Equal Channel Angular Extrusion Process Research Articles

Numerical Simulation of Al 6062 Alloy Deformation Behavior Using Equal Channel Angular Extrusion Process with Different Die Angles

The equal channel angular extrusion (ECAE) is one of the most important methods used for bulk metal forming. In which die angles are the most importent parameter. This paper attempts to determine the effect of different die angles during ECAE process for 6062 aluminum alloy deformation. Numerical simulations are performed for ECAE process on cylindrical billet of 6062 aluminum alloy at a constant frictional coefficient (μ) of 0.08 and punch speed of 15 mm/sec. Die has made with inner corner angles of (φ) =105°, 115°, 125°and 135° by fixing the outer corner angle (ψ) of 6°, punch is designed with a radii (R) of 4.75mm and height of 50mm. From the simulation results, tha data has been obtained in the form of load stroke behavior, and energy consumend during the punch stoke. It is observed that the maximum load and more energy consumption during the process is noted for lower angle.

Characterization of mechanical properties of Al-6063 deformed by ECAE

The production of refined grain materials by equal channel angular extrusion (ECAE) method has been the subject of numerous research programs over the past decades. In this study, the mechanical properties of commercially Al-6063 alloy deformed through ECAE process are investigated. The extrusion is performed up to six passes at a constant speed of 30 mm/min and a temperature of 200 °C. The grain size of the material reduced from 45to 2.8 μm after six passes. The extruded specimens were tested under quasi-static, medium, and high strain rate loadings using various testing machines. The results indicated that the tensile yield stress (YS) and the ultimate tensile strength (UTS) of the extruded specimens increased significantly after five passes of the ECAE process. The major improvement occurred after the first pass. For the subsequent passes, the properties kept improving but at lower rates. It was also shown that the tensile properties of the processed specimens are not influenced by the strain rate.

Enhanced grain refinement of commercial pure copper using the ECAE of Al–Cu–Al tri-layer composite

Equal channel angular extrusion (ECAE) is a promising technique for production of ultrafine grained (UFG) materials of few hundred nanometers size. In this research, the grain refinement of copper strip is accelerated to ultrafine range by sandwiching it between two aluminum strips and then subjecting the three strips to ECAE process simultaneously. After passing the aluminum–copper–aluminum laminated billet through ECAE die up to 8 passes, tensile properties of the copper layer are evaluated. The optical, scanning and transmission electron microscopes, differential scanning calorimeter, and X-ray diffraction were used to characterize the microstructural changes. The results show that the yield stress of the middle layer (Cu) is increased significantly by about eight times after application of four consecutive passes of ECAE and then it is slightly decreased when more ECAE passes are applied. An ultrafine grain within the range of 150 to 200 nm is obtained in the Cu layer.

Effects of ECAE processing temperature on the microstructure, mechanical properties, and corrosion behavior of pure Mg

A two-step equal channel angular extrusion (ECAE) procedure was used to process pure Mg. The effects of ECAE processing temperature on the microstructure, mechanical properties, and corrosion behavior of pure Mg were studied. The results show that the average grain size of pure Mg decreases with decreasing extrusion temperature. After ECAE processing at 473 K, fine and equiaxed grains (~9 μm) are obtained. The sample processed at 473 K exhibits the excellent mechanical properties, whereas the sample processed at 633 K has the lowest corrosion rate. The improved corrosion resistance and mechanical properties of pure Mg by ECAE are ascribed to grain refinement and microstructural modification.

Fabrication and characterization of a biodegradable Mg–2Zn–0.5Ca/1β-TCP composite

A biodegradable magnesium matrix and beta-tricalcium phosphate (β-TCP) particles reinforced composite Mg-2Zn-0.5Ca/1beta-TCP (wt.%) was fabricated for biomedical applications by the novel route of combined high shear solidification (HSS) and equal channel angular extrusion (ECAE). The as-cast composite obtained by HSS showed a fine and equiaxed grain structure with globally uniformly distributed β-TCP particles in aggregates of 2-25 μm in size. The ECAE processing at 300 °C resulted in further microstructural refinement and the improvement of β-TCP particle distribution. During ECAE, the β-TCP aggregates were broken into smaller ones or individual particles, forming a dispersion in the matrix. Such fabricated composite exhibited enhanced hardness and in vitro corrosion resistance. The enhanced hardness was attributed to both the addition of β-TCP particles and grain refinement while the development of a Ca-P rich surface layer from β-TCP during corrosion was responsible for the improvement in corrosion resistance. The composite was characterized in terms of microstructural evolution during fabrication, mechanical properties and electrochemical performance during polarization and immersion tests in a simulated body fluid. Discussions are made on the benefits of both HSS and ECAE and the mechanisms responsible for the enhanced corrosion resistance.

Effect of equal channel angular extrusion on Al-6063 bending fatigue characteristics

The purpose of this investigation was to refine the grains of annealed 6063 aluminum alloy and to improve its yield stress and ultimate strength. This was accomplished via the equal channel angular extrusion (ECAE) process at a temperature of 200°C using route A, with a constant ram speed of 30 mm/min through a die angle of 90° between the die channels for as many as 6 passes. The experiments were conducted on an Avery universal testing machine. The results showed that the grain diameter decreased from 45 μm to 2.8 μm after 6 extrusion passes. The results also indicated that the major improvement in fatigue resistance occurred after the first pass. The subsequent passes improved the fatigue life but at a considerably lower rate. A maximum increase of 1100% in the case of low applied stresses and an approximately 2200% increase in fatigue resistance in the case of high applied stresses were observed after 5 passes. The improvement of fatigue resistance is presumed to be due to (1) a reduction in the size and the number of Si crystals with increasing number of ECAE passes, (2) the aggregation of Cu during the ECAE process, (3) the formation and growth of CuAl2 grains, and (4) grain refinement of the Al-6063 alloy during the ECAE process.

Numerical Investigation of Plastic Deformation in Two-turn Equal Channel Angular Extrusion

There has been a number of investigations in recent years reporting on the structure and properties of materials deformed to super plastic deformation (SPD). During SPD new textures can be formed and abnormal characteristics are displayed, attracting a growing research interest.¶ Equal channel angular extrusion (ECAE) is a method often used to obtain large plastic strains. However, according to experimental results, there is a large tensile stress in the sample during deformation, which may lead in some cases, to cracking in metallic alloys and large curvature in polymeric materials. In order to overcome these drawbacks, the ECAE process can be conducted at high temperatures. But this contributes significantly to a decreased level of plastic deformation induced in the sample. Hence, a tool with multi-pass seems to be a very appropriate solution. In this paper, a new geometry die composed of two elbows has been simulated by finite element method aiming to provide an insight into the mechanisms of deformation and to determine the optimum geometry of the tool. The numerical results show that the length and the section of the second channel play a significant role on the homogeneity of the plastic strain distribution. It has been found that good homogeneity was obtained when the second channel has the same section as that of the entrance and the exit channels and with a length equal to three times of its width.

Mechanical Behavior Enhancement of AM60/Al2O3p Magnesium Metal–Matrix Nanocomposites by ECAE

The effect of equal channel angular extrusion (ECAE) on the mechanical behavior of AM60/Al2O3p magnesium metal–matrix nanocomposites was investigated. ECAE is a useful technique to produce bulk nanostructured materials through severe plastic deformation. The present magnesium metal–matrix composites (Mg MMCs) with 1 wt% nanosized Al2O3 particles for ECAE were fabricated using stir-casting method. The significantly enhanced mechanical behavior of AM60/Al2O3p magnesium metal–matrix nanocomposites at room temperature, for instance, yield strength (YS), ultimate tensile strength (UTS), and ductility, can be obtained after ECAE process. The AM60/Al2O3p MMC after 4 passes of ECAE exhibited greater YS, UTS, and ductility (+135%, +107%, and +245% increase, respectively) than those of as-cast AM60. Experimental results show that the AM60/1wt %Al2O3p MMC after 4 passes of ECAE exhibits the superior mechanical behavior.

Effect of 2θ-Punch Shape on Material Waste during ECAE through a 2θ-Die

This article mainly focusses on the improvement of metal forming die tooling for equal channel angular extrusion (ECAE) processes through nonrectangular 2θ-dies of classical Segal geometry. The technological appropriateness of workpiece deformation through 2θ-dies using inclined oblique 2θ-punches has been evaluated with the introduction of physical simulation techniques. It has been shown experimentally that for the best efficiency, the geometric condition required for the taper angle of the inclined oblique punch is equal to the 2θ angle between the inlet and outlet channels of the angular die. Physical simulation shows that the application of an oblique inclined 2θ-punch provides workpiece dead zone area downsizing and macroscopic rotation reduction during ECAE. The use of numerical finite element modeling simulation also confirms the usefulness of the oblique inclined 2θ-punch for increase of the utilization ratio and decrease of the maximum deformation and unevenness of deformation distribution.

Influence of equal-channel angular extrusion on impact toughness of aluminum and brass at room and low temperatures

Abstract Background Equal-channel angular extrusion is a severe plastic deformation process that can be used for grain refinement to improve material properties of bulk metals. In this paper, the effect of equal-channel angular extrusion on the impact toughness of aluminum 1100 and brass C26000 was investigated. Methods Brass and aluminum materials were extruded in two and four passes using two equal-channel angular extrusion processing routes. Specimens were tested for hardness and Charpy impact toughness. Microstructure and fractography were examined. Results The results showed the hardness remained almost constant after two passes for both brass and aluminum. Impact energy of brass after two passes decreased due to increase in dislocation density whereas for aluminum it remained almost constant after four passes due to the formation of ultrafine grains in addition to deformation/dislocation structures. Impact energies of specimens tested at room temperature and low temperature (−70°C) were almost the same due to their face-centered crystal structure. It was also found that the impact toughness of a specimen with a non-distorted notch surface is higher than that of a specimen with a distorted notch surface. Conclusions It is evident from the present study that the number of passes determines the extent of ultrafine grain structure that is known to increase impact toughness of equal-channel angular extrusion processed materials. All of these observed characteristics can influence material and process selections in practical design applications.

Finite Element Study of Deformation Behaviour of Al-6063 Alloy Developed by Equal Channel Angular Extrusion

The objective of this work is to evaluate the equivalent plastic strain levels induced by equal channel angular extrusion (ECAE) in an annealed Al-6063 alloy after six passes at a temperature of 200°C following route A with a constant ram speed of 30 mm/min through a die angle of 90° between the die channels using the finite element method (FEM). ECAE process is simulated using the DEFORM-3D software through a three-dimensional analysis. Grain refinement is simulated by forcing the element size to zero. It is found that for a very fine mesh the PEEQ converges to 1.046.

Effect of ECAE on Structure and Strength of Porous A6061 Alloy with Aligned Unidirectional Pores

Deformation behavior of porous aluminum alloys with aligned unidirectional pores through equal-channel angular extrusion (ECAE) was investigated. The porous aluminum alloys were fabricated by dipping pure aluminum pipes into semi-solid slurry base metal. The pipes did not detach from the base metal even through the ECAE process. Comparing the sample dimension of pores before and after ECAE process, the amount of decrease in a dimension of pores was 19.4% in this study. The Vickers hardness increased by work hardening. Especially, the hardness value of area where plastic flow arose increased significantly. These results show that we can improve the mechanical properties with maintenance of the porous structure and measure the amount of the sample deformation quantitatively.

Microstructure evolution during semi continuous equal channel angular extrusion process of interstitial- free steel

In order to produce ultrafine grained structures, interstitial-free steel sheets have been processed using a novel severe plastic deformation technique semi continuous equal channel angular extrusion (SC-ECAE) which is based on equal channel angular extrusion (ECAE) in an incremental way. The deformation was carried out at room temperature and individual specimen was repeatedly processed to various passes. An overall grain size which is 0.55 μm was achieved after 10 passes (or an equivalent total strain of 4.8). The present paper reports the evolution of microstructures during deformation, which were examined and characterized using high resolution EBSD in a field emission gun SEM. The mechanisms of grain refinement are discussed.

Microstructure and mechanical properties of an Mg-3Zn- o.5Zr-5HA nanocomposite processed by ECAE

Mg matrix composites reinforced by natural bone constituent hydroxyapatite (HA) particles have shown promising in-vitro corrosion resistance but are inconsistent in both electrochemical and mechanical performances because of severe particle segregations. The present work was carried out to investigate the feasibility of a novel technology that combines high shear solidification and equal channel angular extrusion (ECAE) for fabricating Mg-HA nanocomposites. Experiments showed that the high shear solidification resulted in a fine and uniform grain structure with a globally uniform HA nanoparticles in fine clusters and the ECAE processing of the as-cast composites resulted in further grain refinement and more importantly the breakdown of nanoparticle aggregates, leading to the formation of a dispersion of true nanoparticles in the Mg alloy matrix with improved mechanical properties. This paper describes mainly the microstructural features and mechanical performance of Mg-3Zn-0.5Zr-xHA (x = 1, 3, 5, 10) nanocomposites, in which the HA was in spherical shape with an average diameter of ~20nm

Equal Channel Angular Extrusion of TB2 Alloy under Different Die Designs by Finite Element Method

The influences of different die designs on equal channel angular extrusion (ECAE) process for TB2 alloy (Ti-5Mo-5V-8Cr-3Al) were investigated by finite element method (FEM). Compared with the traditional geometry, the internal radius of newly designed ECAE die is higher than the external radius, and both are tangent to the die walls. Thus, it can be considered as an inverted ECAE. The effects of internal radius and external radius are considered here to analyse the deformation behavior and strain homogeneity of TB2 alloy. It is found that strain homogeneity is improved and punch load is increased obviously when the internal radius is changed from 1 to 3, 5, 7 and 9 mm, respectively. The better strain homogeneity in the TB2 alloy can be achieved with a weak external radius. The optimal plastic strain homogeneity may be acquired with an external radius of 4 mm and an internal radius of 5 mm.

CFD 2D simulation of viscous flow during ECAE through a rectangular die with parallel slants

The objective of this article is the description of advantages of a slanted die geometry, used for equal channel angular extrusion (ECAE) of materials. The prime novelty statement of the present research is an experimental flow pattern, obtained with circular gridlines and a numerical solution of a viscous flow 2D problem for the slanted die, derived with Navier–Stokes equations in curl transfer form. The geometry of the slanted die was chosen for the case of a rectangular die with channel intersection angle 2θ = 90° and with parallel slants in the channel intersection zone, where the slant width is equal to the inlet and outlet channel widths. Computational material flow kinematics, macroscopic rotation patterns, material flow velocity fields, tangential stresses, and punching pressure fields during viscous materials ECAE have been derived with a numerical finite-difference solution of the curl transfer equation for 2D viscous flow of incompressible continuum during ECAE. Theoretical results have been verified with physical simulation experiments by the introduction of initial circular gridlines. Both theoretical and computational results confirm the suitability and technological advantages of dies with parallel slants over the known Segal and Iwahashi dies for ECAE, as slanted convergent dies enable the reduction of the dead zone size and provide the minimization of dangerous macroscopic rotation during ECAE processing of both metal and polymer materials.

Development of Microstructure and Fracture Toughness of AL-6063 Alloy Using Equal Channel Angular Extrusion

Severe plastic deformation (SPD) is one of the processes used to refine the microstructure of materials. Equal Channel Angular Extrusion (ECAE) is the most common method of SPD. In this study, AL-6063grain refinement was performed using the Equal Channel Angular Extrusion method. The material was extruded up to 6 passes at a temperature of 200°C following route A. A suitable die sets equipped with heating elements alongside a thermometer was employed with the intention of extruding the material. Between the two channels, there was an angle of 90°. The results showed that the material grain average diameter decreased from 45μm to 2.8 μm after 6 passes of the ECAE. The Charpy test was used for measuring the fracture energy of various samples. The fracture toughness was the function of this energy. According to this experiment, the fracture toughness rose as the number of the ECAE process elevated. Moreover, the toughness improved for 90% after 6 passes of the ECAE process.

Microhardness Characteristics of Al-6063 Alloy Processed by Equal Channel Angular Extrusion

In this study, annealed AL-6063 alloy was processed by the Equal Channel Angular Extrusion (ECAE) up to 6 passes at a temperature of 200°c following route A with a constant ram speed of 30 mm/min through a die angle of 90° between the die channels. The influence of ECAE processing on the evolution of microhardness in the material was studied using Vickers microhardness testing. The detailed analysis was carried out on the samples of as-received, one, two, three, four, five, and six pass conditions. The grain diameter reduced from 45μm to 2.8 μm after 6 passes of ECAE. The results indicated around 90% increase in Microhardness after 5 passes. Hardness of the inner surface where the billet was under compression was slightly higher than that of the mid-surface.

Finite Element Modelling of Copper by Equal Channel Angular Extrusion

Equal channel angular extrusion (ECAE) is a severe plastic deformation (SPD) method for obtaining bulk nanostructured materials. The ECAE die consists of two equal channels that intersect at an angle, usually between 90o and 135o. . In the present study, the plastic deformation behavior of copper during the ECAE process with 120o die was investigated. To analyze the deformation behavior and the related strain distributions in the specimen, the commercial FE code ABAQUS has been used. The properties of the materials are strongly dependent on the shear plastic deformation behavior during equal channel angular extrusion (ECAE), which is controlled mainly by die geometry, material properties, and the friction between billet and the die. The ECAE process for these conditions was explained using the two different friction conditions of 0.15 and 0.08 to all sliding surfaces. The effective strain by the theoretical equation is in good agreement with the FEM results.

Assessment of the Potential of Three Attritor-milled and Consolidated Nanostructured Materials for Sliding Wear-resistant Applications

This paper deals with the assessment of the potential of nanocrystalline tungsten carbide-cobalt (WCCo), titanium disilicide (TiSi 2 ) and titanium silicide (Ti 5 Si 3 ) for sliding wear-resistant applications. All the materials were milled in a laboratory attritor and the milled powders were consolidated using equal channel angular extrusion (ECAE) process in three cases and chemical consolidation using polycarbosilane (allylhydridopolycarbosilane-AHPCS) in one case. The microhardness of each consolidated sample was measured using a Vickers hardness tester. The crystallite sizes of WCCo, Ti 5 Si 3 and TiSi 2 consolidates after ECAE and Ti5Si3 after attritor milling and prior to chemical consolidation were determined using X-ray diffraction and, the relationship between the crystallite size and microhardness in these cases was examined. The data on microhardness of all the samples was analyzed with reference to current literature to assess the potential of each consolidate for sliding wearresistant applications. The results indicate that attritor-milled Ti 5 Si 3 consolidated using polycarbosilane as the binder appears to have the best potential for sliding wear-resistant applications. The experimental data reported in this paper was obtained by former graduate students under the direction of the author at Lamar University.