Rolled Sheets Research Articles

Investigation of the Effect of Steel Plate Size and Elevated Temperature on Critical Load in Stability Tests

This paper presents the results of a study of the effect of epoxy-polyester-based powder coatings on the critical strength of plate samples made of rolled sheet steel. The results obtained show that the model using flat elements gives a more accurate result than the model using three-dimensional elements. The best agreement with the experiment was shown by the results obtained in Ansys using the Eigenvalue bucling function, less than 1%. The worst agreement with the experiment was shown by the results obtained in Ansys using Solid elements, about 70%.

Shear banding behavior of AA2099 Al-Li alloy in asymmetrical rolling and its effect on recrystallization in subsequent annealing

AA2099 Al-Cu-Li alloys were rolled by both asymmetrical and conventional rolling to a total thickness reduction of 80% at room temperature. Microstructure and texture evolution through thickness of rolling sheets were comprehensively investigated. Results show that large shear stress in ASR sample gave rise to a distortion of grain structure and a remarkable work hardening at region close to fast rolled surface. Shear banding behavior was largely promoted by ASR and various types of shear bands with higher density were observed. The shear bands triggered a kink of grain structure during rolling process. The kink behavior was related to the tilt angle and width of shear bands. The shear bands exhibited large tilt angle and width gave rise to a more significant kink of the grain structure nearby. Recrystallization during subsequent annealing was also promoted by ASR. Shear bands became favorable nucleation sites for rolled material. Growth advantage of some nuclei inside shear bands had a stronger influence on the recrystallized texture in AA2099 rolled sheets.

An Efficient Multi-Scale Modeling Method that Reveals Coupled Effects Between Surface Roughness and Roll-Stack Deformation in Cold Sheet Rolling

Abstract In thin-gauge cold rolling of metal sheet, the surface roughness of work rolls (WRs) is known to affect the rolled sheet surface morphology, the required rolling load, and the roll wear. While modeling of rough surfaces using statistical asperity theory has been widely applied to problems involving semi-infinite solids, the application of asperity distributions and their elastic-plastic behavior has not been considered in roll-stack models for cold sheet rolling. In this work, a simplified-mixed finite element method (SM-FEM) is combined with statistical elastic-plastic asperity theory to study contact interference and coupling effects between a rough work roll (WR) surface and the roll-stack mechanics in cold sheet rolling. By mixing equivalent rough surface contact foundations, Hertz foundations, and Timoshenko beam stiffness, an approach is created to efficiently model interactions between the micro-scale asperities and the macro-scale roll-stack deformation. Nonlinearities from elastic-plastic material behavior of the asperities and the sheet, as well as changing contact conditions along the roll length, are also accommodated. Performance of the multi-scale SM-FEM approach is made by comparison with a continuum finite element virtual material model. 3D studies for a 4-high mill reveal new multi-scale coupling behaviors, including nonuniform roughness transfer, and perturbations to the sheet thickness “crown” and contact force profiles. The described multi-scale SM-FEM approach is general and applies to rough surface contact problems involving plates and shear-deformable beams having multiple contact interfaces and arbitrary surface profiles.

Infrared Nanospectroscopy Reveals DNA Structural Modifications upon Immobilization onto Clay Nanotubes.

The growing demand for innovative means in biomedical, therapeutic and diagnostic sciences has led to the development of nanomedicine. In this context, naturally occurring tubular nanostructures composed of rolled sheets of alumino-silicates, known as halloysite nanotubes, have found wide application. Halloysite nanotubes indeed have surface properties that favor the selective loading of biomolecules. Here, we present the first, to our knowledge, structural study of DNA-decorated halloysite nanotubes, carried out with nanometric spatially-resolved infrared spectroscopy. Single nanotube absorption measurements indicate a partial covering of halloysite by DNA molecules, which show significant structural modifications taking place upon loading. The present study highlights the constraints for the use of nanostructured clays as DNA carriers and demonstrates the power of super-resolved infrared spectroscopy as an effective and versatile tool for the evaluation of immobilization processes in the context of drug delivery and gene transfer.

Simulation of Process Rolling Plates from Alloy of Al-Mg System Economically Doped with Scandium

The modes of hot and cold rolling of plates from an alloy of the Al-Mg system alloy, doped with scandium in the range of 0.10-0.12%, are modeled. At the first stage of work, using the DEFORM-3D software package, we simulated the process of hot sheet rolling at the Quarto 2800 mill, in order to obtain a billet for further cold rolling. Analysis of the simulation data showed that with the adopted compression mode, the metal forming and temperature conditions of rolling make it possible to obtain plates up to 45 mm thick, without defects, with rational power loading of the equipment. Further modeling of the regime of cold rolling of plates with a thickness of up to 31.5 mm showed that cold rolling can be carried out in 4 passes, provided that the stress and rolling force do not exceed the permissible values. At the second stage of work, we conducted an experimental verification of the obtained simulation results both in industrial and in laboratory conditions. It was found that the value of the total compression leading to the destruction of the samples, depending on the rolling conditions, should not exceed 21-30%. At this degree of deformation, the rolled metal from the alloy under study has high strength and plastic properties. Subsequent industrial verification of the research results confirmed that this alloy is quite advanced technologically, while it has high deformability, both during hot and cold rolling, which allows us to recommend it for sheet deformed semi-finished products in the manufacture of structural products for various purposes.

Elemental Characteristics and Source-Apportionment of PM2.5 During the Post-monsoon Season in Delhi, India

In this study, we have coupled measurements, modeling, and remote sensing techniques to better delineate the source characteristics and variability of air pollutants in Delhi primarily during the post-monsoon season in 2019. We show a comparison of ambient PM2.5 (particulate matter having aerodynamic diameter ≤2.5 μm) levels and associated elements during the post-monsoon with those during a relatively clean season of monsoon (experiencing frequent wet precipitation). Air-mass back trajectories from Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model have been used to infer the possible source pathways of PM2.5 impacting at the receptor site in Delhi. The average concentrations of PM2.5 during monsoon (June–July) and post-monsoon (October–November) were 42.2 ± 15.5 μg m−3 (range: 22–73 μg m−3) and 121.4 ± 53.6 μg m−3 (range: 46–298 μg m−3), respectively. The PM2.5 samples were analyzed for heavy and trace elements (Si, S, Na, Mg, Al, Cl, Ca, K, Ti, V, Cr, Mn, Fe, Ni, Cu, Br, Rb, Zr, and Pb) using an Energy Dispersive X-ray Fluorescence (ED-XRF) technique and their concentrations have been used to carry out the source-apportionment utilizing principal component analysis (PCA) tool. The PCA analysis has identified three major sources of fine aerosols including contributions from the sources viz. vehicular emission, biomass burning, coal combustion, secondary aerosols formation, soil dust, solid-waste burning and industrial emission. The source involving biomass burning contributed largely to the PM2.5 in post-monsoon season through long-range transport of large-scale agriculture-residue burning emissions (occurring in the states of Punjab, Haryana, and western part of Uttar Pradesh). The industrial emissions include primarily, medium- and small-scale metal processing industries (e.g. steel sheet rolling) in Delhi-National Capital Region. Traces of emission from coal based thermal power plants and waste incineration have also been observed in this study.

Effect of Thin Polymer Layers on Mechanical Properties of Metal Surfaces

: A study of the effect of epoxy-polyester powder coatings on the mechanical properties of plates made of rolled sheet steel has been carried out. The effect of a coating with a thickness of about 100 μm on the mechanical properties of samples with a thickness of 0.7-1.5 mm was considered. Tests carried out at room and elevated temperatures showed that thin coatings insignificantly affect the mechanical properties of plates in bending and tensile tests. In particular, the stiffness of the plates under tension and bending practically does not change in the presence of coatings, despite the fact that the modulus of elasticity determined in tests of steel plates with coatings is always slightly lower than the Young's modulus of steel, due to the increased thickness of the samples, determined taking into account the presence of coatings. In contrast, in compressive strength tests, the effect of coatings is significant. In the supercritical deformation mode, the bearing capacity of the coated plates is significantly reduced, and their critical buckling load is 1.2–2.3 times lower (depending on the substrate thickness) in comparison with uncoated specimens. This effect can be explained by the influence of residual temperature stresses arising in the samples after the deposition of coatings.

Texture development and dislocation activities in Mg-Nd and Mg-Ca alloy sheets

Texture modification during sheet rolling appears differently in binary Mg-RE (rare-earth) or Mg-Ca alloy, compared to their ternary counterparts containing Zn. The differences in texture development and the active deformation mechanisms under tensile loading were investigated in the binary alloys. These analyses are based on in-situ synchrotron experiments and electron backscatter diffraction measurements to reveal direct experimental evidence of the texture development and the active deformation mechanisms. Higher activations of nonbasal <a> and pyramidal <c+a> dislocations were found in the Nd or Ca containing Mg alloys, compared to the Mg-Zn alloy. The texture development shows an obvious feature, which is a broadening of the basal pole intensity distribution perpendicular to the loading direction and a strengthening of the <101¯0> pole at the loading direction in all examined sheets. This texture development relates to the higher activation of prismatic <a> slip. The addition of Zn in the Mg-RE or Mg-Ca alloys further promotes the activation of nonbasal <a> and pyramidal <c+a> dislocations. This enhanced prismatic <a> slip in the Zn containing ternary alloys is confirmed by EBSD misorientation analysis.

Mechanical Properties and Structural State of Rolled Sheets from High-Strength Wear-Resistant Weldable Steel H500 Magstrong®

A process of manufacturing of rolled sheets from a new high-strength wear-resistant weldable steel H500 MAGSTRONG® with wear resistance, strength and impact toughness parameters at negative temperatures not inferior to those of the best world counterparts is described. Transmission electron microscopy is used to study the structure of a sheet with a thickness of 12 mm formed as a result of hot rolling and quenching.

Effect of Annealing Temperature on Microstructure, Texture and Earing of 8011 Cold Rolled Sheet

To reduce the work hardening of the 8011 cast-rolled plates after multiple rolling, 8011 cold-rolled plates with a deformation of 78% were annealed at different temperatures. The influence of annealing temperatures exercise upon the microstructure, texture and earing of cold-rolled sheets was analysed by means of ODF texture analysis, EBSD technology and cup drawing test. The results show that the contents of the deformed microstructure, the recrystallized structure and the substructure change sharply annealing at 300°C, but they tend to be stable at 350°C. The starting temperature of recrystallization of 8011 cold-rolled plates is about 300°C. When cold rolled sheets were annealed at low temperatures, there were quantities of grain boundaries whose angle was small. When the annealing temperatures were higher, the small and medium angle grain boundaries of the cold rolled sheets decreased gradually. The general trend was that the small angle grain boundaries first increased and then decreased as the case of annealing temperature rise. The proportion of the small angle grain boundaries reached to the minimum value of 20.2% at 350°C. When annealing temperature is 350 °C, the lowest earing rate is 2.11%.

Development of modes for straightening of hot-rolled strip in order to obtain rolled products for high-tech processing

Modern requirements for the quality indicators of hot rolled sheet steel are associated with maintaining high flatness of sheet metal during further processing by high-tech methods, for example, by laser or plasma cutting. When laser cutting a sheet it may bend due to the release of residual stresses that are unevenly distributed over the volume. The final stage in the production of hot rolled steel is straightening on roller straightening machines under cyclic alternating deformation. The solution to the problem is the optimal control of residual stresses at the main final stage of hot rolled sheet production when straightening strips on roller levelers under cyclic alternating deformation. The existing numerous approaches of calculating the parameters of the straightening on roller straightening machines do not allow determining the optimal modes that eliminate the initial inhomogeneous stress state of the hot rolled strip and ensure the minimum level of residual stresses in the rolled product. The paper substantiates the relevance of developing a methodology for selecting a strip straightening mode, which provides an expansion of the possibilities of the straightening process on roller straightening machines and obtaining hot rolled sheets with a minimum level of residual stresses and potential energy, suitable for plasma and laser cutting. The article describes the implementation of the method for selecting the mode of hot rolled strip straightening process based on the results of finite element modeling, confi rmed by experimental data obtained during leveling and subsequent cutting of sheets. The modes of straightening of strips with a thickness of 4 mm, 8 mm and 10 mm of steel grade S355MC have been calculated on 13-, 15- and 17-roller straightening machines of Severstal, providing minimum residual stresses, potential energy in sheets after straightening and deviations from the flatness of sheets during high-tech cutting. Based on industrial tests, the method for calculating straightening modes was introduced into production, the developed modes were accepted for use at Severstal. The proposed improvements of technology of the production of hot rolled sheet metal in the conditions of Severstal made it possible to obtain products suitable for laser cutting.

Recovery and recrystallization in molybdenum studied by positron annihilation and X-ray methods

The study investigated the recrystallization and induced changes in positron annihilation characteristics and the crystallographic texture of rolled molybdenum sheets as a function of annealing temperature. After deformation, the positron lifetime spectrum revealed dislocations and divacancies, however, above 200 °C where the recovery process of the deformed material began clusters with five vacancies were detected. Above 500 °C the step-like dependence of the mean positron lifetime on temperature was registered which is associated with recrystallization as was proofed by XRD measurements. This type of dependency can be well described using the positron diffusion model, which allows determining the activation energy of the grain boundary migration. This energy was determined as equal to 1.41 ± 0.23 eV. Variation of positron lifetime with temperature can be linked with changes in the texture. The rotated cube {100} 〈110〉 component dominates in the rolled material texture. The {111} <110> − {111} 〈112〉 fiber, typical for the recrystallization texture were registered for the samples annealed at 800 °C and 1050 °C.

Study on tribological behavior, lubrication and anti-corrosion properties of W/O microemulsion for cold rolling of copper strip

PurposeThe purpose of this paper is to improve lubrication and anti-corrosion properties of the water-in-oil (W/O) microemulsion for rolling of copper strip and sheet to replace the traditional rolling oil.Design/methodology/approachThe W/O microemulsion is prepared by using hydrogenated base oil, a deionized aqueous solution of 0.03 mol/L of Na2SO4 and composite emulsifier such as Sp20, Tx-7 or sodium petroleum sulfonate. Tribological behavior of the microemulsions and traditional cold rolling oil was conducted by MR-10A four-ball tester. The lubrication performance of microemulsion for cold rolling of copper strip was performed by cold-rolling experiment. The morphology of worn surface and the rolled copper was characterized. Anti-corrosion properties of microemulsion for rolled copper was investigated, and the corroded surface was analyzed by X-ray photoelectron spectrometer (XPS).FindingsThe results show that the extreme pressure and antiwear properties of the microemulsions have been improved; the average friction coefficient of the improved microemulsion is 0.065, which is 30% lower than the commercial cold rolling oil. For cold rolling of copper strip, the microemulsion has a higher thinning effect than the commercial cold rolling oil, and a smooth surface is obtained and the surface roughness (Sa) is decreased by 6.8%. The XPS analysis indicated microemulsion adsorbed on the copper surface mitigate the corrosion of oils.Originality/valueThis paper used the prepared W/O microemulsion as a new lubricant in the process of rolling for copper strip and sheet in industry, demonstrating the microemulsion has broad application prospects in the future.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-06-2020-0227/

An effective rolling process of magnesium alloys for suppressing edge cracks: Width-limited rolling

To suppress the edge crack of the magnesium alloy sheet during the ordinary rolling process, a new rolling process named width-limited rolling was proposed in this paper. Width-limited rolling is a rolling method in which the width of the alloy sheet is limited by modifying the shape of the rollers, allowing a compressive stress field to form at the edge portion of the alloy sheet during rolling, resulting in the reduction of edge cracks. At present work, magnesium alloy sheets were separately subjected to ordinary rolling and width-limited rolling. The microstructure evolution and mechanical properties of the rolled sheets were investigated by EBSD, TEM, and XRD. The results exhibited that under the same rolling conditions, the sheet after ordinary rolling exhibited obvious edge cracks while no crack was found at the edge of the sheet after width-limited rolling. The edge crack suppressing effect was attributed to the reduction of the tensile stress along rolling direction during WLR, promoting the synchronous extension of the edge and center regions to suppress edge crack tendency. Microstructure observation showed that the compressive twins formed in the sheet after ordinary rolling usually exhibited as thin plates and cannot continue to fully develop due to the premature generation of the edge cracks. However, the compressive twins developed maturely in some of which double twins formed and various slip systems with different dislocation Burgers vectors occurred in the rolled sheet after WLR. More twin intersections and shear bands, providing more potential recrystallization nucleation sites, which are beneficial to weaken basal texture. With the cooperation of twinning and dislocation slip, the texture of the sheet after the width-limited rolling is weakened and the mechanical properties are improved.

Blank thinning predictions of an aluminum alloy in hole expansion process using finite element method

The main objective of this study is to accurately predict the thinning behavior of AA6016-O aluminum alloy in the hole expansion test. In order to perform this aim, three yield functions, namely isotropic von Mises, quadratic Hill48 and non-quadratic Yld91, are considered and their prediction capabilities are evaluated in this study. Firstly, finite element (FE) model of hole expansion test is created by implicit FE software Marc, then FE simulations are performed with each yield criterion. In order to assess prediction capabilities of these yield criteria, thickness strain distributions along the three directions of the sheet (rolling, diagonal and transversal) and punch force–displacement curves are investigated. The results predicted from FE analyses are compared with experimental results. From the comparisons, it is observed that Yld91 yield criterion could successfully predict the thickness strain distributions along the rolling and transverse directions, whereas the other two criteria could only predict the thickness strain distributions along the diagonal direction. On the other hand, it is determined that punch force–displacement curves predicted from three models are identical and these predictions are overestimated compared to experimental data.

Evolution of Strain State of a Rolled Aluminum Sheet in Multi-Pass Conventional Spinning

Abstract This study clarified the strain state evolution of a cylindrical cup spun from a rolled aluminum sheet in 13 passes. Measurements of radial (ɛr), circumferential (ɛθ), and thickness (ɛt) directional strains as well as forming forces revealed that the strain state evolved as follows: the cup-wall exhibits ɛr &amp;lt; 0 and small |ɛθ| and |ɛt| in early passes and ɛr &amp;gt; 0, ɛθ &amp;lt; 0, and ɛt &amp;lt; 0 in later passes; meanwhile, the cup-edge exhibits ɛr &amp;gt; 0 and small |ɛθ| and |ɛt| in early passes and ɛr &amp;gt; 0, ɛθ &amp;lt; 0, and ɛt &amp;gt; 0 in later passes. The relationship between the strain states and the forming force is interpreted as follows. The normal direction forming force, which pushes into the workpiece in the thickness direction, primarily deforms the workpieces. The radial direction forming force, toward the edge along the workpiece configuration, facilitates elongation in the radial direction of the cup-wall and results in ɛr &amp;gt; 0 during spinning. By contrast, a small radial direction forming force or a forming force whose direction is inverse against the roller movement direction restrains to elongate the material in the radial direction and facilitates shrinkage, thereby resulting in ɛr &amp;lt; 0 in the cup-edge in early passes. Furthermore, the small or inverse directional force facilitates the accumulation of the material to the edge and results in ɛt &amp;gt; 0 in latter passes.

Computer modelling-based selection of accelerated cooling parameters for advanced high-strength structural steel

The article describes the working principles and configuration of the computer system applied for selecting parameters of accelerating water cooling of rolled sheets made of low-carbon advanced strength steel. The system is based on mathematical models using empirical regression equations that describe the interconnections between working parameters of cooling equipment and the technological parameters of thermal processing. The equations are outlined and discussed. The results of computer modelling verification in industrial trials are presented. The case-study involved computer system concerning steel properties and microstructure is described.

Design of automatic system of lead sheet roll for fishing gear industry

In this paper, we report an automatic system which combines machine design and machine vision to promote the automatic lead sheet roll production. In terms of the key problem identifying and locating millimetre-level slit in motion, the rotating module and the slit recognition module are designed based on the geometric characteristics of the lead sheet roll hub, and machine vision technology is used to extract the features of slit images. The automatic system enhances the production efficiency of lead sheet roll by nearly 8 times and lowers the production cost.

The significance of hot rolled microstructure controlled by fine-tuning Al content to texture evolution and magnetic properties of low silicon non-oriented electrical steels

In non-oriented electrical steels, the initial hot rolled microstructure usually had important effects on the successive microstructure and texture development during cold rolling and annealing and the final magnetic properties. In this paper, we reported that the hot rolled microstructure of a 0.4 wt% Si steel could be controlled by designing Ar1 (γ/α phase transformation temperature), which was susceptive to the content of Al. Three steel slabs with different Al contents (0.41, 0.30 and 0.21 wt%) were produced and then subjected to the same hot rolling, cold rolling and annealing treatment in an industrial production line. Interestingly, it was found that, the heavily elongated deformed grains were reduced or even avoided in the hot rolled sheets by decreasing Ar1 with a slight decline of Al. As a result, after cold rolling and annealing, weak γ-fiber (〈111〉//ND) texture and bigger grains were obtained. Hence, the magnetic properties were significantly improved, i.e. high magnetic induction (B50) together with low iron loss (P1.5/50). The microstructure and texture evolutions of these three steels throughout the whole processing route were comparatively investigated in detail, and the effects on magnetic properties were discussed in terms of the classical loss separation theory. This work also provides a promising method to optimize the microstructure, texture and magnetic properties for other low silicon non-oriented electrical steels.

Synergistic Enhancement of the Strength-Ductility for Stir Casting SiCp/2024Al Composites by Two-Step Deformation

The 10 μm 10 vol% SiCp/2024Al composites sheet was successfully fabricated by semi-solid stir casting followed with two-step deformation (extrusion and rolling). The two-step thermal deformation solves the sheet rolling formability of the SiCp/2024Al composites produced by stir casting. Compared with the SiCp/2024Al composites prepared by traditional powder metallurgy, this paper innovatively studied the synergistic enhancement between CuAl2 phase and SiCp on the mechanical properties. The result shows that the two-step deformation can significantly improve the uniformity of the distribution of SiCp and CuAl2 phases. At the same time, the average size of the SiCp and CuAl2 phase decreases after the two-step deformation. During the hot extrusion, SiCp has an obvious hindrance to the refinement of the CuAl2 phase. Moreover, the SiCp/2024Al composites sheet exhibits excellent yield strength (295 MPa), ultimate tensile strength (489 MPa), and elongation (10.42%). The performance improvement of SiCp/2024Al after two-step thermal deformation is mainly attributed to the improved interface bonding strength of SiCp-2024 Al matrix, the refined SiCp and the more uniform distribution of SiCp.