Rolling Research Papers - Academia.edu (original) (raw)

It is the objective of this article to investigate the influence of surface preparation on the cold roll bonding (CRB) process. In this context, the effects of surface preparation parameters consisting of surface preparation method, surface roughness, scratch-brushing parameters, and the delay time between surface preparation and rolling are investigated on the bond strength of aluminum strips. The bond strength of two adjacent aluminum strips produced by the CRB process is evaluated by the peeling test. Furthermore, the interface region is investigated by metallographic observations. Our findings indicate that higher surface roughness values and shorter delay times improve the bond strength. It is also found that degreasing followed by scratch-brushing yield the best bonding properties.

- by
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- Materials Engineering, Surface Roughness, Time-Delay Systems, Mechanical Testing

The exoskeleton of the lobster Homarus americanus is a multiphase biological composite material which consists of an organic matrix (crystalline α-chitin fibers and various types of non-crystalline proteins) and minerals (mainly calcite). In this study we discuss experimental data about the mesoscopic structure and the crystallographic texture (orientation distribution) of the α-chitin–protein fiber network in this material. The synchrotron measurements reveal very strong crystallographic textures of the α-chitin. According to these data, a large fraction of the α-chitin lattice cells is arranged with their longest axis parallel to the normal of the surface of the exoskeleton. Additionally, a smaller fraction of the α-chitin cells is oriented with their longest axis perpendicular to the cuticle surface. These structural investigations reveal the pronounced role of crystallographic orientation distributions in mineralized biological composite materials which may be of relevance for an improved understanding of biological and bio-inspired nano-composites.

- by Dierk Raabe
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- Materials Engineering, Mechanical Engineering, Materials Science, Crystallography

UDC 621.771 Determination of real boundary cooling conditions is a fundamental requirement for numerical models and simulations to optimize and control selected processes in metallurgy. To obtain these boundary conditions, a special method has been developed. The input temperature history of cooling is obtained from experiments. The measured data are then mathematically evaluated. Realistic boundary conditions, as the heat transfer coefficient between hot surface and the coolant, allow optimization of the cooling sections and the design of their configurations. To realize the cooling test, unique laboratory equipment was developed. It allows setting of cooling conditions close to the plant conditions. The paper presents examples of optimization of work roll cooling, examples of design of sections for in-line heat treatment of metals and procedure for designing new high-pressure descaling sections. The methodology proposed by the Heat Transfer and Fluid Flow Laboratory of the Brno University of Technology is typically used to determine the heat-transfer coefficient on the surface of high-temperature material in the applications of heat treatment, cooling of rolls of hot rolling mills, and high-pressure descaling. The methodology enables identifying the effect of nozzle water jets on the heat-transfer coefficient or on removal of high-temperature scale and leads to cooling and descaling optimization for industrial partners.

- by Petr Kotrbacek
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- Energy, Optimization, Iron Oxide, Cooling

The competitive scenario of steel industry requires studies and developments to improve manufacturing processes focusing on increasing productivity and reducing costs. The practice of coating rolls for cold rolling with the chrome aims to increase the rolling campaign, reducing their wear by increasing the surface hardness, which guarantees a greater homogeneity in the surface of the rolled products. The present paper presents a study on the effect of the chromium coat on a forged steel rolls on the wettability of a SkinPass solution. The hardness of the coated layer and the contact angle were measured for two concentrations of solution on two types of surfaces, comparing the coated and uncoated surfaces. The results show that there is an influence of the coating on the wettability of the fluid when comparison are made with chrome coated and uncoated materials, being verified through tests in Goniometer. The productivity of the coated rolls showed higher productivity than the uncoated ones.

- by Karl Kristian Bagger
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- Surface Engineering, Surface Roughness, Surface Coatings, Wettability

An overview is represented of the methods and hardware which applied for angular backlashes measurements in the different branches of industry. The advantages and shortcomings have shown for different principles of direct wear measurement in the tooth couplings, spindles and gearboxes of the rolling mills drive trains. The description is represented of the digital devices which are designed in the ISI for angular backlashes measurement and which can work in the embedded monitoring system with the wear diagnostics function.

- by Pavlo Krot
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- Machine Fault Diagnostics, Rolling, Wear Measurement, Drivetrain Dynamics

Flat rolling basically involves pushing a metal work piece into the gap between two rotating rolls which then simultaneously draw the work piece into the rolls and compress it to reduce the thickness and increase the length. The primal target of the experiment is to make a roll pass design for hot flat rolling. Roll pass design methods includes determining the dimensions, shape, number and type of arrangement of rolling mill passes. Necessary calculations are done to determine rolling load, torque and power by using the data. This experiment also acquaints us with different types of roll passes like diamond pass, box pass, round pass, oval pass by using neat sketches and solidworks drawing software.

- by Tariq Islam
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- Mechanical Engineering, Rolling

The aim of this work has been to develop an automatic roll pass design method, capable of minimizing the number of roll passes. The adoption of artificial intelligence technologies, particularly expert systems, and a hybrid model for the surface profile evaluation of rolled bars, has allowed us to model the search for the minimal sequence with a tree path search. This approach permitted a geometrical optimization of roll passes while allowing automation of the roll pass design process. Moreover, the heuristic nature of the inferential engine contributes a great deal toward reducing search time, thus allowing such a system to be employed for industrial purposes. Finally, this new approach was compared with other recently developed automatic systems to validate and measure possible improvements among them.

- by Antonio Langella and +1
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- Hot Rolling Processes, Hot Rolling, Rolling, Hot and Cold Rolling

RESUMEN El proceso de elaboración de harina precocida esta conformado por múltiples etapas, una de ellas corresponde a la laminación del grano de maíz en estado de cocción, por medio de rodillos. Para estimar las fuerzas que se generan durante el aplastamiento, es necesario analizar la interacción entre los granos y los rodillos, tanto desde el punto de vista geométrico como desde la perspectiva de la naturaleza de los materiales involucrados. Con este objetivo en mente, se han propuesto dos experimentos muy sencillos de implementar. El primero, para determinar el coeficiente de roce dinámico entre el maíz y el acero del que están elaborados los rodillos. El segundo, para estimar la fuerza necesaria para el aplastamiento de los granos de maíz ya cocinados. Estos dos parámetros son la base para emprender los cálculos involucrados en el diseño del laminador. Se describen con detalle la aplicación de los experimentos propuestos y sus resultados. ABSTRACT The process of production of pre-cooked flour is shaped by multiple stages, one of them corresponds to the lamination of the grain of corn already boiled, by means of rollers. To estimate the forces generated during the crushing, it is necessary to analyze the interaction between the grains and the rollers, from the geometric point of view as well as from the perspective of the nature of the involved materials. With this aim in mind, it has been proposed two simple experiments very easy to implement. The first one, to determine the dynamic friction coefficient between the corn and the steel from the rollers. The second one, to estimate the force necessary for the crushing of the grains. These two parameters are the base to undertake all the calculations involved in the design of the rolling mill. The application of the proposed experiments and their results are described with detail. INTRODUCCIÓN La harina de maíz precocida es un producto ampliamente utilizado en la sociedad moderna (sobre todo en Latinoamérica) por sus múltiples beneficios en cuanto a conservación, transporte y versatilidad en la preparación de una variada gama de platos. Desde la recolección del grano en campo hasta la presentación final, intervienen en su preparación varios procesos, tales como:

- by Pedro Viggiani
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- Rolling

En este trabajo se discuten algunos defectos superficiales típicos de los productos largos de aceros al carbono, tales como alambrón y barras lisas y nervadas, a los efectos de mostrar algunas técnicas metalográficas que ayudan a definir la etapa del proceso en la que se formó el defecto, la localización original del defecto si ya existía como tal en la palanquilla, etc. Conocer el origen de los defectos, trae aparejado la posibilidad de implementar las correcciones necesarias en los procesos con el propósito de eliminarlos y mejorar la calidad del producto. Se revisan defectos superficiales tales como grietas, escamas, pliegues, marcas y rozaduras. En cada caso, se discute los rasgos que se pueden observar mediante microscopía óptica, sobre cortes pulidos sin ataque o bajo ataque con Nital, cromato sódico alcalino, reactivo de Oberhoffer, etc.

- by Jorge Madias and +1
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- Metallography, Steel, Defects, Hot Rolling

Ultrafine grained steels with grain sizes below about 1 m offer the prospect of high strength and high toughness with traditional steel compositions. These materials are currently the subject of extensive research efforts worldwide. Ultrafine grained steels can be produced either by advanced thermomechanical processes or by severe plastic deformation strategies. Both approaches are suited to produce submicron grain structures with attractive mechanical properties. This overview describes the various techniques to fabricate ultrafine grained bcc steels, the corresponding microstructures, and the resulting spectrum of mechanical properties.

- by Dierk Raabe
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- Materials Engineering, Mechanical Engineering, Materials Science, Crystallography

In recent years the Steel Rolling Mills have undergone a significant change regarding quality requirements, productivity and the thickness of the products being rolled. The Hot Strip Mills have emerged with higher productivity, excellent surface finish of coils with thinner gauge rolling. Stringent dimensional tolerance, strip finish and profile flatness requirements and higher mill productivity have called for improved wear resistance and fatigue crack resistance of the rolls used in the finishing stands. For the finishing stands of hot strip mills Duplex ICDP and ICDP-EC rolls are nowadays produced through either Vertical Centrifugal Casting (VCC) or Horizontal Centrifugal Casting (HCC) process. These duplex rolls generally consist of a Shell made of alloy cast iron and the Core made of spheroidal graphitic Iron. It has been observed that the Performance of the imported ICDP-EC Rolls manufactured by the Market leaders far superseded the Performance of the indigenous rolls due to higher wear and fatigue crack resistance of the imported rolls. Use of the imported rolls also improved the surface quality of products rolled and improved the campaign life of the rolls. A study of few Imported and Indigenous rolls was carried out to find out the deficiencies of the Indigenous Rolls in comparison to the Imported Rolls manufactured by the market leaders. In this paper the chemical compositions and microstructure of the imported rolls have been benchmarked with those of the indigenous rolls. The morphology and content of

- by Mausumi Kar
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- Casting, Forging, Melting, Rolling

In this paper, micro-structural, mechanical and tribological behaviors of roll materials i.e. high speed steel (HSS), high chromium iron (HiCr), indefinite chill irons (IC) and other have been reviewed. The technological process of the rolling consists of many factors that influencing the fatigue life of rolls like rolling temperature, roll groove design, rolling speed and turning due to wearing. These parameters are analyzed to advance maximum fatigue life of the rolls as well as to shrink overall energy consumption, increase production and decrease overall costs. Finite element analysis of adamite roll is carried out by applying process parameters and variables at high temperature those are responsible for roll wear. According to appropriate chemical properties, microstructure and mechanical property some new wear-resistant roll grades for conventional hot rolling process is suggested.

- by Laukik P Raut
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- Rolling

Because of the large volume of manufactured sets, hypoid gears are usually hard finished after heat treatment using the lapping process. In the lapping process, a gear set is run at varying operating positions and under a light load in... more

- by Qimi Jiang and +1
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- Mechanical Engineering, Modeling, Wear, Tribology
- by Ahmed Saleh
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- Neutron Diffraction, Texture, Recrystallization, X ray diffraction

It is considered the results of experimental research of the rolls surface periodic defects (chatter marks) which appear during grinding. A new method of diagnostics was tested for the defects which were not recognized visually and a procedure of its implementation was developed. Vibrations measurements were carried out during full cycle of backup roll treatment. It was carried out spectrum analysis of the vibration signals and the ways to avoid defects proposed.

In the shape rolling process, the reduction of the number of passes is a challenging topic for the steel industry. This can be achieved by enhancing the design approach or by developing new rolling passes that allow the production of high cross-section reductions such as with the slit roll pass.
However, in order to design a robust roll pass, the lateral spread of the workpiece must be predicted correctly to prevent incomplete, or even worse, excessive roll groove fulfilling (which may cause roll damage).
In the present investigation, the possibility of using a finite element model to predict the lateral spread in a slit roll pass is investigated. The results of the finite element model are then used to adapt and calibrate two analytical models that were developed originally for strip rolling and shape rolling with concave grooves.

- by F. Lambiase
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- Rolling of Metals, Hot Rolling Processes, Hot Rolling, Rolling

We wished to determine the trajectory of a point on the circumference, rather in our case, the surface, of a rolling sphere, on a horizontal plane, and thereby simulate it. During rolling, the point of contact between the sphere and the surface will be at instantaneous rest. By setting up equations of motion and using Newton’s force and torque expressions and using the rolling condition, we obtained the trajectory of our point, which is a cycloid. By running a program in python, we were able to determine the co-ordinates of our point at any instant of time. We managed to run the simulation on Visual Python. The same problem was then extended to a sphere rolling down an inclined plane and we once again obtained the trajectory of our point as a cycloid.

- by Rohit S Chandramouli and +1
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- Mathematical Physics, Physics, Theoretical Physics, Computational Physics

The paper deals with flatness defects prediction in thin plates which appear during rolling. Their origin is the roll stack thermo-elastic deformation. The combination of the elastic deflection, the thermal crown and the roll grinding crown results in a non-parallel bite. If the transverse roll profile is not an affinity of the incoming strip profile, differential elongation results and induces high stresses in the outgoing strip. The latter combine with the imposed strip tension force, resulting in a net post-bite stress field which may be sufficiently compressive locally to promote buckling. A variety of non-developable shapes may result, generally occurring as waviness, and classified as flatness defects (center waves, wavy edges, quarterbuckles…). The purpose of the present paper is to present a coupled approach, following [1] : a simple buckling criterion is introduced in the FEM model of strip and roll deformation, LAM3 / TEC3 [2]. The postbite stress field is in much better agreement with experiments if this treatment is used, as will be demonstrated.

- by P. Buessler and +1
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- Stress field, Residual Stresses, Buckling, Sheet Metal

STUDI KASUS CACAT PRODUKSI BAJA LAPIS SENG DAN CARA PENCEGAHANNYA PADA PROSES COLOR LINE

- by Indra Aryz
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- Rolling

Wear modelling is one of the greatest issues for wear fault monitoring and it belongs to condition-based maintenance practices. The early prediction of the fault might provide a more cost effective way for maintenance. It might have the potential to actively influence the design procedures of materials and tribology contact. However, it is the core to gain better understanding of the deterioration process and to achieve better use of Predictive Health Monitoring (PHM) procedures. There are a number of dynamic analyses of spalled components, single-wear prediction models and integrated models considering dynamic analysis and wear predictions. However, rolling element bearing requires more sophisticated models to study wear fault taking into account multi-wear mechanisms and the sliding rolling impact phenomenon. The paper starts with a review of the main contribution within wear prediction modelling and system dynamic analysis. Based on the relevant contributions, a numerical dynamic wear analysis for rolling element bearing is proposed. In the paper, a comparative study was performed based on the empirical findings of real rolling bearing applications and the collected modelling contributions. The paper highlights a number of practical considerations that are needed to be modelled within the whole integrated prediction of wear process. Moreover, the integrated analysis model relies highly on the incremental feedback relationship between basic modules. A wear modelling tool has potential to provide more accurate wear prediction and better support for diagnosis and prognosis purposes. This might lead to reduction of the overall operational losses and their associated costs once it is accurate.

- by Idriss El-Thalji
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- Engineering, Mechanical Engineering, Modelling, Wear

The effect of the addition of Cr on tensile properties in high Co–Ni secondary hardening steels containing W has been seen in as-quenched and aged conditions. Two kinds of Co–Ni steels, containing only W (W steel), and W and Cr (WCr steel), were severely multipass-rolled in the unrecrystallized region, followed by direct quenching. Both steels showed secondary hardening peaks with precipitation of fine M2C carbides during aging. The secondary hardening reaction was promoted by the Cr addition although there was some decrease in tensile strength. In terms of tensile behavior, it is pointed out that both yield strength and yield ratio (YS/UTS) were considerably decreased by the Cr addition. In addition, the tensile strength to hardness ratio is larger in the as-quenched condition compared with the aged condition.

- by Ho Thi Sim
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- Materials Engineering, Mechanical Engineering, Quenching, Hardness

During practical experiments relating to thermomechanical rolling of steel bars on continuous fine section mill of Trinec Steelworks, non-homogenity of structure and significant difference in size of grain on bar cross-section were revealed. In relation to different structures and grain size, the resulting mechanical values of material are different in individual parts of the rolled product as well. Such differences are mostly unacceptable for the customers. The process of rolling of round bars is characterized by oval-circle pass schedule. The final set comprises two-high rolling mills in ASC system (Automatic Sizing Control). Uneven course of deformation across section of the rolled item during the rolling, which is a characteristic phenomenon in all working process, results in different course of strengthening and softening processes. Their kinetics depends on current deformation parameters, particularly temperature, equivalent strain and strain rate.
3D FEM rolling process simulation was performed for the selected final diameter, which is a true reflection of real operating conditions in ASC semi-finishing and finishing mill. Simulation was processed in FORGE application for medium-carbon steel C20. FEM simulation was used as an efficient tool for description of thermal-stress-deformation field across the rolling gap. The main attention was devoted to resulting course of strain rate, strain and temperature. Courses of values of these capacities were processed depending on position of the point of interest in the rolled item cross-section. The courses proved occurrence of non-homogeneity of deformation parameters across the section, which is given by the applied production technology.

- by Richard Fabik and +1
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- Finite Element Analysis (Engineering), Rolling

In this paper, a method based on the finite element vibration analysis is presented for defect detection in rolling element bearings with single or multiple defects on different components of the bearing structure using the time and frequency domain parameters. A dynamic loading model is proposed in order to create the nodal excitation functions used in the finite element vibration analysis as external loading. A computer code written in Visual Basic programming language with a graphical user interface is developed to create the nodal excitations for different cases including the outer ring, inner ring or rolling element defects. Forced vibration analysis of a bearing structure is performed using the commercial finite element package IDEAS under the action of an unbalanced force transferred to the structure via a ball bearing. Time and frequency domain parameters such as rms, crest factor, kurtosis and band energy ratio for the frequency spectrum of the enveloped signals are used to analyse the effect of the defect location and the number of defects on the time and frequency domain parameters. The role of the receiving point for vibration measurements is also investigated. The vibration data for various defect cases including the housing structure effect can be obtained using the finite element vibration analysis in order to develop an optimum monitoring method in condition monitoring studies.

- by Zeki Kiral
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- Mechanical Engineering, Civil Engineering, Signal Processing, Modeling

FPSO (Floating Production Storage and Offloading) menjadi salah satu alternatif pilihan yang diminati Investor. Dari segi investasi lebih efisien dari pada FSO, karena FPSO selain mobile juga dapat melakukan proses produksi, serta reliability dalam pengoperasiannya. Revolusi teknologi di bidang FPSO kini berkembang dari hull form berbentuk kapal konvesional menjadi hull form berbentuk silinder. Ditinjau dari bentuk lambungnya FPSO silinder menawarkan kelebihan-kelebihan antara lain: olah gerak, kompartemen tanki, stabilitas dan kekuatan memanjang yang lebih baik dari FPSO berbentuk kapal. Berdasarkan studi litelatur tersebut, maka dilakukanlah studi perbandinganan performa hull form antara FPSO berbentuk kapal dan FPSO berbentuk Silinder yang akan dioperasikan pada perairan lepas pantai Utara Natuna. Dari hasil analisa kekuatan memanjang FPSO Kapal memiliki moment yang lebih signifikan 417,11 ton.m dan FPSO Silinder 45,53 ton.m. Dilihat dari olah geraknya FPSO Kapal memiliki gerakan heave yang lebih baik dari silinder saat sudut gelombang 90°,135°, dan 180°. Namun FPSO Silinder memiliki gerakan Roll, dan Pitch yang lebih baik dari FPSO Kapal saat sudut gelombang 90°,135°, dan 180°. Berdasarkan hasil analisis numerik yang dilakukan tersebut, keduanya layak untuk beroperasi namun FPSO Silinder lebih banyak menawarkan keunggulan performa. Dari keunggulan yang ditawarkan tersebut, FPSO Silinder dapat dijadikan acuan alternatif pilihan hull form yang lebih menguntungkan untuk dioperasikan di lepas pantai Indonesia khususnya Utara Natuna -Indonesia.

- by Ahmad Zakki
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- Reliability, Rolling

Sequence design for shape-rolling processes consists of roll pass and profile design, i.e., transforming the billet into a final shape. For the prediction of the mean effective strain of the workpiece during rod rolling, an analytical model by Shinokura and Takai was used. They verified the formula by applying it to a variety of rod-rolling geometries (oval-square, oval-round, square diamond, and diamond-diamond). Today, on the other hand, the finite element (FE) techniques allow analysis of rolling processes in such a way as to simplify the work of design engineers. In this study, a round-oval pass and a round-flat oval pass are analyzed for steel rod rolling. In particular, the analysis of the spread, the surface profile, and cross-sectional area of the workpiece were conducted during rolling. Experimental data such as the maximum spread and the radius are compared with the results of the analytical model and FE analysis.

- by F. Lambiase and +1
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- Hot Rolling Processes, Hot Rolling, Rolling, Hot and Cold Rolling

Keywords: Charpy impact testo Toughnesso Ultrafine-grained materialso Intercritical annealingo Medium Mn steelo Brittle-ductile transitiono a b s t r a c t The effects of prior austenite (g) grain boundaries and microstructural morphology on the impact toughness of an annealed Fe-7Mn-0.1C-0.5Si medium Mn steel were investigated for two different microstructure states, namely, hot-rolled and annealed (HRA) specimens and cold-rolled and annealed (CRA) specimens. Both types of specimens had a dual-phase microstructure consisting of retained austenite (g R) and ferrite (a) after intercritical annealing at 640 C for 30 min. The phase fractions and the chemical composition of g R were almost identical in both types of specimens. However, their micro-structural morphology was different. The HRA specimens had lath-shaped morphology and the CRA specimens had globular-shaped morphology. We find that both types of specimens showed transition in fracture mode from ductile and partly quasi-cleavage fracture to intergranular fracture with decreasing impact test temperature from room temperature to À196 C. The HRA specimen had higher ductile to brittle transition temperature and lower low-temperature impact toughness compared to the CRA specimen. This was due to intergranular cracking in the HRA specimens along prior g grain boundaries decorated by C, Mn and P. In the CRA specimen intergranular cracking occurred along the boundaries of the very fine a and a 0 martensite grains. The results reveal that cold working prior to intercritical annealing promotes the elimination of the solute-decorated boundaries of coarse prior g grains through the recrystallization of aʹ martensite prior to reverse transformation, hence improving the low-temperature impact toughness of medium Mn steel.

This paper presents the measurement and analysis of rolling tire vibrations due to road impact excitations, such as from cobbled roads, junctions between concrete road surface plates, railroad crossings. Vibrations of the tire surface due to road impact excitations cause noise radiation in the frequency band typically below 500 Hz. Tire vibration measurements with a laser Doppler vibrometer are performed on a test set-up based on a tire-on-tire principle which allows highly repetitive and controllable impact excitation tests under various realistic operating conditions. The influence on the measured velocity of random noise, cross sensitivity and alignment errors is discussed. An operational modal analysis technique is applied on sequential vibration measurements to characterise the dynamic behaviour of the rolling tire. Comparison between the operational modal parameters of the rolling tire and the modal parameters of the non-rolling tire allows an assessment of the changes in dynamic behaviour due to rolling.

- by Wim Desmet
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- Vibrations, Modal Analysis, Vibration, Optical physics

Rolled-up semiconductor tubes of various diameters made of alternating In0.215Ga0.785As/GaAs
layers have been investigated by means of Raman scattering. The optical and acoustic phonon
modes of individual tubes have been studied and compared with the characteristics of the
surrounding material. After tube formation, the frequency of the phonon modes shifts with respect
to the as-grown material and disorder activated modes are observed. The frequency shifts are
related to the residual strain in the tubes through the deformation potential approximation. Good
agreement with atomistic valence force field simulations and x-ray micro-diffraction measurements
is found. By comparison with x-ray data, a Raman strain constant K¼0.65 is proposed for
In0.215Ga0.785As. In the low frequency range, acoustic mode doublets are observed on the tubes
that are absent in the surrounding material. They show clear evidence of the formation of
periodic superlattices after the rolling-up process, and give insight into the quality of their
interfaces

- by Veselin Todorov Donchev
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- Raman, Rolling, Phonon Modes

The purpose of this paper is to give a comparison of the behaviour of heat-resistant austenitic stainless steel X15CrNiSi20-12 and the ordinary S355J0 steel grade during rolling of a special-purpose section for door hinges from 80 × 80 mm stock in caliber rolls under normal service conditions of VÚHŽ special section rolling plant. The X15CrNiSi20-12 steel grade possesses low thermal conductivity and high thermal expansion capacity. The latter leads, together with higher flow stress, to more pronounced spreading of this material. This paper deals with the entire rolling procedure of 61949-type section. The initial position of the rolled stock in caliber rolls plays an important role. Key parameters monitored in the process of plant rolling include the shape of the product, spreading, surface temperatures, surface quality, metallographic structure and torques. Comparisons are made in the first and second roll calibers which are open and do not constrain the spreading. The cross-section shape from the pass no. 5 was then compared with the cross-section obtained by mathematical modelling. The FEM-based software Forge3D enables full-scale rolling procedures to be simulated with flat and caliber rolls, in addition to simulations of forging, extrusion, punching and other processes. Finally, the usability of the simulation tool Forge 3D for VÚHŽ special section rolling plant was explored.

- by Richard Fabik
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- Finite Element Analysis (Engineering), Stainless Steel, Rolling

The grain-structure evolution of three-layered A4343(clad)/A3003(core)/A4343(clad) aluminum brazing sheets was studied by means of electron backscatter diffraction. Three different samples were prepared by cold rolling with 17%, 22%, and 44% reduction, and the brazing treatment was carried out in form of differential scanning calorimetry. Orientation maps of the clad and the core suggested that the grains in the melted and re-solidified clad did not grow epitaxially from the core in case of the 17% and 22% cold-rolled samples. In contrast, the grains in the 44% cold-rolled sample seemed to have been formed by epitaxial growth from the core. Kernel average misorientation (KAM) analysis revealed that the samples cold rolled with 17% and 22% reduction retained a deformed microstructure in the core even after the brazing treatment, but the core of the 44% cold-rolled sample was composed of coarse elongated grains, free from any substructure. The dissolution depth corresponding to the thickness of the core affected by the brazing treatment was proportional to the average KAM of the core.

- by Kwangjun Euh
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- Materials Engineering, Microstructure, Brazing, Epitaxy

Rolling of wrought aluminium matrix composites with hard phase-reinforcements such as SiC, is interesting to produce sheets for engineering constructions due to their light weight combined with good strength and wear resistance. In this work, the hot rolling behaviour is studied for stir-cast composites with matrix of Al 6061 and Al 6082 alloys and fine SiCp particulates with size of 15 m and 8 m and volume fraction up to 30%. For composite casting, optimum casting procedures and materials pre-treatment has been applied for successful insertion of particles into the melt, better particles/matrix wetting and particles distribution, minimized SiC/Al reaction. From thermomechanical simulation, step rolling is defined to be suitable at a strain rate of 1 s −1 rate for each step, using intermediate heat treatment at 450 • C for a period of 10 s to 1 h. Generally, the quality of rolled product was improved with improving casting quality. Successive hot rolling resulted in decreasing void and the agglomeration clusters and hence enhanced mechanical properties are achieved. The flow behaviour under rolling of Al-particulate metal matrix composites, PMMCs, is analysed and the product is characterised for its mechanical properties.

Se abordó el comportamiento microestructural del acero AISI 1045 endurecido mediante la Deformación Plástica Superficial por rodillo, Se establece el mecanismo de endurecimiento del acero por el deslizamiento de los granos en la red cristalina y se demuestra el fenómeno de la acritud, la cual es producto del tensionamiento de los granos cuando el material es sometido al tensionamiento de su estructura cristalina. Se establece el procedimiento experimental realizado después que las probetas fueron sometidas al proceso de deformación.

- by Isnel Rodriguez Gonzalez
- •
- Materials Science, Microstructure, Plastic deformation, Asperity

The equipments in the area of cold rolling of Usimina’s plant in Cubatão are not
coupled to each other, requiring the formation of coils. The process of winding and
unwinding propitiates the occurrence of surface defects in the processed strip,
obliging the scrapping of material. One of the more significant problems related to
coiling steel strip are the so-called skid marks. These marks are caused by slippage
(with friction) between one layer of the coil and the other thereafter. The present work
aims to minimize the defect "skid marks" acting on the winding and unwinding
tensions of the tandem cold mill and skinpass mill no.2.

- by Karl Kristian Bagger
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- Quality, Cold Rolling and Galvanising of Steel, Cold Rolling, Mandrel

A precise final geometry of flat-rolled wires is required in view of their industrial applications. However, comparison between experimental and computed cross-sections shows a gap of 10%. This difference might originate in the anisotropy introduced by wire drawing. Coefficients of an anisotropic constitutive model (Hill 48) have been identified from transverse compression tests. Then Lam3®, a finite element software, has been used to simulate rolling passes. The anisotropic law previously established significantly improves the estimation of the final width: yet the underestimation of the experimental width is 5% instead of 10%. Possible ways for further improvement are discussed.

- by Lionel Fourment and +1
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- Finite Element, Anisotropy, Industrial Application, Cross Section

The aim of this paper is to critically assess the potential of mathematical modelling which uses finite element method software for solving operation problems in the hot rolling of flat and long products. We focused on concrete issues faced by rolling plants in the Moravian-Silesian region (Czech Republic). The investigation was always combined with field or pilot measurements or laboratory experiments.

- by Richard Fabik and +1
- •
- Finite Element Analysis (Engineering), Rolling

The I1 intrinsic stacking fault energy (I1 SFE) serves as an alloy design parameter for ductilizing Mg alloys. In view of this effect we
have conducted quantum–mechanical calculations for Mg15X solid-solution crystals (X = Dy, Er, Gd, Ho, Lu, Sc, Tb, Tm, Nd, Pr, Be, Ti, Zr, Zn, Tc, Re, Co, Ru, Os, Tl). We find that Y, Sc and all studied lanthanides reduce the I1 SFE and render hexagonal closed-packed (hcp) and double hcp phases thermodynamically, structurally and elastically similar. Synthesis, experimental testing and characterization of some of the predicted key alloys (Mg–3Ho, Mg–3Er, Mg–3Tb, Mg–3Dy) indeed confirm reduced I1 SFEs and significantly improved room-temperature ductility by up to 4–5 times relative to pure Mg, a finding that is attributed to the higher activity of non-basal dislocation slip.

- by Dierk Raabe
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- Quantum Mechanics, Ab initio calculations, Rare Earth Elements, Magnesium

Materials Science and Technology is published monthly and covers the science, fabrication, and engineering use of metals, ceramics, cements and concrete, polymers, composites, adhesives, and electronic materials.

Usiminas as a company that has the expertise in manufacturing flat steel products in aim to hold and increase the leadership in the production and market of these products has invested huge amount of money in modernization of the hot rolled products manufacturing. The Hot Mill installed in 2012 at Cubatão Plant is one of the most modern in the world. Aggregating added value on the products profitilium the New Continuos Pickling completes the line of products offering increasing the range in dimensions and qualities. The Mix of hot rolled products now attends to thinner gauges as wider widths, beyond steel grades not offered before. This work aims to demonstrate the main steps of this project and the benefits and results achieved with the installation of new production line, this being the state of the art production of pickled, endowed with a high technological level that ensures obtaining products with high added value, meeting the most stringent quality standards.

- by Karl Kristian Bagger
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- Quality, Coils, Steel, Cold Rolling and Galvanising of Steel

The paper deals with the dynamic phenomena accompanying the wheel rolling over a road (rail, track), with lateral slip effects. They occur in rolling of a wheel and wheelset on a straight track in the case of lateral load and especially on curves. Different curvature radii and rotary oscillations of wheelsets result in skew rolling and, in turn, in lateral slip oscillation in the contact zone between the wheel and rail. It significantly increases noise and wear in real structures. Double periodicity of motion was detected in an underground train. Hitherto, this phenomenon has not been reported in the literature. Experimental investigation was performed on a test stand for various parameters: the angle of skew rolling, velocity and contact pressure. Results were related to a two degree-of-freedom theoretical system. In the case of steel/polyester and polyamide/polyester friction pair, qualitatively similar results were obtained.

The variable gauge rolling process is a new technology designed to produce flat products of different thicknesses such as longitudinal profile (LP) plates and tailor rolled blanks (TRB), which are used in bridge building, shipbuilding, and automobile manufacturing, etc., to decrease the weight and the welding times, etc. In this paper, a series of numerical studies on the wave motion of rolling force in variable gauge rolling (in three stages: down rolling, flat rolling, and upper rolling) were carried out using the finite element method to obtain the deformation of the work piece at different stages of rolling. The rolling force and its wave motion during rolling were analyzed under a variety of reduction ratios, including the coefficient of friction, initial thickness of the plates, and diameters of the rolls. The rolling force obviously increases as the reduction in the down rolling process increases, and then decreases during upper rolling. The rolling force consists of two abrupt wave motions in the transitional zones during the down to flat rolling stage, and the flat to upper rolling stage. These results are significant with regards to precisely controlling the deformation of workpiece in the transition zone during variable gauge rolling.

- by Hailiang YU
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- Materials Engineering, Process Control, Finite element method, Steel

Slab edging with plain rolls is one of the techniques for reducing the width of the hot-rolled strip in a roughing mill. This rolling method reduces the strip width and forms a product with a dog bone shaped section. The following rolling in a horizontal mill eliminates the dog bone shape and reduces the strip thickness. The combination of the above processes is often described as vertical-horizontal (V-H) rolling. This paper presents a comparison between results of laboratory slab edging in vertical stand and the results of mathematical modelling using the finite-element method. The paper provides a detailed description of digitization of the slab cross-section shape upon laboratory rolling and solutions to problems with determining its geometrical centre and aligning with the system of coordinates. The mathematical analysis was performed with the aid of the software Forge 2009. Inverse analysis principles were employed for finding the basic initial and boundary conditions and simulation parameters (mesh density, maximum and minimum time increment) in order to achieve an optimum agreement between the resulting shape and the outcome of the laboratory rolling and between calculated and measured rolling forces. The most important factors affecting the metal flow in the roll gap include the friction, flow stress and temperature field homogeneity. The present experiment confirmed the previous experience that with mathematical modelling it is very difficult to arrive at dimensions approaching the results of in-service or laboratory simulations.

- by Richard Fabik
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- Finite Element Analysis (Engineering), Rolling

The theory of kinetics of static recrystallization of steel during hot forming links the phenomenon to certain critical strain, grain size, strain rate, activation energy and temperature. The basic description is provided by the Avrami... more

- by Jiří Kliber
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- Kinetics, Recrystallization, Rolling

- by Rani Rafika Sari
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- Reliability, Rolling

Although Mg-Li alloys have been recognized as super-light structural alloys which have considerable ductility, weak strength and low corrosion resistance have limited their applications. To achieve proper strength and formability simultaneously, for the first time, dual-phase magnesium-lithium alloy is used to fabricate AA1050/MgLZ91 composite. Also, in this paper, for the first time, Mg-Li alloy has been utilized to fabricate three layered laminated sheets in various strain rate. The ARB process is utilized to produce laminated composite specimens at ambient temperature in four separate cycles and microstructure and mechanical properties evaluation are accomplished for all samples. Results showed that despite the process performed at ambient temperature, the adhesion quality of the layers was very high, and the magnesium-lithium layers were completely continuous in the aluminum matrix. The main reason was the high ductility of this alloy and its flow properties close to aluminum at ambient temperature. By applying high strain, the mechanical properties, including strength and microhardness of both layers, were greatly enhanced. In the fourth pass, the UTS value reached 225.8MPa that soared by 276% and 84%, compared to the Al and LZ91, respectively. Compared with other Al/Mg composites, more than three times, the ductility was obtained. Much of the modification were the result of the work hardening and fine-graining mechanism, of course, the extraordinary ductility of the magnesium-lithium alloy at ambient temperature.

- by Davood Rahmatabadi and +1
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- Microstructure, Metal Forming, SEM, Mechanical properties

The surface quality is essential for cold-rolled. During the lamination of skin pass variations may occur in the control of elongation. Control of elongation is achieved by the difference in speeds (VE and VS), obtained by two pulse generators, attached to two rollers deflectors with or without mechanical drive. Over time these coils deflectors suffer damage on its surface, reducing the useful life and causing sliding of the material and consequently the change in control of elongation. We analyzed the conditions of wear of the roll, doing a study for the change of the coating with the increase of friction between the strip and the surface of the deflector roll. The result obtained with the change of the coating was the reduction of the standard deviation of the elongation in the skin pass mill, resulting in significant gains in income end of the cold rolled product.

- by Karl Kristian Bagger
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- Steel Making, Mechanical properties, Coils, Steel

The aim of the paper is to emphasize the role of anisotropy on metal flow in a bulk forming process, namely on lateral spread in pearlitic steel flat wire cold rolling. A precise final geometry of flat-rolled drawn wires is required in view of their industrial applications. Numerical modelling is undertaken to optimize the process and product properties. However, in the first part of the present study, the comparison between experimental and computed cross-sections shows a 10% discrepancy. It is shown first that temperature and friction are not the reasons for this underestimation, then that anisotropy may explain it. Indeed, ovalization of radially cut compression samples is observed at the end of wire-drawing, highlighting the appearance of wire-drawing-induced plastic anisotropy. Coefficients of Hill's quadratic anisotropic constitutive model have been identified at several stages of the wire-drawing and rolling process, using compression and shear tests, in order to study the sensitivity of the process to anisotropy and its influence on lateral spread. Then, the Finite Element Method (FEM) has been used to simulate rolling passes. Taking into account plastic anisotropy significantly improves the estimation of the final width; yet the underestimation is still 5% (instead of 10%). On the one hand, these results unambiguously prove that plastic anisotropy has an impact on flow during cold metal forming processes, provided free surfaces are present. On the other hand, they show further improvement is needed; it is suggested to use more sophisticated anisotropy models, as it has been done in sheet metal forming.

- by N. Persem and +2
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- Materials Engineering, Mechanical Engineering, Metal Forming, Sheet Metal Forming

In this paper, the effects of the flow stress of the scale and steel, and the friction coefficients at the scale–steel and the roll–scale interfaces on the final surface roughness have been studied. The surface roughness increases for both oxide scale and steel with an increasing friction coefficient at the roll–scale interface. However, the roughness increment is limited. The calculated

- by Dongbin Wei
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- Mechanical Engineering, Lubrication, Tribology, Surface Roughness