Combined Extrusion Research Articles

A new severe plastic deformation technique of combined extrusion and torsion to prepare bulk ultrafine grained copper

Reducing grain size is a well-established method for strengthening metals. In this study, a novel severe plastic deformation technique—combined extrusion and torsion (CET) with composite strain—was developed to fabricate bulk ultrafine grained metals. A single pass of CET treatment (with a rotation velocity of 1 r/s and extrusion speed of 3 mm/s) refined coarse-grained copper from 54 μm to 450 nm at room temperature, resulting a significant increase in hardness from 0.55 GPa to 1.3 GPa. The CET technique addresses the limitations of conventional extrusion-processed copper (without torsion), which suffers from gradient microstructure and hardness distribution. It provides enhanced strain accumulation under the same extrusion ratio conditions. The more homogeneous microstructures and properties of CET-processed copper rods are attributed to the reduced strain gradient due to torsion. Additionally, targeted finite element analysis indicated that the CET technology requires 37 % less extrusion load and offers at least 30 % more strain compared to conventional extrusion methods. Compared with other severe plastic deformation methods, such as equal channel angular pressing and high-pressure torsion, which involve simpler deformation processes, the CET technique shows considerable promise for large-scale manufacturing of ultrafine-grained metals.

Analysis of extrusion characterization of Nd-Fe-B permanent magnet ring based on Normalized Cockcroft & Latham fracture criterion

The hot deformation behavior of hot-pressed Nd-Fe-B material was investigated using a Gleeble-3500 thermal simulation machine, with deformation of 50 %, temperatures ranging from 700 to 850 °C, and strain rates ranging from 0.01 to 1 s−1. A hyperbolic sine model was employed to establish a constitutive equation suitable for this material. In addition, the chosen fracture criterion and damage threshold in the simulations were validated against the experimental results. Then, a three-dimensional thermo-mechanical coupled model was developed to simulate the damage evolution of the material during the extrusion process. The effects of different extrusion processes and positions of the back pressure tool on the magnetic performance and forming quality of the material were investigated. The simulation results indicate that both the combined extrusion process and the back pressure tool located at the half of the workpiece will contribute to improve the uniformity of the magnetic properties, and effectively ensuring the regularity of the forming process at the top of the magnetic ring and suppressing the occurrence of cracks. The results of this paper will help to a better understanding of the deformation mechanism of Nd-Fe-B permanent magnet and provide a valuable theoretical guidance for the preparation of high-performance Nd-Fe-B magnetic rings.

Investigation of hot combined extrusion of steel hollow conical parts

Investigation of hot combined extrusion of steel hollow conical parts

A novel combined extrusion process of thin-walled tubular part with protrusion

A novel combined extrusion process of thin-walled tubular part with protrusion

Improving the tension-compression asymmetry of ZK61 magnesium alloy through texture optimization in combined extrusion

In order to improve the tension-compression asymmetry that exists widely in extruded magnesium alloys, ZK61 magnesium alloys with different texture characteristics were prepared by conventional extrusion, compression-extrusion, and cyclic extrusion compression. The effect of texture on the tension-compression asymmetry and associated deformation mechanisms of magnesium alloys was revealed based on the Sachs assumption. Subsequently, a texture-modified Hall-Petch relationship was used to quantify the combined effect of texture and grain on both tensile and compressive yield strengths. It is found that the slight weakening of the {0002}∥LD fiber texture was beneficial to the suppression of {10‐12} twinning and the activation of prismatic slip, which in turn significantly improved the tension-compression asymmetry without the obvious sacrifice of strength. However, excessive texture inclining can cause a striking decrease in strengths and even reverse tension-compression asymmetry due to the activation of basal slip and pyramidal slip. In conclusion, slight basal texture weakening was a texture optimization strategy to obtain tension-compression symmetry and high strength for wrought magnesium alloys.

Selection of Design Scheme for an Ultrahigh-Pressure Hydrostatic Extrusion Cylinder

In this study, the mechanical models of a multilayer combined extrusion cylinder and a steel-wire-winding extrusion cylinder were established and compared using a finite element simulation and existing experimental cases. This work provides theoretical support for the selection of an ultrahigh-pressure extrusion cylinder. Comparative analysis of an ultrahigh-pressure extrusion structure was carried out. The mathematical optimization model is established based on the mechanical model, and the ultimate bearing capacities of the schemes are compared. Additionally, the winding mode and the number of core layers of the extrusion cylinder are compared and analyzed, which provides a theoretical basis for the parameter design of the steel-wire-winding ultrahigh-pressure extrusion cylinder. This work holds good theoretical significance and practical value for the promotion and application of ultrahigh-pressure hydrostatic extrusion technology.

Bioactive Zn-0.6Cu thin sheet for craniofacial bone repair: In vitro and in vivo evaluations

Millions of craniofacial surgeries are performed annually worldwide, and materials for craniofacial bone repair are widely needed. However, traditionally applied materials, such as titanium and polymethylmethacrylate, have some shortcomings (limited malleability, material-based toxicity, non-biodegradability, lack of bioactivity, etc.). Zinc based biodegradable metals possess superior mechanical properties, biodegradability, and bioactivity, which make them promising candidate materials. Here, we successfully fabricated Zn-0.6Cu thin sheets (thickness ≤0.5 mm, suitable for craniofacial surgery) through combined extrusion and rolling. The in vitro and in vivo performances were generally evaluated and compared to those of a commercially applied pure titanium mesh. The mechanical properties of Zn-0.6Cu sheets were superior to those of clinically used polymethyl methacrylate. They were easy to shape and would not fracture during deformation. The Zn-0.6Cu sheet exhibited a gentle degradation mode, and proper implant-derived Zn improved osteogenic differentiation of rat bone marrow mesenchymal stem cells by up-regulating expression of osteogenesis related genes (alkaline phosphatase, bone morphogenetic protein-2). Thus, it further promoted extracellular matrix mineralization by improving calcium deposition for bone formation. It also improved the expression of angiogenesis-related genes (vascular endothelial growth factor, hypoxia-inducible factor alpha). The Zn-0.6Cu sheet exhibited high osteogenic activity in a cranial defect animal model compared to a non-biodegradable pure titanium mesh. Significant surface degradation occurred after two months in vivo, and degradation products were compatible with surrounding tissues. In general, the Zn-0.6Cu thin sheet seems to be a bioactive material selection for craniofacial bone repair, which might possibly accelerate defect repair and prevent adverse complications.

COMBINED EXTRUSION OF GLASSES WITH A CONICAL BOTTOM. EXPERIMENTAL VERIFICATION OF THEORETICAL FORMULAS IN COMBINED EXTRUSION

Cold combined extrusion of cups with a conical bottom part made of a hardening material is considered. The methods for performing specific calculations of the deforming force for various geometric parameters of free and constrained extrusion are demonstrated in detail. Comparison with the experimental data obtained during the extrusion of aluminum alloy AD1 shows the high accuracy of the derived calculation formulas. It is confirmed that for most of the working stroke, the force of the combined extrusion will be significantly less than the force of the traditional extrusion.

COMBINED EXTRUSION OF GLASSES WITH A CONICAL BOTTOM PRODUCTION TESTS OF COMBINED EXTRUSION

The production testing of cold combined extrusion of glasses with a conical bottom part made of steel 12KH18N9T is considered. Preliminary technological calculations with the help of previously developed methods are demonstrated in detail. Production tests confirmed the high accuracy of the derived calculation formulas and the suitability of the developed methods for designing production technological processes.

Grid Dependency of Severe Plastic Deformation during Combined Extrusion and Forging Process

Plastic deformation during the metal forming process involves very distinctive behavior of parameters, which results in complicated mathematical modelling to estimate the forming load. As the complexity of the shape increase, the determination of forming (punch) load becomes intricate. In this context, the present work cover parameters influencing the grid independency on forming load during combined extrusion and forging of single collar collet chuck holder which is predicted followed by validation with experimental results. It can be observed from the numerical analysis that the grid dependency on the ram velocities shows a negligible effect whereas friction factor ensued a fragile variation.

Effect of l-cysteine and l-ascorbic acid addition on properties of meat analogues

Currently, studies are underway to use pea protein isolate (PPI) for the production of meat analogues because it is considered as a more sustainable alternative to soy. The potential of PPI has been demonstrated in extrusion and PPI in combination with wheat gluten has been studied in the shear cell. To enlarge the possibilities to make meat analogues with a broader range of properties, the effects of l -cysteine (CYS) and l -ascorbic acid (AA) on PPI and wheat gluten (WG) blends were examined at different concentrations (0, 100, 500, 1000 and 2000 ppm). The results showed that both CYS and AA altered the properties of the products formed by the high-temperature shear cell (HTSC). Both additives altered the fibrousness and the mechanical properties of the products obtained after processing. Especially CYS revealed an increase in tensile stress, tensile strain and Young's modulus as its concentration increased. However, products containing CYS depicted a relatively stable anisotropic index of 1, which corresponded to a densely packed matrix that was observed by microstructural analysis. A small elevated anisotropic index (>1) of products containing AA at concentrations of 500–2000 ppm could be attributed to the formation of pores parallel to the shear flow direction in these samples visualized by a confocal laser scanning microscope (CLSM) and the scanning electron microscope (SEM). In the products containing 2000 ppm of AA and 2000 ppm CYS, small and large fibers were formed, respectively. Therefore, this research pointed out the potential application of CYS and AA to alter and control the textural attributes of products. This application could aid in improving the consumer acceptance of meat analogues and, thus, contribute to being able to feed the increasing population of the world. • l -cysteine and l -ascorbic acid were examined for the production of meat analogue. • They altered properties of products formed by high-temperature shear cell. • l -cysteine increased tensile stress, tensile strain and Young's modulus of products. • l -ascorbic acid increased the browning index, fiber formation and anisotropy index.

The development of triangular kinematic module to calculate the deformation pressure in the extrusion processes

Аliieva L. І., Levchenko V. M., Aliiev I. S., Kartamyshev D. O. The development of triangular kinematic module to calculate the deformation pressure in the extrusion processes
 The article presents the universal kinematic module developed on the basis of the energy upper bound method, designed for use in mathematical simulations of combined processes of cold forging. In particular, this module can be used for force regime simulating and tool loads analyzing at radial-forward extrusion of hollow products with blind hole of continuous workpieces to describe deformation zones during metal flow to the center and turn zones from radial flow to backward one. The kinematically possible velocity field for convex curvilinear (parabolic) triangular module and the equations of its parabolic inclined boundary are given. Analytical dependencies for power of deformation forces, friction and shear at the boundaries of the module, as well as for the reduced pressure in a parametric form are obtained. The developed curvilinear kinematic module, the use of which makes it possible to increase the efficiency of the upper bound method for studying the processes of combined extrusion, has been tested and described. It is shown that value of reduced pressure for the curvilinear turn module is most affected by the relative thickness of the flange, its radius, the thickness of the wall of the tubular workpiece, as well as friction conditions. The possibility of correct using of curvilinear triangular module for the analysis of complex schemes of processes with several zones is demonstrated. The simulation for calculation schemes of radial-forward workpiece extrusion with variable flange height was carried out. It has been determined that the developed curvilinear triangular module due to the reducing the value of the velocity jump at its boundaries, makes it possible to reduce the upper estimate of the tool loads in comparison with the variants of simulations that were previously based on rectangular modules.

A combined extrusion, retrogradation, and cross-linking strategy for preparing starch-based straws with desirable mechanical properties

This work developed a novel strategy for producing starch straws with desirable mechanical properties by a combination of extrusion, retrogradation, and sodium trimetaphosphate (STMP) cross-linking. The straws were prepared by first extruding starch, glycerin, and water (10:1:1) with a double screw extruder, then retrograding the resulting straws at 4 °C for 6 h, and finally cross-linking the straws. Rapid visco-analyzer profiles showed decreases in the viscosity of milled straws with increases in the cross-linking duration, perhaps reflecting a higher degree of crosslinking. Fourier transform infrared spectroscopy showed evidence of more hydrogen bonds in the straws with a longer cross-linking duration, while thermogravimetric analysis indicated higher thermal stability for the cross-linked straws than for the controls. The straw cross-linked for 3 h showed 1.52 times higher stiffness after soaking in room-temperature water for 30 min (4967.56 g/s), and 1.88 times higher stiffness after soaking in 60 °C hot water for 5 min (5371.89 g/s) than the original straw. STMP cross-linking also improved the starch straw mechanical properties after soaking in common soft drinks. These findings identify a potential new way to produce biodegradable straws with desirable properties from starch, an affordable biomaterial, while also addressing the problem of petroleum-based plastic pollution.

Development of a pea protein‐/chitosan‐based bioactive film using Aronia melanocarpa polyphenols as a bioactive ingredient

AbstractThe study was designed to develop a pea protein‐ (PP) and chitosan (CS)‐based bioactive composite film using purified Aronia melanocarpa polyphenols (AMP) as a bioactive ingredient (PP‐CS‐AMP). First, AMP was extracted and purified, and the antioxidant properties of AMP were tested, and the result indicated that AMP showed stronger antioxidant properties than vitamin C (Vc). Second, five kinds of PP‐CS film were developed: PP including unextruded pea protein (NEP), extrusion pea protein (EP), papain co‐extruded pea protein (PEP), neutral protease co‐extruded pea protein (NPEP), and double enzyme combined extrusion pea protein (DCEP). The five kinds of PP‐CS film were characterized and evaluated for various functions and properties; principal component analysis and membership evaluation were used to analyze the comprehensive scores of the films. It was observed that the NPEP‐CS film obtained the highest score. Extrusion and enzyme extrusion treatments improved the structure and properties of PP, and therefore enhanced the properties of PP‐CS film. Finally, NPEP‐CS‐AMP film was developed (AMP content 0, 4.0% and 8.0%, w/v) and tested for their performance, and the results suggested that the addition of 4.0% AMP gives the NPEP‐CS‐AMP film excellent physical and antioxidant properties.Novelty impact statement Aronia melanocarpa polyphenols (AMP), as a bioactivity ingredient was firstly incorporated into pea protein (PP) ‐ chitosan (CS) film. Extrusion and enzyme extrusion can improve the structure and properties of PP, which is beneficial to improvement on the properties of PP‐CS film. NPEP‐CS‐AMP film exhibit excellent physical properties, structural performance and high antioxidant activity.

Investigation the structure and properties of deformed semi-finished products produced from chips of Al–Mg alloys system alloyed with scandium

The article presents the results of studies that make it possible to solve the problem of processing secondary waste from expensive aluminum alloys without irretrievable loss of metal. For this purpose, tasks were set and solved for the development of technological schemes for obtaining longish deformed semi-finished products from chip waste of Al–Mg alloys 01570 and 1580 alloyed with scandium using methods of powder metallurgy and metal forming. For their experimental verification, the operations of chip briquetting, combined rolling-extrusion (continuous extrusion), sectional rolling, hot extrusion and drawing in combination with heat treatment were applied. According to these schemes, semi-finished products in the form of rods and wires were obtained. Structure and mechanical properties were investigated. It has been revealed that when hot-extruded rods are obtained from chip briquettes of alloy 01570 on a vertical hydraulic press, even with significant degrees of deformation during extrusion, the margin of plastic properties is small and makes it possible to obtain a wire with a diameter of only 4.2 mm after drawing. The processing of briquettes from 1580 alloy chips using the combined rolling-extrusion method makes it possible to obtain after cold deformation a wire with a diameter of up to 3 mm. At the same time, the influence of the annealing process on the structure and properties of deformed semi-finished products from the investigated alloys was studied. It is shown that due to the low plasticity of the investigated material cold working of the rods must be carried out with small degrees of deformation, alternating it with intermediate annealing according to the proposed regime. An analysis of the physical and mechanical properties of the wire obtained using combined processing showed that its strength and plastic properties are comparable to the properties of the wire obtained from a cast billet, and the structure is characterized by a high degree of elaboration and compactness. Thus, as a result of the research, technological schemes have been developed and processing parameters have been determined for the production of rods and wire from graded chip waste of alloys 01570 and 1580 using compaction, discrete and continuous extrusion, as well as cold drawing.

Solid-state extrusion of polymers using simple shear deformation

Abstract The review considers the possibilities of new methods of solid-state extrusion of polymers based on the use of deformation schemes that include simple shear - equal-channel angular extrusion, equal-channel multi-angle extrusion and combined extrusion. Information on the evolution of the physico-mechanical properties of glassy, semi-crystalline polymers, polymer blends and composites is given.

Estimating the initial stage in the process of radial-reverse extrusion using a triangular kinematic module

Those parts of solid or hollow blanks whose shape is complex should be produced by means of combined radial-longitudinal extrusion. However, the use of combined extrusion processes with several degrees of flow freedom requires a preliminary assessment of shape formation, which is true, taking into consideration the peculiarities of evolution of strain sites at different stages of deformation. When deforming high blanks, the presence of an intermediate rigid zone can be observed, separating two autonomous strain sites. When constructing an estimation scheme of the initial stage of the process of combined radial-backward extrusion of hollow parts with a flange, the presence of an intermediate rigid zone is taken into consideration. The need to improve the devised estimation scheme is caused by significant deviations in the projected growths of a part from its experimentally derived dimensions. As an alternative to the axial rectangular kinematic module of the lower deformation site, the use of an axial triangular module has been proposed, whose effectiveness is demonstrated in simulating the process of radial-longitudinal extrusion with expansion. The rationality of the proposed replacement was revealed, both for forecasting the forced mode of the deformation process and for the gradual part’s shape formation. This has made it possible to reduce the projected estimates to 10 % in terms of the increase in the size of a part based on a comparative analysis with experimentally derived data. It is recommended to use the devised scheme for modeling the initial stage of the process for relatively high blanks at H0/h1>4…6; the limitation is the degeneration of the intermediate rigid zone. This will contribute to compiling recommendations for expanding the possibilities of using combined radial-backward extrusion of hollow parts with a flange during production

Optimization of the Steady Combined Forward and Backward Extrusion Test for Higher Sensitivity to Friction in Cold Forging

To improve the sensitivity of the steady combined forward and backward extrusion test proposed in previous work, an optimization job based on the finite element simulations was carried out. A raw material of 0.45% carbon steel was tested under different stain rates from 0.001s-1 to 1s-1 and different temperatures from 30°C to 400°C, and the material flow stresses were modelled by Hensel-Spittel equation. The deformation degree of the forward extrusion was set as 50%. The key parameters including the deformation degree of the backward extrusion, the ratio between the radius of the punch nose and the radius of the punch, the taper angle of the punch, the die angle, the sizing lands of the punch and the die were optimized. The sensitivity of the optimal design is improved about 20% compared with previous design when the friction factor is assumed as 0.03~0.15. The new group of calibration curves presents more scatter than the old group. The sensitivity improvement is also validated by the experimental works.

COMBINED EXTRUSION OF GLASSES WITH A CONICAL BOTTOM. METHODOLOGY FOR CALCULATING TECHNOLOGICAL PARAMETERS TAKING INTO ACCOUNT THE TEMPERATURE EFFECT OF DEFORMATION

The methodology for calculating the energy-force and deformation parameters of the process of constrained combined extrusion of glasses with a conical bottom taking into account the temperature effect of deformation is presented. In the latter case, the account of the hardening of the extruded material is described in detail. The above formulas allow us to determine such important parameters of the stamping process as total and specific deforming force, maximum pressure on the die wall, and an increase in the yield stress.

COMBINED EXTRUSION OF GLASSES WITH A CONICAL BOTTOM. METHODOLOGY FOR CALCULATING TECHNOLOGICAL PARAMETERS AT INITIAL DEFORMATION BY CONSTRAINED COMBINED EXTRUSION

The methodology for calculating the energy-force and deformation parameters of the process of constrained combined extrusion of glasses with a conical bottom is presented. The extrusion of both non-hardening and hardening material is considered. In the latter case, the account of the hardening of the extruded material is described in detail. The above formulas allow us to determine such important parameters of the stamping process as total and specific deforming force, maximum pressure on the die wall, and an increase in the yield stress.