Rolling

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.

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.

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.

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.

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:

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

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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