PCFC® (profile, contour and flatness model) and CSC (cooling section control) for the use in hot strip mills, CSP® plants and plate mills offering best possible product tolerances. Focus during the development of the model was made on the best possible physical description of the rolling process to minimize the need of complex adaptation algorithms. As an addition SMS has also developed a microstructure model to ensure the quality control with respect to mechanical properties and to save up the needs of taking samples. Beside of this the modular design of the Microstructure and Material Property Model (MPM) offers additional benefits to improve the accuracy of the other models, e. g. the recrystallization model in the finishing mill. Using the results of that model strain hardening or softening effects during rolling can be predicted and an optimum pass schedule can be calculated to avoid rolling stability problems related to phase transformation.

Aug 16, 2017

By Andrea Taurino

Innovation means implementing a new product or a product that has undergone significant improvement over time, in terms of method, form and performance. Innovation encompasses all the scientific, technological, organizational, financial and commercial steps that need to be taken to put it into operation. Innovation combined with research and development makes it possible to perfect the product with consistency over time. Taking inspiration from the bases developed by the Austrian economist Joseph A. Schumpeter back in 1911, Danieli came up with the concept of “Innovaction” – a combination of Innovation and Action, to refer to the development and advancement of various products for the steelmaking industry, including the loop laying head for wire rod.

Aug 17, 2017

By Michel Rodrigo Luiz, Glaucio Augusto Polini, Giardini F. Lazzarin

ArcelorMittal's pickling and cold rolling line has been demanded to increase production since the installation of equipments in 2015. In addition to the improvement in productivity related to these new equipment, one of them the automatic surface inspection system (SIAS), work has also been developed in other equipment seeking improvement of production indicators. The present article exposes the actions and gains that were achieved with actions on two equipments in the same section as the Side Trimmer. The first one deals with the optimization of time gains with sequencing adjustments without financial contribution, using only internal labor seeking reduction of unproductive times by adjustments of the side trimmer in the cold strip mill. The second item discussed demonstrates the actions and the gains generated due to the availability of new resources (installation of SIAS equipment), the optimization of these resources seeking a focus on the reduction of ruptures in the tandem cold mill, configuring the same in the aid of the identification of critical defects and also in the automatic speed reduction action of the tandem cold mill in defects considered serious. In both cases the intention was to improve production, seeking to improve the results of the section and the line.

Oct 1, 2019

By Javier Martinez Rubio

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

Aug 16, 2017

By José Aparecido Pereira

The innovative methodology developed by the author allows the elaboration of an Angle Roll Pass Design based on the practical observations of the rolling process and applies mathematical criteria, using the Ekelund´s formula supported by Advanced Excel tools (Reach Goal, PROCV-PROCH, Macros) and AutoCad. The first step is the definition of the number of stands, roll dimensions, gear boxes reduction, initial stock, average reductions, spread factors, finishing speed and type of grooves. For each pass are calculated: bite angle, spread, section reduction, lost and gain of temperature, separating force, speed, torque and motor power. After these calculations and checking of the parameters, the program calculates the dimensions of the passes transforming the flat passes into shaped ones. With these dimensions it is possible to draw the grooves using AutoCad and check section reductions. This methodology was already used for the development of a new project and also to check the parameters of existing ones, with comparison of the results and has shown to be reliable in real and tested projects. It is an innovative process that is not available in known literature.

Oct 1, 2019

By Simon Chiartano

A global reflection on the design of blast furnace main runner was investigated in this paper. TRB Company used its skills and expertise to understand what the best option for this sensitive component is, including some innovative tools: intelligent block design for safety lining, thermal & thermomechanical numerical simulation, immersive measurement by thermocouples, IR thermal camera, 3D laser scanner.

Oct 1, 2019

By Ernst Lindemann

The SMS group has developed the ultrasound technology “HD scan” for inspection of the internal quality of as-cast products. This method of sample analysis requires less preparation work and is safer than the current, most common technique of etching and/or sulphur printing. Furthermore, this technology offers a three-dimensional view into the sample of the cast product and thus more representative information for a better quality evaluation. The internal quality evaluation can be performed automatically and objectively by software based on clear statistical methods. A quantitative centerline segregation rating can be assigned to each sample, based on the size and distribution of segregates detected by the unit. Internal crack statistic (length, position, orientation, etc.) and narrow side profile can also be measured. Grain macrostructure can also be visualized which allows for a potential optimization of casting parameters like strand cooling, soft reduction or electromagnetic stirring. The accuracy of the new method was proven by parallel metallographic investigations of more than 100 samples of different steel grades and sample shapes. Automatic defect evaluation and classification was compared against macroetching results. It was found that HD scan identified more defects and the visualization of the macro structure could be performed in more cases than with macro etching. All tests, comparisons, further developments and analyses for various steel producers and steel treatment companies have been conducted at the HD scan unit, located at the SMS group headquarters in Düsseldorf, Germany (Figure 1). Based on the results, SMS group has designed a unit which can be used in industrial scale.

Aug 17, 2017

By Ernst Lindemann

Steel suppliers are required to deliver sheets with particular qualities and with lightweight-potential to the automotive industry. New types of steel call for new production processes. SMS group has developed a new micro-mill-concept, the core of which is the belt caster. This was first built on an industrial scale and has been put into operation and developed together with Salzgitter Flachstahl GmbH. The robustness in industrial-scale operation could be verified. The full use of the belt casting technology, mainly related to energy efficiency and CO2 reduction, is realized with the micro-mill-concept. This is an in-line-process, casting and rolling in one line.

Aug 17, 2017

By Francisco Morganti

Weight reduction is the main target of all carmakers, which results in a continuous development of new steel grades. Latest 3rdgeneration advanced high-strength steel grades (AHSS) are complex materials with special chemical compositions and multiphase microstructures. The pickling, annealing and galvanizing processes of these grades aresomewhatdifferent due to the changed chemical compositions and microstructures. Therefore, these innovative steel grades place new demands on the plant technology of pickling, annealing and galvanizing lines. The most significant challenges for the pickling process are sludge occurrence during pickling, varying pickling times, weld ability of the materials, changed visual appearance and required high surface qualities. The most important topic concerning annealing line is a precisely controlled and very flexible heating and cooling process in the furnace.One of the new requirements in galvanizing linesis the prevention of surface faults caused by bare spots, which can occur since these materials feature a higher content of alloying elements like silicon or manganese. Prevention is possible with the special pre-oxidation technologies.Due to the higher strength of the material also the mechanical equipment has to be designed differently in these lines. This paper describes the influences of the changed chemical composition and material characteristics of modern steel grades on the pickling, annealing and galvanizing process and gives an overview about the technical solutions.

Oct 30, 2017

By Andrew Slifka, Pello Uranga, Douglas Glenn Stalheim

Structural steel final mechanical properties of strength and ductility are predominately generated by the final ferrite grain size/packet size and homogeneity of that ferrite grain size/packet size through the cross-sectional area. Forty to seventy percent of the strength components come from how fine the final cross-sectional ferrite grain size/packet size that can be produced.[1] All the ductility properties of structural steels for a given microstructure are predominately driven by how fine AND homogenous the final cross-sectional ferrite grain size/packet size can be refined.[2,3,4] One key ductility property of structural steels used in construction and energy transmission applications is fatigue. Both low and high cycle fatigue can be realized in these end applications, however, low cycle fatigue is typically the predominate mechanism. In construction applications the environment for fatigue is typically air, such as in wind towers or high-rise building construction. In energy applications, there is an interest in high pressure (5.5 – 21 MPa, 800-3000 psi) gaseous hydrogen as an alternative fuel source to fossil fuels. A project to study the effect of the cross-sectional grain size/homogeneity of a relatively pure polygonal ferrite microstructure on the fatigue performance in air and high-pressure gaseous hydrogen has been developed. This paper will discuss the project strategy, microstructure developed for the project and initial test results.

Oct 1, 2019

By Martin Dirks

Nowadays the sinter cooler often becomes the bottleneck of the sinter production, with outdated equipment leading to low productivity and high operation and maintenance costs. Furthermore valuable energy is simply destroyed in the cooler, which is not compatible anymore with a cost efficient and environmentally friendly sinter production. Paul Wurth has developed and improved two types of coolers, the annular cooler and the shaft cooler which offer flexible solutions to the specific situation of each client. The classic design of the annular cooler was completely revised and is now composed of a rigid ringframe construction as opposed to the traditional design with individual sintering cars, avoiding the typical problems of centering. Additional features of the PW annular cooler are the low air leakage rate and the increased effective cooling surface due to the removal of dead areas. This leads, in addition to the lower weight, to lower operating costs and a smaller space requirement. The shaft cooler stands out with an even smaller space requirement and a lower sinter outlet temperature because of a very long residence time of the sinter inside the shaft. Its development into a pure counter flow cooler aims at maximizing its energy efficiency, as it is designed as a system with a very low demand for cooling air, high air discharge temperatures and highly reduced dust emissions. For both cooler types flexible heat recovery solutions can be offered. These solutions include the supply of hot combustion air to the ignition hood burners and the sinter strand, the production of steam for the clients steam grid or the production of electric energy.

Aug 16, 2017

By Sander Mul, Michael Brandner, Armin Paar

Graphitic HSS roll grades such as ESW’s brand VANIMO can be considered as the latest developments for the last finishing stands in hot strip mills. These roll grades are developed on the basis of the alloying concept of (Carbide Enhanced) Indefinite Chill work roll materials. During the development of VANIMO, the amounts and types of carbide forming elements were increased and adjusted into the direction of cast HSS roll grades. The microstructure of graphitic HSS roll grades therefore consists of tempered martensite, cementite and several different carbide types as well as a well-defined amount of free graphite. The main purpose of graphitic HSS roll grades is to combine the high surface quality of Indefinite Chill alloys as well as the high wear resistance of HSS roll grades. Several systematic steps were taken to increase the wear performance from Carbide-Enhanced Indefinite Chill grades to the more advanced VANIC grade and further on to the highest alloyed roll grade VANIMO. In every development step, the surface quality of the roll grades was carefully monitored. The decision to invest in new testing equipment at ESW’s plant was driven by the wish to see microstructural effects of different alloys in a macroscopic dimension. Usually samples are taken from cast rolls and investigation is done in comparably small areas compared to the total surface of a roll. Rolling of strip is done with the entire barrel, so effects of alloy and microstructure can appear anywhere on the barrel surface. To ensure better understanding and deeper knowledge about influences of alloying trials we decided to install the last version of LRI (Lismar Roll Inspection). LRI includes the latest technology of Eddy Current with an enormous resolution. Depending on the formation of carbide precipitations, carbide network as well as matrix and free graphite, the EC test can detect smallest differences. The possibility to analyze the different results of EC and UT surface wave inspection will be discussed. A few examples of surface effects in the mill application will be discussed and improvement strategies explained.

Oct 1, 2019

By Zhisong Chai, Wei Xu

Q&P steels undergo continuous multiple processes, including hot rolling, intermediate heat treatment, cold rolling and continuous annealing etc. The inheritant effect of initial microstructure could affect the final microstructure and mechanical properties of Q&P steels. In this work, effects of different hot rolled microstructure/texture on the final microstructure and properties subjected to Q&P process were investigated in Fe-0.38C-1.58Mn-1.6Si system. Different initial microstructures were generated combing different TMCP and cooling strategies. The microstructure and texture of hot rolled materials were characterized in detail. The hot rolled material was subsequently processed by intermediate annealing, cold rolling and continuous annealing. The comparison reveals great effects of the initial hot rolled microstructures, i.e. inheritance effect. The faster reverse transformation would lead to more sufficient austenitization and it would greatly weaken the inheritant effect of the initial microstructure. Although the difference of final phase fraction for different initial microstructures was not significant, the inheritance effect was mainly reflected in the effect on austenite morphology. For the mechanical properties, no obvious difference in strength was shown for the samples with different initial microstructures after Q&P heat treatment, but there was fluctuation in elongation.

Oct 1, 2019