Longitudinal Rolling Research Articles

Effect of combined thermomechanical treatment on structure, mechanical properties, electrochemical behavior and functional corrosion fatigue of biodegradable Fe-30Mn-5Si alloy

In present study, the combined thermomechanical treatment (TMT), including the radial-shear rolling (RSR) at 900 °C followed by longitudinal rolling (RSR+LR) at 700 °C, was applied to biodegradable Fe-30Mn-5Si (wt%) alloy. The effect of these TMTs on the microstructure, phase composition, mechanical properties (ultimate tensile strength UTS, apparent yield stress σ0.2, relative elongation to failure δ, Young's modulus E), electrochemical behavior and functional corrosion-fatigue behavior in Hanks’ solution were studied. It was found that RSR leads to the formation of a statically recrystallized γ-austenite structure with an average grain size of 10±3 and 20±3 µm in the peripheral and central zones, respectively. The RSR+LR results in a mixture of dynamically recrystallized and dynamically polygonized structures with the average grain size of 5±1 µm. Moreover, RSR and RSR+LR lead to the formation of a single-phase FCC γ-austenite state compared to reference heat treatment (RHT), where microstructure is characterized by a two-phase state of FCC γ-austenite and HCP ε-martensite with an average grain size of 200–300 µm. Based on static mechanical tensile tests to failure, it was established that RSR and RSR+LR lead to a significant increase of UTS up to 770±21 and 935±55 MPa, σ0.2 up to 300±38 and 490±43 MPa, and δ up to 28±2 and 19±10 %, while maintaining acceptable of E value about 165±29 and 150±8 GPa, respectively as compared to 460±41 MPa, 210±91 MPa, 11±3 %, and 140±14 GPa after RHT. The electrochemical studies showed that single-phase structure (FCC γ-austenite) formed after RSR and RSR+LR leads to the non-critical biodegradation rate lowering as compared to the two-phase state (γ-austenite and ε-martensite) after RHT. Besides RSR and RSR+LR lead to significant improvement of functional corrosion-fatigue life in Hanks’ solution.

Time and power dependence of laser-induced photodamage on human sperm revealed by longitudinal rolling measurement using optical tweezers.

Lasers are widely applied in assisted reproductive technologies, including sperm fixation, sperm selection and intracytoplasmic sperm injections, to reduce procedure time and improve consistency and reproducibility. However, quantitative studies on laser-induced photodamage of sperm are lacking. In this study, we demonstrated that, by using optical tweezers, the kinematic parameters of freely swimming sperm are correlated with the frequency as well as the percentage of pausing duration of longitudinal rolling of the same sperm head in the optical trap. Furthermore, by trapping individual sperm cells using 1064-nm optical tweezers, we quantitatively characterized the time-dependence of longitudinal rolling frequency and percentage of pausing duration of sperm under different laser powers. Our study revealed that, as trapping time and the laser power time increase, the longitudinal rolling frequency of the optically trapped sperm decreases with an increasing percentage of pausing duration, which characterizes the effect of laser power and duration on the photodamage of individual sperm cells. Our study provides experimental basis for the optimization of laser application in assisted reproductive technology, which may reduce the photodamage-induced biosafety risk in the future.

Ways to improve the processes of longitudinal rolling on a pipe rolling plant with a plug mill to reduce metal consumption and increase production output

Ways to improve the processes of longitudinal rolling on a pipe rolling plant with a plug mill to reduce metal consumption and increase production output

ОСОБЛИВОСТІ МІКРОСТРУКТУРИ ОСЬОВИХ ЗАГОТОВОК ПІСЛЯ ПРОКАТУВАННЯ

A study of the features of the structure of axle blanks made of steel grade F (AAR M-101-2017 Axles, carbon steel, heat-treated) after longitudinal rolling on a TPA 5-12" pipe rolling unit with pilgrim mills in three crimping modes (1 mode: Ø 470 → Ø 380 → Ø 260 mm; 2nd mode: Ø 470 → Ø 420 → Ø 260 mm; 3rd mode: Ø 470 →Ø 260 mm). Determination of the features of the distribution of deformation work and the formation of the final structure after deformation according to the experimental modes of BLZ Ø470 mm per circle Ø260 mm is the goal of research. It was determined that the uniformity of the grain structure is the highest after the application of mode #3 (Ø 470 →Ø 260 mm).

Структура и механические свойства стали 03Х17Н10М2, легированной серебром

The influence of silver additives in amounts of 0.2 and 0.5% (wt.) on the structure and mechanical properties of thin sheet (1 mm thickness) steel 03Х17Н10М2 (03Ch17N10М2), produced by argon-arc remelting followed by homogenization annealing and hot longitudinal rolling, has been studied. It was established that increasing the silver content from 0 to 0.5% led to a slight decrease in strength (σ0.2 from 560 to 510 MPa, σs from 760 to 710 MP) and microhardness (from 274 to 250 HV), but not below the requirements ASTM A240. The fracture surface of steel in both cases is represented by a set of different-sized self-similar pores (cups) of ductile fracture. The developed steel with a silver content of up to 0.5% (wt.) can be effectively used for products that require antibacterial properties.

TEXTURAL AND STRUCTURAL REGULARITIES OF DEFORMATION BY ROLLING OF Zr-2.5%Nb ALLOY

A review of studies of regularities of changes in the crystallographic texture of the longitudinal and cross rolling of the Zr-2.5%Nb alloy is given. Accordingly with this, plates were made from longitudinal fragments and rings of a tube 15.01.5 mm from the fuel assemblies of Russian RBMK reactors. The plates were annealed at 580 °C for 3 h. X-ray studies of texture changes with the degree of deformation of the plates by rolling were carried out. The principle of method of inverse pole figures was used with the calculation of the Kearns texture coefficients, as well as measurements of tilt curves (0002) was. Non-uniformiity of deformation during straightening of the tube blanks was taken into account. It is found that the main rotations of crystallographic c-axes in the plates at any rolling direction are carried out in the plane corresponding to the cross-section of the original tube. Existence of an initial stage of increased textural changes during deformation of the plates is found, what is qualitatively and quantitatively related to activity of tensile twins of the {1012}[1011] system. Regularities in texture changes at the subsequent moderate stage of deformation with the participation of compression twins are considered. The purely twinning nature of the textural doublet, which latter is characteristic of the rolling texture of metals of the titanium subgroup, is explained. It is noted and explained a fact that during cross rolling of plates (made from tube rings), textural changes occur at a rate twice as high as during longitudinal rolling. As considered, all similar regularities can be carried out for the metals of the titanium subgroup.

The influence of thermomechanical treatment pathways on texture and mechanical properties in ARB Cu/Nb nanolaminates

Accumulative roll-bonded Cu/Nb nanolaminates (ARB Cu/Nb) possess high strength, thermal stability, and radiation tolerance arising from a high content of heterophase interfaces at fine layer thicknesses. These properties can be tailored by processing parameters used in the ARB Cu/Nb fabrication process, in which layer thickness, thermal history, and strain pathway determine the interface types and resultant properties found in the material. In this work, we subject ARB Cu/Nb to annealing, and then two different rolling pathways – one where rolling direction is held constant (longitudinal rolling, or LR), and one where rolling direction is rotated by 90° and held constant thereafter (cross rolling, or CR). Rolling is performed on ARB Cu/Nb over a targeted range of layer thicknesses from 193 to 25 nm and resultant bulk textures measured by neutron diffraction are correlated with mechanical properties measured by miniaturized tensile tests. The annealing procedure sharpens texture in both phases. We find that Cu mostly develops the same texture in LR and CR. In contrast, Nb develops a distinct texture along the CR pathway that is distinct from the LR texture. The composite texture of Cu/Nb is thus distinct between LR and CR pathways. This difference in texture development between Cu and Nb as a function of strain after change in rolling direction demonstrates the viability for deliberate pairing of Cu LR and Nb CR textures at a desired layer thickness. For mechanical properties, we find that differences in texture do not result in yield or flow stress differences above a layer thickness of 25 nm. Below a layer thickness of 25 nm, despite similar Taylor factors, yield and flow stress and are significantly different. This indicates texture only influences mechanical behavior at low layer thickness, where interface structure dominates mechanical properties.

Improvement of Fatigue Properties of EN AW 6082 Aluminum Alloy using Different Deep Rolling Directions

Deep rolling (DR) is an effective mechanical surface treatment method to improve the fatigue properties of engineering components. In this method, the surface of the component was rolled using a roller with a predetermined force to obtain reduced roughness, hardness increases and compressive residual stresses in the surface region. These alterations allow for increasing the fatigue lives of the components in industrial applications. In the current study, DR was applied in tangential and longitudinal directions on specimens that were manufactured using EN-AW 6082-T6 aluminum. The resulting roughness, hardness and residual stresses were determined experimentally. Fatigue tests were carried out to determine the improvements in fatigue properties after DR. It was found that DR-induced compressive residual stresses depend on DR direction considerably. Due to this reason, fatigue strength improvements were found to be different for different DR direction applications. Longitudinal rolling resulted in a 23% fatigue strength increase compared to a 7% increase for tangential rolling. For both DR direction applications, fatigue cracks were shown to initiate at the sub-surface region, whereas the as-turned specimens exhibited surface crack initiation.

Analysis of the transformation of the microstructure of axial billets after rolling

The task of improving the quality of metal products of large cross-sections pro-duced from continuous cast billets (CBS) is associated with a number of difficulties. These include the presence of internal defects in the macrostructure of the workpiece (axial looseness, porosity, liquation, crystallization cracks, etc.). Processing from the point of view of deformation of cast workpieces is necessary first of all to eliminate cast defects. An increase in working out contributes not only to the welding of existing mi-crodiscontinuities and, in this connection, to an increase in the density of the metal, but also to the extraction, crushing and reduction of the cross-section of the existing non-metallic inclusions. However, the dimensions of the elements of the primary structure, which are presented on the graphs, are also of the greatest importance. The smallest level of liquation is formed in the surface areas during crystallization. At the same time, as a rule, it is necessary to obtain a homogeneous structure in terms of grain size on the cross-section of large-sized metal products. A study of the features of the structure of axle blanks made of steel grade F (AAR M-101-2017 Axles, carbon steel, heat-treated) after longitudinal rolling on a TPA 5-12" pipe rolling unit with pilgrim mills in three crimping modes (1 mode: Ø 470 → Ø 380 → Ø 260 mm; 2nd mode: Ø 470 → Ø 420 → Ø 260 mm; 3rd mode: Ø 470 →Ø 260 mm). Determination of the features of the distri-bution of deformation work and the formation of the final structure after deformation according to the experimental modes of BLZ Ø470 mm per circle Ø260 mm is the pur-pose of the research. Samples for the structure study were taken both from the original BLZ and the finished draft axle along the entire cross-section. The greatest unevenness of the liquation background, which is observed in the axial blank manufactured using mode No. 1, is also manifested during the study of the microstructure of railway of the axes obtained by the indicated modes. It was determined that the uniformity of the grain structure is the highest after using mode No. 3 (Ø 470 →Ø 260 mm).

Implementation of a finite element modelling strategy for the prediction of aircraft tyre response

This paper presents the finite element modelling (FEM) strategy to identify the structural response of aircraft tyres under quasi-static and taxiing load conditions. The tyre FEM was developed to simulate the aircraft tyre/ground interaction for a range of inflation pressures under vertical, lateral, longitudinal, torsional, yawed and un-yawed rolling. A thorough comparison for validation purposes is made between the test and simulation data extracted from the FEM. The reinforcement plies of the tyres are modelled in a computationally efficient manner whilst also considering the variable fibre volume fractions and ply discontinuities within the tyre. The accurate material characterisation at coupon level combined with the overall modelling approach allowed most simulated responses to match the experimental stiffness within 12% against best fit curves of similar tyre types and within 5% for the majority of test comparisons.

Toward a 2D/3D Finite‐Element–Based Digital Shadow for the Approximation of Metrologically Inaccessible Dynamic Fields of State Variables during Heavy Plate Rolling

While innovations in metal forming technology are closely linked to material science, automation, and mechatronization in recent decades, nowadays, and in the upcoming years, they are supposed to be driven by digital transformation and virtualization. Motivated by this expectation and the fact that the dynamic, process‐relevant thermophysical state variables in plates during rolling are difficult or even impossible to measure, a modularly structured 2D/3D model, integrated into a digital shadow, is built and validated against a metrologically accessible process data. The decisive innovation of the presented modeling strategy is the investigation of the state during longitudinal rolling in the fillet, depending on the width direction. The fillet marks the heavy plate without head and tail crops, developed during longitudinal rolling. Application of the simulation tool reveals significant temperature gradients near the plate surfaces, both horizontally and vertically, but also a region of nearly constant temperature near the core. The development of the fillet cross‐section shape, including the emergence of bulges or contractions at the side surfaces, is predicted within the simulation. The digital shadow is scalable and has a parameterized structure so that rolling schedules of different compositions can be simulated.

Еxperimental determination of ratio of transverse and longitudinal deformations (Poisson's ratio) during longitudinal rolling

In the analysis of experimental data obtained according to the scheme of the plane stressed-deformed condition (during longitudinal rolling) the dependence of the ratio of transverse to longitudinal deformations coefficient, or Poisson’s ratio for plane stressed-deformed condition are defined. Obtained values differ from the tabular data for the elastic deformed state and from the accepted value in the deformation theory of plasticity.

МОДЕЛИРОВАНИЕ ЗАДАЧИ О СВОБОДНОМ РАСТЕКАНИИ ПЛАСТИЧЕСКОГО СЛОЯ, СОСТОЯЩЕГО ИЗ РАЗНЫХ СРЕД, В ПОСТАНОВКЕ МОДЕЛИ «ИДЕАЛЬНОЙ ЖИДКОСТИ»

The approach under study is important for practical application, since is the basis of many basic plastic deformation operations associated with plastic flow in a thin layer of material deformed by rolls (longitudinal rolling, rolling) or dies (volumetric and sheet stamping), which are described by spatial mathematical models with a variety of parameters that determine the rheology of the material. Pressures are created on the contact surfaces of the processing material with the tool, which exceed the shear characteristics of the material by an order of magnitude, so that, in the initial approximation, it is possible to use the model of a hydrodynamic fluid to describe the properties of the material of the plastic layer [1, 2, 3]. As was shown earlier, sliding is observed almost along the entire contact surface, in which the contact surfaces coincide with the sliding surfaces, and the specific friction forces on them are maximum [4] and equal to the shear yield strength of the material [5, 6]. It should be noted another feature of the course of these processes, which determines the requirements for the accuracy of the final forging. It is clear that high contact pressures cause normal elastic displacements of the working surfaces of the tool, commensurate with the thickness of the plastic layer [7, 8]. We consider a plastic layer in the wedge-shaped region, composed of materials with different mechanical characteristics. the layer spreads freely between the rigid rough slabs converging in parallel. The layer under the action in the direction of the thickness of the distributed load from the side of the tool flows freely in the direction of the radii.

IMPROVEMENT OF THE METHOD FOR CALCULATING DEFORMATION PARAMETERS IN THE ROLL PASS DESIGN FOR THE WIRE MILL

Currently, analytical methods, including system analysis and computer simulating, are widely used in the development and construction of rational roll pass design. However, the known methods and solutions are not exhaustive, which solve the problem completely. The methodology for calculating the parameters of rolling deformation during the calibration of rolls for rolling wire rod in system of the gauges "round-oval-round" on graded modern continuous mills has been developed, taking into account the balance of the forces in the deformation zone and the longitudinal stability of the process. It provides coordination of geometric, kinematic and force parameters in the deformation zones of the rolling mill itself and the wire block.
 The calculation is carried out against the direction of rolling, in terms by the corresponding strip, taking into account temperature conditions and rolling in the field of minus tolerances the dimensions of the metal. Longitudinal rolling stability in every stand is determined based on the calculation the average resulting internal forces of plastically deformable metal. Numerically solving the boundary value problem for the Karman equation with known rolling parameters and changing the entering angle, the corresponding angle of the neutral section is found, the value of which is equal to the found kinematic one.
 The results of the test calculations are quite close to the real data of rolling the round bar and a wire rod with a diameter of 8 mm on a mill 400/200 of PJSC "KAMET-STEEL". At the same time, the broadening of the metal is determined analytically in accordance with the physical conditions of the balance forces and constancy of the seconds’ volumes of the metal in the zones of deformation. The shape of the ovals obtained by the provided method is more convex. The system influence of metal friction conditions in the rolls on the longitudinal stability of rolling and the stability of the process was established.

Chirality and frequency measurement of longitudinal rolling of human sperm using optical trap.

Motility is one of the most critical features to evaluate sperm quality. As longitudinal rolling of human sperm has long been ignored until recently, its detailed dynamics and cellular biological mechanisms are still largely unknown. Here we report an optical-tweezers-based method to evaluate the chirality and frequency of sperm rotation. According to the intensity distribution patterns of off-focus micron-size particles, we established a method to judge the orientation of the sperm head along the optical axis in the optical trap. Together with the rotation direction of the projection of the sperm head, the chirality of longitudinal rolling of sperm can be measured without the application of three-dimensional tracking techniques or complex optical design. By video tracking optically trapped sperm cells from different patients, both rolling chirality and rolling frequency were analyzed. In this study, all the vertically trapped human sperm cells adopt a right-hand longitudinal rolling. The orientation and rolling frequency but not the rolling chirality of sperm in the optical trap are affected by the trap height. The rotation analysis method developed in this study may have clinical potential for sperm quality evaluation.

Characterization of static, fatigue and fracture behaviour of the aluminium-lithium alloy Al-Li 2198-T851

The work reports an extensive experimental campaign for the aluminium lithium alloy Al-Li 2198-T851. Static, fatigue and fatigue crack-growth behaviour was investigated through tests on laboratory specimens manufactured along the longitudinal and transversal orientation with respect to the rolling direction. Microstructure was observed through macro-graphic evaluations and a Scanning Electron Microscope (SEM).It was found that the 2198-T851 provided enhanced mechanical properties with respect to 2024-T3 for both transversal and longitudinal rolling direction. Nonetheless, a significantly different behaviour was observed for the transversal direction that provided mechanical performances from 5 to 30 % lower than those measured longitudinally.

Determination of Limiting Dome Height (LDH) values for Inconel 718 alloy sheet using FEA and Hemispherical Punch Method

In this work, initially the chemical composition of Inconel 718 alloy sheet was obtained using X-ray fluorescence technique (XRF). The material properties such as yield strength, ultimate tensile strength, percentage of elongation, normal anisotropy, planar anisotropy, strain hardening exponent, and the strength coefficient were determined in longitudinal, diagonal, and transverse rolling direction using a uniaxial tensile test. The Limiting Dome Height (LDH) values are obtained by simulation and experimentation based on the hemispherical punch method. In simulation work, Barlat-89 yield criterion was used to obtain the Limiting Dome Height (LDH) values and strain distribution along with the specimen in Abaqus 6.1 software. The experimental LDH values of Inconel 718 alloy sheet and simulated results obtained from Abaqus 6.1 software were in close agreement. The approach presented in this work can be applied to obtain the LDH test values of interesting material focused by researchers. With the help of experiments, a limit curve was established which ensures the safe working region of Inconel 718 sheet. Scanning Electron Microscope (SEM) analysis of 100 &120 mm width specimens indicated smooth surface and ductile fracture. The examination of 140 &160 mm width specimens showed rough surface and shear-ductile failure. Energy Dispersive Spectrum (EDS) analysis of a fractured surface confirms the constituents of the sheet present before failure.

Analysis of the causes of undesirable curvature of the workpiece during longitudinal rolling using numerical simulation

Undesirable additional deformation was observed during the experimental cold rolling of steel. A simulation was performed in Deform software to clarify the causes. The influence of the unequal coefficient of friction, geometric inaccuracies of the rolls and the conveyor, and the situation when the rolls did not have the same diameter or rotated at different speeds were investigated. Simulations with different roll speeds corresponded best to reality. The simulation of the undesired curvature of the workpiece at different speeds of rotation of the rolls and 30% reduction was subsequently performed as an elastoplastic problem in order to determine the amount of springback and residual stress. Furthermore, the press straightening of the workpiece was simulated. Inhomogeneous and accidental deformation and residual stresses must be taken into account, especially when researching the effect of cold rolling on the mechanical properties and structure of the material.

IMPROVING THE SHAPE OF THE TWO-ROLL ROUND CALIBER OF MILL FOR LONGITUDINAL ROLLING OF PIPES ON A SHORT MANDREL

To obtain high-quality pipes, it is necessary to minimize the transverse diversity. To do this, experts create new calibrations of the mill rolls for longitudinal rolling with a short mandrel (automatic, in particular tandem). This work is devoted to improving the shape of the rolls that form the caliber. Another concept of choosing the shape of the fillet successfully has tested in the design of two-roll round calibers with round releases. In this concept it was assumed a smooth connection of the fillet only with the release. The use of the proposed shape in the mill of longitudinal rolling allows to limit the possibility of metal pipe's flow during deformation into the gap between the rolls and, accordingly, to reduce the transverse diversity of the pipe. A method for calculating the geometric parameters of the caliber with a new shape has been developed. New calibration of rolls for longitudinally rolling mills with round caliber and round shape was successfully tested at the rolling mill 140 of OJSC "Interpipe Nico Tube".

Decomposition of micromotion at the head-neck interface in total hip arthroplasty during walking

Fretting corrosion as one of the leading causes for failure of modular hip prostheses has been associated with micromotion at head-neck taper junction. Decomposition of micromotion is helpful to promote the development of more realistic experiments investigating failure mechanisms of the head-neck junction in total hip arthroplasty. The aim of this study was to decompose the complex three-dimensional micromotion at the head-neck junction into multiple fundamental modes, including three translational and three rotational components. A three-dimensional finite element model composed of head-neck junction, liner and acetabular cup with a typical 12/14 taper size, as well as the taper mismatch of −4', was developed during walking. The analysis was divided into three procedures: a) the assembly simulation of the head and neck during surgery, b) verification with a simplified axisymmetric model, and c) three-dimensional modelling under normal walking. This study revealed that the main forms of micromotion contained circumferential, longitudinal micromotion and longitudinal rolling toggling, and were closely related to the state of motion. The maximum translational micromotion was predicted to be 10.9 μm during the walking gait, with the predominant modes of the circumferential translation of 9.6 μm, the longitudinal translation of 5.5 μm and the longitudinal rotation of 0.29° along the taper junction. These findings may provide design considerations for further experimental testing about fretting and facilitate the understanding of the fretting mechanisms in hip prostheses.