Twist Extrusion Research Articles

Tensile strength and strain energy absorption in twist extruded Al 6061-B4Cp metal matrix composites

ABSTRACT Due to its accessibility and ease of use in various sectors, the twist extrusion method is gaining significant acceptance for improving the strength and hardness of structural components. However, only a few experiments on twist-extruded MMCs of aluminium 6061 alloy reinforced with ceramic boron carbide (B4C) particles have been reported. The development of an Al-6061 alloy reinforced with 1.5–8 weight percent B4C particles and its twist extrusion, a severe plastic deformation method, are the main subject of this work. The study aimed to investigate the influence of particles and the extrusion process on the tensile strength and specific strain energy absorption of both the matrix and the composites. It was observed that the addition of B4C particles and the extrusion process increased the hardness and tensile strength of the alloy by 29.1% and 68.3%, respectively and for the composites with 8 wt.% particles, the increases were 31.8% and 62%, respectively. However, the theoretical density, ductility and absorbed strain energy decreased by 3.97%, 35.7%, and 27.9%, respectively, for the composite with 8% B4C, compared to the extruded matrix. A microscopic study determined the ASTM grain size number, which supported the observed physical and mechanical properties of both the as-cast and twist-extruded Al 6061-B4Cp composites.

KEARNS TEXTURE PARAMETERS AND PROPERTIES OF HEXAGONAL MONO- AND POLYCRYSTALS

Problem statement. Polycrystals' physical and mechanical properties are determined by the corresponding properties of single crystals (crystallites) that make up the polycrystal, and their distribution by orientation in the polycrystal (texture). In metals with a hexagonal structure, the use of Kearns texture parameters, which show the degree of coincidence of the hexagonal axis of crystallites with a given direction in a polycrystalline sample, allows determining the property of a polycrystal in this direction, if the properties of a single crystal in the direction of its hexagonal axis and the perpendicular direction are known. It is also possible to solve the inverse problem: determining the properties of a single crystal in the direction of its hexagonal axis and the perpendicular direction based on the properties of the polycrystal and the determined of the Kearns texture parameters. Materials and methods. Elastic and mechanical characteristics of hexagonal alloys based on titanium (Grade 1 and VT1-0) and magnesium (Mg − 10 % Li and ZE10) were studied after different types of deformation − rolling, alternating bending, and twist extrusion. The Kearns texture parameters were determined by the X-ray method based on the data of the construction of inverse pole figures (IPF) in the normal direction (ND) to the sheets plane and the rolling direction (RD). The results of the experiment. It is shown that the specified method allows to calculate the elastic and mechanical properties of the specified polycrystals after they undergo various types of deformation with an error of no more than 5−10 %, as well as to solve the inverse problem of calculating the properties of single crystals with an error of no more than 5 %. Conclusions. Using the parameters of the Cairns texture and the characteristics of single crystals of magnesium alloys ZE10, Mg 5 % Li, titanium Grade1 and VT1-0 made it possible to calculate the corresponding properties of polycrystals and their anisotropy. The use of Cairns texture parameters, experimental values of the modulus of elasticity, tensile strength and yield strength of polycrystalline sheets of the studied magnesium and titanium alloys made it possible to evaluate the characteristics. There are strong correlations between the values of the modulus of elasticity, the mechanical characteristics of the studied sheets of magnesium and titanium alloys, on the one hand, and the corresponding parameters of the Cairns texture, on the other hand.

Dislocation-Based Finite Element Modeling of an Off-Axis Twist Extrusion with Variable Helix Angles

Dislocation-Based Finite Element Modeling of an Off-Axis Twist Extrusion with Variable Helix Angles

Comparison of Linear and Nonlinear Twist Extrusion Processes with Crystal Plasticity Finite Element Analysis.

The mechanical characteristics of polycrystalline metallic materials are influenced significantly by various microstructural parameters, one of which is the grain size. Specifically, the strength and the toughness of polycrystalline metals exhibit enhancement as the grain size is reduced. Applying severe plastic deformations (SPDs) has a noticeable result in obtaining metallic materials with ultrafine-grained (UFG) microstructure. SPD, executed through conventional shaping methods like extrusion, plays a pivotal role in the evolution of the texture, which is closely related to the plastic behavior and ductility. A number of SPD processes have been developed to generate ultrafine-grained materials, each having a different shear deformation mechanism. Among these methods, linear twist extrusion (LTE) presents a non-uniform and non-monotonic form of severe plastic deformation, leading to significant shifts in the microstructure. Prior research demonstrates the capability of the LTE process to yield consistent, weak textures in pre-textured copper. However, limitations in production efficiency and the uneven distribution of grain refinement have curbed the widespread use of LTE in industrial settings. This has facilitated the development of an improved novel method, that surpasses the traditional approach, known as the nonlinear twist extrusion procedure (NLTE). The NLTE method innovatively adjusts the channel design of the mold within the twist section to mitigate strain reversal and the rotational movement of the workpiece, both of which have been identified as shortcomings of twist extrusion. Accurate anticipation of texture changes in SPD processes is essential for mold design and process parameter optimization. The performance of the proposed extrusion technique should still be studied. In this context, here, a single crystal (SC) of copper in billet form, passing through both LTE and NLTE, is analyzed, employing a rate-dependent crystal plasticity finite element (CPFE) framework. CPFE simulations were performed for both LTE and NLTE of SC copper specimens having <100> or <111> directions parallel to the extrusion direction initially. The texture evolution as well as the cross-sectional distribution of the stress and strain is studied in detail, and the performance of both processes is compared.

Design, Finite Element Analysis and Optimization of Helical Angular Pressing (HAP) Method as a Novel SPD Technique

Severe Plastic Deformation (SPD) processes improve the mechanical properties of materials by obtaining Ultra Fine Grained (UFG) materials, orienting the grains and reforming the grains. Helical Angular Pressing (HAP) is a newly proposed Severe Plastic Deformation (SPD) method. In order to improve the efficiency of the HAP method, its die geometry should be optimized first. In this context, four parameters (helical diameter, helical pitch, helical height and channel radius) were determined for the die channel geometry, each with four levels according to the literature. Then, thanks to Taguchi L16 combinations, 16 Finite Element Analyses (FEA) were carried out using Deform 3D software instead of 256 simulations, and effective strain values and maximum pressing load values were obtained. Later on, using the SPSS 16 software, Taguchi optimization was carried out to obtain the optimum HAP die channel geometries by minimizing the press load and maximizing the effective strain values. Next, the Finite Element Analysis (FEA) was repeated with these determined optimum die channel parameters. Finally, the efficiency of this novel HAP method was compared with conventional Equal Channel Angular Pressing (ECAP) and Twist Extrusion (TE) methods. As a result, HAP method provides effective strain values equivalent to 10 number of passes after processing with ECAP. And it is approximately 4 times higher than that achieved by TE processing. As a result of the Taguchi optimization, it is concluded that the values in the combination of diameter (d)=60 mm, height (h)=50 mm, radius (r)=4 and pitch (p)=1.25 are the optimum die geometry. In conclusion, these results indicate that the proposed novel HAP method is an efficient and applicable SPD technique.

Severe plastic deformation: A state of art

The proposed application of the study on severe plastic deformation (SPD), also known as Nano-SPD, is to provide a comprehensive overview of the recent advancements and developments in the field. The focus of the study is to highlight the various continuous processes used for producing ultrafine-grained and nanostructured materials, such as equal-channel angular pressing, high-pressure torsion, twist extrusion, accumulative roll-bonding, and multi-directional forging. The study also aims to demonstrate the versatility of SPD in processing a wide range of materials, including semiconductors, alloys, glasses, polymers, ceramics, and composite materials. Furthermore, the study highlights the potential of SPD in stabilizing metastable states and synthesizing novel materials with superior functional and mechanical characteristics. The proposed application of the study is to provide a comprehensive and up-to-date review of the advancements and developments in the field of Nano-SPD and to highlight its potential in producing advanced materials with enhanced properties. This study is expected to be useful for researchers, engineers, and material scientists working in the field of materials science and engineering.

Effect of multi-pass continuous screw twist extrusion process on microstructure evolution, texture, and mechanical properties of AZ31 magnesium alloy

Effect of multi-pass continuous screw twist extrusion process on microstructure evolution, texture, and mechanical properties of AZ31 magnesium alloy

Mechanical property improvement of a AA6082 alloy by the TV-CAP process as a novel SPD method

AbstractTwisted variable channel angular pressing (TV-CAP) is a novel method. While it combines the advantages of equal channel angular pressing (ECAP), twist extrusion and direct extrusions, also it eliminates the disadvantages of these methods. Finite element analysis was also carried out in order to examine the design parameters, material flow and examine the effective strain values. Hardness and tensile tests were performed to examine the effect of TV-CAP on the mechanical properties of AA6082. In addition, optic microscope, SEM and TEM images were taken respectively and XRD, EDS and EBSD analyses were accomplished in order to investigate the microstructural analysis. As a result of this study, it has been observed that the material has hardened approximately 3 times compared to the annealed material and became 1.5 times stronger in terms of ultimate tensile strength. It was also concluded that, this new method is more efficient than twist extrusion and multi-pass equal channel angular pressing processes.

Experimental–Numerical Study of the Effect of Per Pass Applied Strain on the Electrical and Mechanical Properties of Copper Samples in Twist Extrusion Process

Experimental–Numerical Study of the Effect of Per Pass Applied Strain on the Electrical and Mechanical Properties of Copper Samples in Twist Extrusion Process

Hydrostatic twist extrusion (HTE) for processing relatively long ultrafine grained samples

In this study, hydrostatic twist extrusion (HTE) has been introduced for processing relatively long ultrafine grained (UFG) bulk samples. By using high-pressure fluid surrounded the sample, surface contact between die and sample was eliminated. The high-pressure fluid causes high hydrostatic pressure, which leads to improvement of material properties and increased the aspect ratio of the sample (length/diameter). The HTE process was applied to commercial pure aluminum samples at room temperature, and then microstructure and mechanical properties were examined. The results demonstrate that after HTE process, the grain size was reduced from 54 µm to ∼800 nm, and microhardness was increased from 29.2 HV to 37.7 HV. Also, yield and ultimate strength were noticeably increased from 78 MPa and 103 MPa to 166 MPa and 175 MPa, respectively. This process seems to be very promising and interesting for the future industrial application.

Structure and Mechanical Properties of Titanium Processed by Twist Extrusion and Subsequent Rolling

The article considers one of the combined methods of severe plastic deformation (SPD), which includes twist extrusion (TE) and subsequent rolling. The use of combined forming methods is promising for industrial use. Titanium grade 1 was used as a material in the experiments. Rolling was carried out in three stages with a decrease in temperature from 350°C to 180°C for a number of passes with one heating. The accumulated strain degree was e = 4.6 at twist extrusion and e = 3 in rolling. Increasing the reduction per pass decreases the number of heatings and increases the efficiency of the rolling process in whole. At the same time, it is necessary to set the maximum processing modes at which recrystallization processes do not occur in the billet. When rolling, the deformation degree in one pass was taken in the range of 5–20% with an increase in successive passes. The use of such deformation degrees allowed reducing the grain size in titanium grade 1 significantly. Twist extrusion reduces the grain size to 300–500 nm. Subsequent rolling allowed reducing the size of structural elements to 50–100 nm and provided a significant increase in the mechanical characteristics of the billet material (up to 869 MPa) while maintaining satisfactory ductility (up to 11.6%). It was found that increasing the deformation degree in one pass up to 40% at cross-rolling and simultaneously increasing the temperature to 385°C led to a decrease in the UFG structure quality and reduced strength of the deformable material by starting the dynamic recrystallization process.

An analysis of crystallographic texture and residual stresses of aluminium alloy RSA-501 after selected processes of twist extrusion (TE)

This study presents the residual stress analysis for the twist extrusion (TE) process after the experiment and numerical simulation and the analysis of the crystallographic texture changes and changes in hardness before and after the TE process for an RSA-501 aluminium alloy (Al; Mg5%; Mn1.5%; Sc0.8%; Zr0.4%).Crystallographic textures were obtained with the PANAlytical Empyrean X-ray diffractometer. The stresses were measured by applying the X-ray method with the use of using the PROTO iXRD diffractometer.The use of severe plastic deformation processes in the mass of the material leads to a significant change difference in the stress distribution in the workpiece and a change in texture compared to the reference material. The stress distribution in the sample cross-section and stress values varied and depended on the stage of the twisting process to which the surface was subjected. The highest stress (about 600 MPa) appears at the peaks of the front surface when exiting the twist area die TE. Higher stress values at the edges of the specimen are caused by friction (deformation) of the material against the die surface. The TE process strengthened the highest crystallographic texture background level was 49%.The conducted tests and the obtained results allow the determination of the process parameters and critical areas of the sample by carrying out a numerical simulation.Microhardness increases due to the TE process and the largest values were observed at the edges. This phenomenon is confirmed by the numerical simulation results presented in this paper.

Comprehensive improvement of strength and ductility in CLAM steel subjected to TEU: The role of heterogeneous microstructure

To improve the comprehensive properties of CLAM steel and expecting good performance in service conditions, twist extrusion and upsetting (TEU) based thermo-mechanical treatment (TMT) was introduced into the steel at 600 °C, 670 °C, and 740 °C. Optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) was used to characterize the microstructural evolution during the deformation. Uniaxial tension test was used to evaluate the tensile mechanical property. The results show that the grain size and dislocation density of the processed samples decrease from the as-received condition, but are higher than that in the as-tempered conditions. The particle sizes of M23C6 and MX in the TEUed samples are lower than that in the as-tempered case, which contribute a lot to the yield strength. The yield strength of the TEUed CLAM steel decrease with the increase of deformation temperature and a good match in strength and ductility, relating to heterogeneous microstructure, has been achieved at the deformation temperature of 670 °C (yield stress: 853.59 MPa, ultimate tensile stress: 992.4 MPa, elongation: 15.7%). The K value and exponent in the Hall-Petch relationship should be modified owing to the volume fraction of martensite, which is harder than ferrite and causes interface elastic mismatch stress, is different at different temperatures.

Influence of twist extrusion and thermal action on texturing and properties of titanium

Influence of twist extrusion and thermal action on texturing and properties of titanium

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.

Grain Structure Evolution and Mechanical Properties of Multi-Channel Spiral Twist Extruded AA5083

This study presents a comprehensive evaluation of the effects of multi-channel spiral twist extrusion (MCSTE) processing on the mechanical properties and structural evolution of AA5083. The structural evolution and texture developed were mapped by electron backscatter diffraction (EBSD) for three successive passes and compared with an as-annealed plate. An evaluation of the hardness and tensile properties was presented and correlated with the EBSD findings. The displayed EBSD results revealed that grain refinement was strongly associated with the presence of a high density of low-angle grain boundaries (LAGBs) after one pass, which developed into fine grains of less than 20 μm and high-angle grain boundaries (HAGBs) after three MCSTE passes. The three pass processing led to a 65% reduction in grain size. This reduction in grain size was coupled with an enhancement in the hardness and tensile properties. Additionally, the crystallographic texture study represented a slightly random texture due to the presence of intermetallic particles in AA5083. This study demonstrates the efficacy of MCSTE as a grain refinement tool.

An investigation on twist extrusion followed by forward extrusion in production of aluminum–copper bimetallic bar

In this research, the feasibility of making aluminum–copper bimetallic bar by twist extrusion followed by forward extrusion is addressed. In this consecutive process, twist extrusion was used in several passes and its effect was investigated on the bond strength between aluminum and copper as well as the mechanical properties of the produced bimetallic bars. When forward extrusion was the only applied process, the compressive yield and shear bond strength of produced bimetallic bars were 184MPa and 5.4MPa, respectively. Applying four twist extrusion passes followed by one forward extrusion pass increased these values such that the compressive yield and shear bond strength were increased by about 64% and 200%, respectively. The hardness was also significantly increased by the utilization of this procedure. Microstructures of copper and aluminum in the produced bars showed that by applying and repetition of the twist extrusion, the grain size was reduced. The Mechanical locking was the main factor in bond formation. Reducing the gap between the metal plates at the interface and increasing the joint fraction improved the shear bond strength.

非線形ねじり押出法による銅単結晶の組織変化

非線形ねじり押出法による銅単結晶の組織変化

Tailoring twist extrusion process; the better strain behavior at the lower required loads

This study dealt with discovering the optimal conditions of the twist extrusion parameters for producing materials possess enhanced strain behavior with the least amount of extrusion load. It was found that the twist angle has a dominant influence on the strain behavior of the deformed sample with the contribution percentage of 56%, while the effect of friction coefficient would be the most noticeable if the required extrusion load is considered. Based on above, pure copper with the square cross-section was subjected to the process with the large twist angle at the best lubricant state. The results showed that the strength and hardness of the deformed copper were considerably enhanced compared to the initial condition due to the substantial grain refinement. The uniform plastic deformation zone of the deformed sample is limited which causes the reduction of strain-hardening exponent and ductility. Moreover, the lateral region of the sample’s cross-section endures larger plastic strain compared to the central one, leading to owning higher hardness. A combined microstructure consisting of low angle dislocation walls and high angle grain boundaries was also determined for the deformed copper.

Experimental studies on magnesium metal matrix composites processed by Twist Extrusion

Recently magnesium alloys and magnesium composite were widely used due to their good strength to weight ratio. These materials find its applications in the bio-medical and in aviation industries. The aim of this study is to twist extrude the hybrid magnesium composite. The magnesium AZ91 alloy is used matrix medium and it was reinforced with 2%SiC and 1.5% B4C. The twist extrusion was carried out in a split die with a slope angle of 54°. The composite is prepared by the bottom pouring method. The number of passes is limited to one, as adding the reinforcement increases the brittleness of the composites. The twist extrusion of the composite resulted in a porosity free sample. Hardness was measured by Macro-Vickers tester and ASTM A370 standard was used for the tensile test. Results indicate an increase 26.6% in strength and 38.5% hardness of the twist extruded composite.