Papers by Keyword: Equal Channel Angular Extrusion (ECAE)

Abstract: 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.

Abstract: 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.

Abstract: In the present study, the impact strength of annealed Al-6063 alloy developed by 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 was investigated. The impact strength of extruded specimens is evaluated for different passes at a strain rate of 1800 s^-1 using Split-Hopkinson pressure bar techniques. The results indicate that the major strength improvement occurs in the 5^th and 6^th passes while in primary passes, the strength improved but at a considerably lower rate. A total increasing in ultimate strength (UTS) and yield strength (YS) are 127% and 65% respectively and observed for the extruded material after 6 passes. Optical microscopic examinations show a grain refinement from 45 μm to 2.8 μm.

Abstract: Grain refinement taking place in a commercial 7055 aluminum alloy under equal channel angular pressing (ECAP) was examined in the temperature interval 250375°C. It was shown that the formation of recrystallized grains occurs through continuous dynamic recrystallization (CDRX). At 250°C, a low rate of dynamic recovery and high volume fraction of second phase particles provide the rapid formation of stable three-dimensional arrays of low-angle boundaries and their gradual transformation into high-angle boundaries. Increasing temperature leads an increase in the average crystallite size produced by ECAP from 0.7 μm at 250°C to 1.3 μm at 375°C. The effect of temperature on CDRX kinetic is discussed.

Abstract: The deformed microstructure and recrystallization behavior of copper samples processed using equal channel angular extrusion (ECAE) have been investigated. The heavily deformed microstructure was found to be non-uniform through the sample thickness and to vary in a manner consistent with the non-uniform distribution of strain imposed by processing. The through-thickness heterogeneity of the deformed microstructure resulted in a different extent of recrystallization in different layers during annealing. Recrystallized grains were also observed in samples that were not annealed, but stored at room temperature, which indicates that the deformed microstructure of ECAE-processed pure copper is unstable even at room temperature. In each sample, recrystallization was found to initiate in regions containing predominantly large misorientations.

Abstract: Recent studies have shown that Severe Plastic Deformation (SPD) processes improve the mechanical properties of the parts processed, through a reduction in the grain size. Equal Channel Angular Extrusion (ECAE) is one of the best -known SPD processes. A study was made of the force and the strain after two ECAE passages, as well as of the damage imparted to AA-6082, by means of experiments and Finite Element Simulations (FEM). The aim of this present research is to make a comparative study between experimental results and those obtained by FEM in order to verify the feasibility of these FEM simulations. In addition to this, it is intended to analyze the homogeneity obtained in the strain values after two ECAE passages made through route C.

Abstract: It is shown that implementation of high strains through equal-channel angular pressing (ECAP) and/or rolling into alloys belonging to Al-Mg-Sc-Zr system allows achieving high strength and satisfactory ductility. It was shown that strain hardening gives a main contribution to overall strength increment attributed to intense plastic straining; the role of grain size hardening is minor. However, extensive grain refinement is a necessary condition for retaining sufficient ductility in full-hardened condition for these materials.

Abstract: The finite element analysis was applied to evaluate the respective influences of die geometry and process conditions on plastic strain distribution for β-titanium (Ti-13V11Cr3Al) during the equal channel angular extrusion. It was found that optimum ECAE die geometry is strongly material dependent. Optimal strain homogeneity in the Ti-13V11Cr3Al alloy may be achieved at r (inner radius) =5mm, R (outer radius) =3mm. The equivalent plastic strain increases with increasing friction coefficient. And the better homogeneity of the equivalent plastic strain distribution can be achieved when m=0.1. The faster is the ram speed, the lower is the homogeneity of the equivalent plastic strain distribution. The back-pressure can increase the strain level across the workpiece and prevent the problem of surface cracking induced by tensile stresses. The distribution of the plastic strain is not temperature sensitive between 400°C and 600°C.

Abstract: Grain size refinement by using equal channel angular Extrusion (ECAE) is an effective way to improve workability and strength of the magnesium alloys. Round workpieces of ECAE processes for AZ31 magnesium alloy are investigated by using numerical simulations and experimental studies in this paper. The processing of ECAE is simulated in order to study the influence of the processing on the deformation behavior of the workpiece and extruding load. The variation trends of the effective strain distributions in the workpiece are changed little for different cross-section. Punch load for extrusion is the major factor to be considered while designing a sound ECAE die. The deformation mechanism of ECAE for grain refinement is obtained. In addition, the experimental finally workpieces shapes and extruding load results are also consistent with FE analysis results.

Abstract: Lotus-type porous aluminum with cylindrical pores oriented in one direction was deformed by Equal Channel Angular Extrusion (ECAE) through a 150° die with sequential 180° rotations, and the pore morphology and Vickers hardness after the extrusion were investigated. The Vickers hardness increases with increasing number of passes in the extrusions both parallel and perpendicular to the pore direction, accompanied by the decrease of porosity. The densification occurs more easily in the perpendicular extrusions than in the parallel extrusions, and the large deformation by the densification gives rise to the large increase in the Vickers hardness for the perpendicular extrusions.