^{}Department of Mechanical Engineering, Faculty of Eng. , University of Tehran, Tehran, Iran

Abstract

The influence of the sample size (diameter while keeping the length constant) in equal channel angular pressing (ECAP) of pure aluminum is examined using finite element method (FEM) and experiment. Different sized aluminum rods were processed via ECAP and the effect of sample size on the strain homogeneity, process load, and the ratio of the friction to the total force were evaluated. The results showed that there is no distinct trend in variation of the strain homogeneity when the sample diameter is changed though largest diameter sample exhibits the best strain homogeneity. It was apparent that an increase in the sample diameter caused to an increase in the total required load. A decrease in the sample size led to a significant increase in the ratio of the friction to the total force. On the other hand, the friction force is more sensitive than the deformation force to the sample size. More precisely, the friction to total load ratio may be related to the ratio of sample length to the sample diameter (l/d). In a constant sample length, friction to total load ratio amplifies significantly with a decrease in the sample diameter. The present study showed some limitation for the scaling up of the ECAP process for the industrial application especially when increase in the sample length. It may be concluded that ECAP processing is not suitable method for producing of long UFG materials.

1. V. Segal, V. Reznikov, A. Drobyshevskii and V. Kopylov, Plastic working of metals by simple shear, Russ. Met, No. 1, 1981, pp. 99-105. 2. S. L. Semiatin, P. B. Berbon and T. G. Langdon, Deformation heating and its effect on grain size evolution during equal channel angular extrusion, Scripta Materialia, Vol. 44, No. 1, 2001, pp. 135-140. 3. Z. Horita, M. Furukawa, M. Nemoto, A. J. Barnes and T. G. Langdon, Superplastic forming at high strain rates after severe plastic deformation, Acta Materialia, Vol. 48, No. 14, 2000, pp. 3633-3640. 4. S. Komura, P. B. Berbon, M. Furukawa, Z. Horita, M. Nemoto and T. G. Langdon, High strain rate superplasticity in an Al-Mg alloy containing scandium, Scripta Materialia, Vol. 38, No. 12, 1998, pp. 1851-1856. 5. Y. Iwahashi, Z. Horita, M. Nemoto and T. G. Langdon, An investigation of microstructural evolution during equal-channel angular pressing, Acta Materialia, Vol. 45, No. 11, 1997, pp. 4733-4741. 6. Y. Iwahashi, Z. Horita, M. Nemoto and T. G. Langdon, The process of grain refinement in equal-channel angular pressing, Acta Materialia, Vol. 46, No. 9,1998, pp. 3317-3331. 7. C. Xu, Z. Horita and T. G. Langdon, The evolution of homogeneity in processing by high-pressure torsion, Acta Materialia, Vol. 55, No. 1, 2007, pp. 203-212. 8. Y. Saito, H. Utsunomiya, N. Tsuji and T. Sakai, Novel ultra-high straining process for bulk materials—development of the accumulative roll-bonding (ARB) process, Acta Materialia, Vol. 47, No. 2, 1999, pp. 579-583. 9. K. Oh-ishi, A. P. Zhilyaev and T. R. McNelley, Effect of strain path on evolution of deformation bands during ECAP of pure aluminum, Materials Science and Engineering: A, Vol. 410–411, No. 0, 2005, pp. 183-187. 10. P. Zhilyaev, D. L. Swisher, K. Oh-ishi, T. G. Langdon and T. R. McNelley, Microtexture and microstructure evolution during processing of pure aluminum by repetitive ECAP, Materials Science and Engineering: A, Vol. 429, No. 1–2, 2006, pp. 137-148. 11. E. Cerri, P. P. De Marco and P. Leo, FEM and metallurgical analysis of modified 6082 aluminium alloys processed by multipass ECAP: Influence of material properties and different process settings on induced plastic strain, Journal of Materials Processing Technology, Vol. 209, No. 3, 2009, pp. 1550-1564. 12. H. S. Kim, M. H. Seo and S. I. Hong, Plastic deformation analysis of metals during equal channel angular pressing, Journal of Materials Processing Technology, Vol. 113, No. 1–3, 2001, pp. 622-626. 13. S. C. Yoon, P. Quang, S. I. Hong and H. S. Kim, Die design for homogeneous plastic deformation during equal channel angular pressing, Journal of Materials Processing Technology, Vol. 187–188, 2007, pp. 46-50. 14. J.-H. Han, H.-J. Chang, K.-K. Jee and K. H. Oh, Effects of die geometry on variation of the deformation rate in equal channel angular pressing, Metals and Materials International, Vol. 15, No. 3,2009, pp. 439-445. 15. C. Luis Pérez, On the correct selection of the channel die in ECAP processes, Scripta Materialia, Vol. 50, No. 3, 2004, pp. 387-393. 16. H. S. Kim, M. H. Seo and S. I. Hong, Finite element analysis of equal channel angular pressing of strain rate sensitive metals, Journal of Materials Processing Technology, Vol. 130–131, 2002, pp. 497-503. 17. G. Deng, C. Lu, L. Su, X. Liu and A. Tieu, Modeling texture evolution during ECAP of copper single crystal by crystal plasticity FEM, Materials Science and Engineering: A, Vol. 534, 2012, pp. 68-74. 18. V. Nagasekhar and H. S. Kim, Analysis of T-shaped equal channel angular pressing using the finite element method, Metals and Materials International, Vol. 14, No. 5, 2008, pp. 565-568. 19. S. Yoon, A. Nagasekhar and H. Kim, Finite element analysis of the bending behavior of a workpiece in equal channel angular pressing, Metals and Materials International, Vol. 15, No. 2, 2009, pp. 215-219. 20. H. S. Kim, M. H. Seo and S. I. Hong, On the die corner gap formation in equal channel angular pressing, Materials Science and Engineering: A, Vol. 291, No. 1–2, 2000, pp. 86-90. 21. T. Suo, Y. Li, Y. Guo and Y. Liu, The simulation of deformation distribution during ECAP using 3D finite element method, Materials Science and Engineering: A, Vol. 432, No. 1, 2006, pp. 269-274. 22. V. P. Basavaraj, U. Chakkingal, T. P. Kumar, Study of inner corner influence in equal Channel Angular Pressing using 3D finite element simulation, Transactions of the Indian Institute of Metals, Vol. 61, 2008, pp. 125-129. 23. S. Xu, G. Zhao, Y. Luan and Y. Guan, Numerical studies on processing routes and deformation mechanism of multi-pass equal channel angular pressing processes, Journal of Materials Processing Technology, Vol. 176, No. 1–3, 2006, pp. 251-259. 24. H. Jiang, Z. Fan and C. Xie, 3D finite element simulation of deformation behavior of CP-Ti and working load during multi-pass equal channel angular extrusion, Materials Science and Engineering: A, Vol. 485, No. 1, 2008, pp. 409-414. 25. Z. Horita, T. Fujinami and T. G. Langdon, The potential for scaling ECAP: effect of sample size on grain refinement and mechanical properties, Materials Science and Engineering: A, Vol. 318, No. 1–2, 2001, pp. 34-41. 26. G. Y. Deng, C. Lu, L. H. Su, A. K. Tieu, H. L. Yu and X. H. Liu, Investigation of sample size effect on the deformation heterogeneity and texture development during equal channel angular pressing, Computational Materials Science, Vol. 74, 2013, pp. 75-85. 27. P. K. Chaudhury, B. Cherukuri and R. Srinivasan, Scaling up of equal-channel angular pressing and its effect on mechanical properties, microstructure, and hot workability of AA 6061, Materials Science and Engineering: A, Vol. 410, 2005, pp. 316-318. 28. G. Faraji, M. M. Mashhadi, S.-H. Joo and H. S. Kim, The role of friction in tubular channel angular pressing, Rev. Adv. Mater. Sci, Vol. 31, 2012, pp. 12-18. 29. V. Nagasekhar, S. C. Yoon, Y. Tick-Hon and H. S. Kim, An experimental verification of the finite element modelling of equal channel angular pressing, Computational Materials Science, Vol. 46, No. 2, 2009, pp. 347-351. 30. N. E. Mahallawy, F. A. Shehata, M. A. E. Hameed, M. I. A. E. Aal and H. S. Kim, 3D FEM simulations for the homogeneity of plastic deformation in Al–Cu alloys during ECAP, Materials Science and Engineering: A, Vol. 527, No. 6, 2010, pp. 1404-1410. 31. P. B. Prangnell, C. Harris and S. M. Roberts, Finite element modelling of equal channel angular extrusion, Scripta Materialia, Vol. 37, No. 7, 1997, pp. 983-989. 32. S. Li, I. J. Beyerlein, C. T. Necker, D. J. Alexander and M. Bourke, Heterogeneity of deformation texture in equal channel angular extrusion of copper, Acta Materialia, Vol. 52, No. 16, 2004, pp. 4859-4875. 33. G. Faraji, M. M. Mashhadi and H.S. Kim, Deformation Behavior in Tubular Channel Angular Pressing (TCAP) Using Triangular and Semicircular Channels, Materials Transactions, Vol. 53, No. 01, 2012, pp. 8-12. 34. G. Faraji, M. Mashhadi, A. Dizadji and M. Hamdi, A numerical and experimental study on tubular channel angular pressing (TCAP) process, Journal of mechanical science and technology, Vol. 26, No. 11, 2012, pp. 3463-3468. 35. G. J. Raab, R. Z. Valiev, T. C. Lowe and Y. T. Zhu, Continuous processing of ultrafine grained Al by ECAP–Conform, Materials Science and Engineering: A, Vol. 382, No. 1–2, 2004, pp. 30-34. 36. N. D. Stepanov, A. V. Kuznetsov, G. A. Salishchev, G. I. Raab, R. Z. Valiev, Effect of coldro and ling on microstructure and mechanical properties of copper subjected to ECAP withvarious numbers of passes, Materials Science and Engineering: A, Vol. 554, 2012, pp. 105- 115.