The Effect of ECAP Die Helix Angle on the Microstructure Homogeneity of the Processed Samples by FEM Method
محورهای موضوعی : Metal FormingAmir Neshastegir Kashi 1 , Farshid Ahmadi 2
1 - Department of Mechanical Engineering, University of Kashan, Kashan, 8731753153, Iran
2 - Department of Mechanical Engineering, University of Kashan, Kashan, 8731753153, Iran
کلید واژه: ECAP, Taguchi approach, Homogeneity, Helix angle, Frictional Coefficient, Die Angle,
چکیده مقاله :
Equal channel angular pressing is one of the most popular processes for the fabrication of ultrafine-grained (UFG) materials. Homogeneous strain distribution is one of the main expected outputs in this process. Recently, a new modification has been applied on the ECAP die in which the workpiece undergoes twisting in the exit channel which is defined as the helix angle of the die. In this paper, the effect of the helix angle in the exit channel along with other effective parameters, including friction coefficient and die channel angle was investigated by the FEM method. At first, a FEM model was developed based on available experimental data. Having verified the FEM model, Taguchi's design of the experimental approach was employed in which the helix angle and friction coefficient had four levels and the die channel angle had two levels. Evaluating the obtained results by the ANOVA method showed that the p-value of the helix angle was 0.01 i.e., the helix angle was an effective parameter on strain distribution and maximum imposed strain. The results also showed that the homogeneity of strain distribution decreases with increasing the friction coefficient and the helix angle and increases with increasing the die channel angle. Also, increasing the helix angle led to an increase in the maximum imposed strain.
[1] Segal, V. 1995. Materials processing by simple shear. Materials Science and Engineering: A. 197(2): 157-164.
[2] Segal, V. 1999. Equal channel angular extrusion: From macromechanics to structure formation. Materials Science and Engineering: A. 271(1-2): 322-333.
[3] Nemati, J., Majzoobi, G., Sulaiman, S., Baharudin, B. and Hanim, M.A. 2014. Finite element and metallurgical study of properties of deformed pure copper by ecae at various strain rates. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science. 228(9): 1461-1473.
[4] Ahmadi, F. and Farzin, M. 2014. Finite element analysis of ultrasonic-assisted equal channel angular pressing. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science. 228(11): 1859-1868.
[5] Chung, S., Somekawa, H., Kinoshita, T., Kim, W. and Higashi, K. 2004. The non-uniform behavior during ecae process by 3-d fvm simulation. Scripta Materialia. 50(7): 1079-1083.
[6] Kim, W. and Namkung, J. 2005. Computational analysis of effect of route on strain uniformity in equal channel angular extrusion. Materials Science and Engineering: A. 412(1-2): 287-297.
[7] El Mahallawy, N., Shehata, F.A., El Hameed, M.A., El Aal, M.I.A. and Kim, H.S. 2010. 3d fem simulations for the homogeneity of plastic deformation in al–cu alloys during ecap. Materials Science and Engineering: A. 527(6): 1404-1410.
[8] Mogucheva, A., Babich, E., Ovsyannikov, B. and Kaibyshev, R. 2013. Microstructural evolution in a 5024 aluminum alloy processed by ecap with and without back pressure. Materials Science and Engineering: A. 560: 178-192.
[9] Lu, S., Liu, H., Yu, L., Jiang, Y. and Su, J. 2011. 3d fem simulations for the homogeneity of plastic deformation in aluminum alloy hs6061-t6 during ecap. Procedia Engineering. 12: 35-40.
[10] Djavanroodi, F., Daneshtalab, M. and Ebrahimi, M. 2012. A novel technique to increase strain distribution homogeneity for ecaped materials. Materials Science and Engineering: A. 535: 115-121.
[11] Zhang, X. and Cheng, Y. 2017. Influence of inner fillet radius on effective strain homogeneity in equal channel angular pressing. The International Journal of Advanced Manufacturing Technology. 92(9-12): 4001-4008.
[12] Ahmadi, F. and Farzin, M. 2014. Investigation of a new route for equal channel angular pressing process using three-dimensional finite element method. Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture. 228(7): 765-774.
[13] Nejadseyfi, O., Shokuhfar, A., Azimi, A. and Shamsborhan, M. 2015. Improving homogeneity of ultrafine-grained/nanostructured materials produced by ecap using a bevel-edge punch. Journal of materials science. 50(3): 1513-1522.
[14] Ahmadi, F., Farzin, M., Meratian, M., Loeian, S. and Forouzan, M. 2015. Improvement of ecap process by imposing ultrasonic vibrations. The International Journal of Advanced Manufacturing Technology. 79(1-4): 503-512.
[15] Ghazani, M.S., Binesh, B. and Fardi-Ilkhchy, A. 2019. Effect of strain rate sensitivity and strain hardening exponent of materials on plastic strain distribution and damage accumulation during equal channel angular pressing. Iranian Journal of Science and Technology, Transactions of Mechanical Engineering. 43(1): 831-844.
[16] Fereshteh-Saniee, F., Asgari, M., Barati, M. and Pezeshki, S.M. 2014. Effects of die geometry on non-equal channel lateral extrusion (necle) of az80 magnesium alloy. Transactions of Nonferrous Metals Society of China. 24(10): 3274-3284.
[17] Chrominski, W., Olejnik, L., Rosochowski, A. and Lewandowska, M. 2015. Grain refinement in technically pure aluminium plates using incremental ecap processing. Materials Science and Engineering: A. 636: 172-180.
[18] Kocich, R., Kunčická, L., Král, P. and Macháčková, A. 2016. Sub-structure and mechanical properties of twist channel angular pressed aluminium. Materials Characterization. 119: 75-83.
[19] Snopińśki, P., Tański, T., Matus, K. and Rusz, S. 2019. Microstructure, grain refinement and hardness of al–3% mg aluminium alloy processed by ecap with helical die. Archives of Civil and Mechanical Engineering. 19(2): 287-296.
[20] Li, S., Bourke, M., Beyerlein, I., Alexander, D. and Clausen, B. 2004. Finite element analysis of the plastic deformation zone and working load in equal channel angular extrusion. Materials Science and Engineering: A. 382(1-2): 217-236.
