Extrusion Channel Research Articles

Analysis of Multi-angular Twist Channel Extrusion Technique for Processing AA2024 Aluminium Alloy

Analysis of Multi-angular Twist Channel Extrusion Technique for Processing AA2024 Aluminium Alloy

Stamping of Nonuniform Channels. 5. Calculation Methods for Channel Extrusion. 5.3. Extrusion of Hardening Materials

Stamping of Nonuniform Channels. 5. Calculation Methods for Channel Extrusion. 5.3. Extrusion of Hardening Materials

Influence of Strain Route Changes on the Microstructure and Mechanical Properties of CuZn36 Alloy during Cross Channel Extrusion CCE.

This study evaluates the impact of changing the deformation routes of the extrusion process in a cross-shaped die (CCE) on the structure and properties of a CuZn36 alloy (% at.). Samples with dimensions of Ø8 × 36 mm were subjected to extrusion at room temperature according to two variants: straight extrusion in the A route (2-, 4-, 8- and 12-pass) and extrusion with interoperative rotation by 90° in the BC route (2- and 4-pass). The improvement of strength properties was obtained as a result of grain fragmentation in the CCE process. Changes in the microstructure were observed using a light microscope, and mechanical properties were measured in the microhardness test and a static tensile test. The obtained results showed that the mechanical properties of the alloy depend on the number of passes and the material deformation route. This observation was related to the fragmentation of its structure and strengthening, which resulted in changes in its properties. The highest strength was characterized by the material pressed four times with the rotation of 90° (BC route), whose properties were comparable and even slightly better than the material squeezed twelve times without rotation (A route).

Joining of two similar PA-6 rods through equal channel angular press based Y-shape extrusion channel

• The present manuscript explores the scope of metal forming operations into a state of art joining procedure. • ECAP works on the principle of severe plastic deformation but still limited to laboratory tests. • Y-shape die channels overcome the limitation of punch load required in extrusion and ECAP methods. • Increase in coefficient of friction softens the polymer while higher punch load utilized for diffusion. In this study, a new technique for joining two PA-6 (polyamide) polymers is presented. The method employed to investigate the joining behaviour of plastically deformed polymers by the extrusion. The focus is on extrusion and equal channel angular pressing parameters such as punch load, joint structure, dynamic mechanical analysis, and X-ray diffraction of the joint polymer. The proposed Y-shape die channel is reliable to join two similar natures of polymers without using any additive materials, and hence product over-weighing can be avoided. Due to two similar PA-6 polymer rods, their welding compatibility is so high. Hence, polymer surface get fused when pressed at defined temperature and pressure through a constant die channel. From the results, it is found that the equal channel angular pressing results inhomogeneous plastic deformation as compared to the extrusion. The inhomogeneous flow of particles is only inside the extrusion channel. As the working temperature reaches 2/3rd of the polymer melting point, the required punch load is become lower than cold extrusion. The required punch load is well validated with analytical punch load. In the dynamic mechanical analysis, it is found that the storage modulus of the joint structure is comparatively higher than the base polymer. The crystallization of joint polymer is also observed by X-ray diffraction. At the end of the test, good quality of joint is formed and it is found that the Y-shape channel is an efficient die design to obtain deformation based joint structure.

Experimental studies and optimization of process variables in multi-angular twist extrusion (MATE) of Cu-Cr-Zr alloy

Researchers have recently interested in devising integrated severe plastic deformation (SPD) techniques that can create ultra-fine grained (UFG) metal in one pass. This paper proposes a novel integrated severe plastic technique called multi-angular twist channel extrusion (MATE). This technique was created the aim of retaining strain uniformity while applying a significant strain in a single pass. The input parameters such as annealing temperature, type of lubricant and ram speed, were optimized in this study in relation to the Vickers hardness, hardness inhomogeneity and ultimate tensile strength of the extruded material. Experiments were carried out based on full factorial design, and the TOPSIS approach was used to find the best combination of input parameters. The analysis of variance is used to determine the amount of contribution of input parameters on the mechanical properties. Finite element analysis was performed with the identified optimum parameter of annealing temperature = 550 °C, type of lubricant = MoS2 and ram speed = 3 mm/sec. The average effective strain of 2.72 is obtained by in the MATE process. Experimental studies revealed that the strength and hardness of copper alloy was increased by 69.8 % and 80.5 % respectively. Scanning electron microscope image revealed the grain refinement by MATE process in the copper alloy.

Stamping of Nonuniform Channels. 5. Calculation Methods for Channel Extrusion. 5.2. Extrusion of Nonhardening Materials

Stamping of Nonuniform Channels. 5. Calculation Methods for Channel Extrusion. 5.2. Extrusion of Nonhardening Materials

Stamping of Nonuniform Channels. 5. Calculation Methods for Channel Extrusion. 5.1. Formulas

Stamping of Nonuniform Channels. 5. Calculation Methods for Channel Extrusion. 5.1. Formulas

Stamping of Nonuniform Channels. 4. Deformed State of the Workpiece on Channel Extrusion. 4.3. Taking Account of Hardening

Stamping of Nonuniform Channels. 4. Deformed State of the Workpiece on Channel Extrusion. 4.3. Taking Account of Hardening

The effect of severe plastic deformation on the IF steel properties, evolution of structure and crystallographic texture after dual rolls equal channel extrusion deformation

This paper presents some results of the influence of severe plastic deformation on the microstructure evolution, grain refinement aspect, and mechanical properties of ultra-low carbon steel. Ti-stabilized experimental IF steel was deformed at a room temperature with unconventional SPD process—dual rolls equal channel extrusion (DRECE). Mechanical properties and structure of ferritic steel in initial state and after selected steps of deformation were investigated. The mechanical properties were determined by static tensile tests carried out at a room temperature and microhardness research. The structural investigations involved using scanning transmission electron microscopy observations, electron back scattered diffraction and measurements of the crystallographic texture. The DRECE process affects the evolution of the structure. The microstructural investigations revealed that the processed strips exhibited a dislocation cell and grain structures with mostly low angle grain boundaries. The electron backscattering diffraction (EBSD) examination showed that the processed microstructure is homogeneous along the strips thickness. The mechanical properties of the DRECE-processed IF steel strips increased with an increase the number of passes.

Stamping of Nonuniform Channels. 4. Deformed State of the Workpiece on Channel Extrusion. 4.2. Deformation under the End of the Punch

Stamping of Nonuniform Channels. 4. Deformed State of the Workpiece on Channel Extrusion. 4.2. Deformation under the End of the Punch

The influence of post-deformation annealing temperature on the mechanical properties of low-carbon ferritic steel deformed by the DRECE method

Abstract The paper presents observations on the mechanical properties characterizing low-carbon steel subjected to deformation by the dual rolls equal channel extrusion (DRECE) method and annealed for 60 min in different temperature variants in the range of 450–700°C. The DRECE process was carried out up to seven passes at ambient temperature. The investigations carried out revealed that the strength of the steel strips increases corresponding to the rise in the number of DRECE passes applied. The yield strength (YS) after seven passes is >2.5 times higher compared to the material in the initial state (before the deformation process). However, the tensile ductility decreased significantly after the DRECE. In order to obtain favorable mechanical properties, the steel strips were subjected to annealing. Our study demonstrates that after being processed by the DRECE method, low-carbon steel can be subjected to low-temperature annealing to ensure that it is endowed with high strength, while maintaining the characteristic good ductility of the material. The results of the research were analyzed in the context of an investigation into the microstructure change, assessed by scanning transmission electron microscopy (STEM), induced in low-carbon steel subjected to the DRECE process and low-temperature annealing.

Stamping of Nonuniform Channels. 4. Deformed State of the Workpiece on Channel Extrusion. 4.1. Deformation in the Region of Wall Formation

Stamping of Nonuniform Channels. 4. Deformed State of the Workpiece on Channel Extrusion. 4.1. Deformation in the Region of Wall Formation

Finite Element Model of Equal Channel Angular Extrusion of Ultra High Molecular Weight Polyethylene

Abstract Ultra-high molecular weight polyethylene (UHMWPE) used in biomedical applications, e.g., as a bearing surface in total joint arthroplasty, has to possess superior tribological properties, high mechanical strength, and toughness. Recently, equal channel angular extrusion (ECAE) was proposed as a processing method to introduce large shear strains to achieve higher molecular entanglement and superior mechanical properties of this material. Finite element analysis (FEA) can be utilized to evaluate the influence of important manufacturing parameters such as the extrusion rate, temperature, geometry of the die, back pressure, and friction effects. In this paper, we present efficient FEA models of ECAE for UHMWPE. Our studies demonstrate that the choice of the constitutive model is extremely important for the accuracy of numerical modeling predictions. Three considered material models (J2-Plasticity, Bergstrom-Boyce, and the three-network model) predict different extrusion loads, deformed shapes, and accumulated shear strain distributions. The work has also shown that the friction coefficient significantly influences the punch force and that the two-dimensional (2D) plane strain assumption can become inaccurate in the presence of friction between the billet and the extrusion channel. Additionally, a sharp corner in the die can lead to the formation of the so-called “dead zone” due to a portion of the material lodging into the corner and separating from the billet. Our study shows that the presence of this material in the corner substantially affects the extrusion force and the resulting distribution of accumulated shear strain within the billet.

Stamping of Nonuniform Channels. 3. Forces and Shape Changes in Channel Extrusion. 3.2. Determining the Extrusion Force, Maximum Wall Pressure, and Wall Height

Stamping of Nonuniform Channels. 3. Forces and Shape Changes in Channel Extrusion. 3.2. Determining the Extrusion Force, Maximum Wall Pressure, and Wall Height

Stamping of Nonuniform Channels. 3. Forces and Shape Changes in Channel Extrusion. 3.1. Kinematic and Stress State of Workpiece

Stamping of Nonuniform Channels. 3. Forces and Shape Changes in Channel Extrusion. 3.1. Kinematic and Stress State of Workpiece

Dual rolls equal channel extrusion as unconventional SPD process of the ultralow-carbon steel: finite element simulation, experimental investigations and microstructural analysis

The paper presents results of FEM modelling as well as properties and microstructure of the ultralow-carbon ferritic steel after the unconventional SPD process—DRECE (dual rolls equal channel extrusion). Based on the conducted numerical simulation information about the deformation behaviour of a steel strip during the DRECE process was obtained. The simulation results were experimentally verified. The influence of DRECE process on hardness distribution, fracture behaviour and microstructure evolution of the investigated steel was analysed. The increase of steel strength properties after subsequent deformation passes was confirmed. The microstructural investigations revealed that the processed strips exhibit the dislocation cell microstructure and subgrains with mostly low-angle grain boundaries. The grains after processing had relatively high dislocation density and intense microband formation was observed. It was also proved that this unconventional SPD method fosters high grain refinement.

Study of HCAP-PC to Enhance Process Efficiency for Age-Hardened Aluminum Alloys Based on Grey Relational Analysis

A multi-pass equal-channel angular pressing (helical channel angular pressing-parallel channel, HCAP-PC) is proposed to enhance process efficiency and avoid plastic deformation damage during the preparation of ultrafine-grained age hardened aluminum alloys. Multiple shear and twist deformations are provided at the single extrusion channel. The channel parameters were optimized by using grey relational analysis (GRA). An orthogonal L16-4-5 test array containing five factors (ψ, ϕ, γ, m and the length of L1 section) and four levels was collected to investigate the influence of channel parameters on the effective strain, the effective stress, the amount of damage and the deformation homogeneity coefficients. Based on the GRA, the grey relational coefficients and the grey relational grades were calculated to report the significant channel parameters which affect the extrusion quality and efficiency. Furthermore, according to the results of segregated grey relational grades, the contribution orders from high to low were listed as ψ, ϕ, γ, m and L1. The extrusion experiments were carried out with aluminum alloy 2024 after solid solution treatment and at the HCAP-PC die with geometry of ψ 20°, ϕ 90°, γ 73°, m 1.35 and 1d. The ultrafine-grained age hardened aluminum alloys were prepared and the process time was decreased to less than 120 min.

A 3D Printed Morphing Nozzle to Control Fiber Orientation during Composite Additive Manufacturing

AbstractFiber‐filled composite materials offer a unique pathway to enable new functionalities for systems built via extrusion‐based additive manufacturing (or “3D printing”); however, challenges remain in controlling the fiber orientations that govern ultimate performance. In this work, a multi‐material, shape‐changing nozzle—constructed by means of PolyJet 3D printing—is presented that allows for the spatial distribution of short fibers embedded in polymer matrices to be modulated on demand throughout extrusion‐based deposition processes. Specifically, the nozzle comprises flexible bladders that can be inflated pneumatically to alter the geometry of the material extrusion channel from a straight to a converging–diverging configuration, and in turn, the directional orientation of fibers within printed filaments. Experimental results for printing carbon microfiber‐hydrogel composites reveal that increasing the nozzle actuation pressure from 0 to 100 kPa reduced the proportion of aligned fibers, and notably, prompted a transition from anisotropic to isotropic water‐induced swelling properties (i.e., the ratio of transverse to longitudinal swelling strain decreased from 1.73 ± 0.37 to 0.93 ± 0.39, respectively). In addition, dynamically varying the nozzle geometry during the extrusion of continuous composite filaments effects distinct swelling behaviors in adjacent regions, suggesting potential utility of the presented approach for emerging “4D printing” applications.

Stretching Effect on Resistive Switching of TiO2/ZnO n–n Heterojunction Films

In this study, the switching characteristics of the GaIn/ZnO–TiO2/AgNWs devices under mechanical stretching conditions are investigated. It is shown that the maximum ON/OFF ratio of the unstretched sample is above 103, which exhibits reversible bipolar resistive switching. Upon stretching, the device ON/OFF ratio deteriorates by 1 order of magnitude. The switching mechanism can be ascribed to the formation/rupture of oxygen vacancy filaments. Finite element analysis demonstrates that the mechanical fatigue under repetitive stretching can be explained by the channel extrusion cracks and ductile failure with local necking at the interface. The microcracks may act as blocking layers, which limit the migration of the electrons and holes. Moreover, oxygen can easily get into the cracks, leading to the acceleration of the interfacial filament oxidation and decreasing the oxygen vacancy density. The interfacial adhesion and extrusion cracks may thus lead to the deterioration of switching performance. Our work may provide an approach to understand how to improve switching performance for the n–n heterojunction under stretching conditions.

Microstructure and Mechanical Properties of AM60 Magnesium Alloy Processed by a New Severe Plastic Deformation Technique

The mechanical properties and microstructure of AM60 Magnesium alloy processed by a new cyclic extrusion channel angular pressing (CECAP) technique were investigated in this research. In this novel method, a low extrusion ratio stage was added at the end of the CECAP process to enhance the hydrostatic stresses and equivalent strain. The structure was refined from the average grain size of ~ 76 µm for the annealed samples to 2.63 µm in the new CECAP after four passes. While for the CECAP and ECAP processes, it was 3.43 and 6.98 µm, respectively. Experimental results of the proposed CECAP process showed an improvement in the mechanical properties after the second pass that were stopped for the ECAP process. However, the hardness of the CECAP-processed and proposed samples was constantly increasing. This increase in hardness was 196% and 175% for the proposed CECAP and CECAP processes after four passes compared to the unprocessed sample, respectively. Moreover, the compressive yield stress and ultimate compressive strength of the CECAP-processed samples were higher in all passes; however, they were smaller than those of the proposed CECAP process. The hydrostatic compressive stresses and higher plastic strain in the proposed technique helped in further refining of the grains, which can effectively improve the mechanical properties.