Numerical Investigation of the Cross-section and Twist Extrusion Die Angle on the Distribution of Plastic Strain and Microstructure of Al7050 Alloy

Document Type: Original Article

Authors

Mechanical Engineering Department, Shahrekord University, Shahrekord, Iran.

10.22084/jrstan.2019.19974.1106

Abstract

Twist extrusion is a novel method for severe plastic deformation of materials. Severe plastic deformation in metals creates small and uniform grain size and therefore increases their mechanical strength. In this study, the effect of die angle in twist extrusion and cross-section of extruded parts on plastic properties and microstructures of Aluminum 7050 alloy was investigated using DEFORM 3D finite element software. Samples were simulated using dies with die angles of 20, 37, and 56 degrees with square, rounded-rectangular, and elliptical cross-sections. The aspect ratios of rectangular and elliptical cross-sections were also changed while keeping the cross-section area constant in order to investigate the effects of dimensions. Plastic strain distribution, gain size distribution, and the force needed for extrusion were extracted under all conditions. The results indicate that increase in die angle significantly reduces grain size and increases the force necessary for extrusion. Removing sharp corners in cross-section also results in more uniform plastic strain distribution and reduction in extrusion force. The elliptical cross-section with dimensions of 9×6mm which had the lowest dimension ratio can reduce grain size from 100ffm to 6ffm in a single pass and requires the lowest extrusion force.

Keywords


[1] Y. Estrin, S.B. Yi, H.G. Brokmeier, Z. Zúberová, S.C. Yoon, H.S. Kim, R.J. Hellmig, Microstructure, texture and mechanical properties of the magnesium alloy AZ31 processed by ECAP, Int. J. Mater. Res., 99(1) (2008) 50-55.
[2] J. Nemati, S. Sulaiman, A. Khalkhali, Improvment in mechanical properties of Titanium deformed by ECAE process, J. Stress Anal., 1(1) (2016) 55-64.
[3] A. Reshetov, R. Kulagin, A. Korshunov, Y. Beygelzimer, The occurrence of ideal plastic state in CP titanium processed by twist extrusion, Adv. Eng. Mater., 20(5) (2018) 1700899.
[4] A. Alavi Nia, S.H. Nourbakhsh, Microstructure and Mechanical Properties of AZ31/SiC and AZ31/CNT Composites Produced by Friction Stir Processing, Trans. Indian Inst. Met., 69(7) (2016)1435-1442.
[5] F. Javadzadeh Kalahroudi, H. Koohdar, H.R. Jafarian, Y. Haung, T.G. Langdonc, M. NiliAhmadabadi, On the microstructure and mechanical properties of an Fe-10Ni-7Mn martensitic steel processed by high-pressure torsion, Mater. Sci. Eng. A, 749 (2019) 27-34.
[6] Y. Beygelzimer, A. Reshetov, S. Synkov, O. Prokof’eva, R. Kulagin, Kinematics of metal flow during twist extrusion investigated with a new experimental method, J. Mater. Process. Technol., 209(7) (2009) 3650-3656.
[7] M. Jahedi, M.H. Paydar, Three-dimensional finite element analysis of torsion extrusion (TE) as an
SPD process, Mater. Sci. Eng. A, 528(29-30) (2011) 8742-8749.
[8] S.A.A. Akbari Mousavi, A.R. Shahab, M. Mastoori, Computational study of Ti-6Al-4V flow behaviors
during the twist extrusion process, Mater. Des., 29(7) (2008) 1316-1329.
[9] J.G. Kim, M. Latypov, N. Pardis, Y.E. Beygelzimer, H.S. Kim, Finite element analysis of the plastic deformation in tandem process of simple shar extrusion and twist extrusion, Mater. Des., 83 (2015) 858-865.
[10] M.I. Latypov, Y. Beygelzimer, H.S. Kim, Comparative analysis of two twist-based SPD processes: Elliptical cross-section spiral equal-channel extrusion vs. Twist Extrusion, Mater. Trans., 54(9) (2013) 1587-1591.
[11] U. Mohammed Iqbal, V. Senthil Kumar, Modeling of twist extrusion process parameters of AA6082-
T6 alloy by response surface approach, Proc. Inst. Mech. Eng. B. J. Eng. Manuf., 228(11) (2014) 1458-1468.
[12] M. Berta, D. Orlov, P.B. Prangnell, Grain refinement response during twist extrusion of an Al-0.13% Mg alloy, Int. J. Mater. Res., 98(3) (2007) 200-204.
[13] S.R. Bahadori, K. Dehghani, S.A.A. Akbari Mousavi, Comparison of microstructure and mechanical properties of pure copper processed by twist extrusion and equal channel angular pressing, Mater. Lett., 152 (2015) 48-52.
[14] Y.E. Beygelzimer, O.V. Prokof’eva, V.N. Varyukhin, Structural changes in metals subjected to direct or twist extrusion: Mathematical simulation, Russ. Metall., 2006(1) (2006) 25-32.
[15] M. Nouri, H.R. Mohammadian Semnani, E. Emadoddin, H.S. Kim, Investigation of direct extrusion channel effects on twist extrusion using experimental and finite element analysis, Measurement, 127 (2018) 115-123.
[16] Y.P. Yi, X. Fu, J.D. Cui, H. Chen, Prediction of grain size for large-sized aluminium alloy 7050 forging during hot forming, J. Cent. South Univ. Technol., 15(1) (2008) 1-5.
[17] V.M. Segal, Severe plastic deformation: simple shear versus pure shear, Mater. Sci. Eng. A, 338(1)
(2002) 331-344.