Effects of Equal Channel Angular Pressing (ECAP) Process with an Additional Expansion-Extrusion Stage on Microstructure and Mechanical Properties of Mg–9Al–1Zn

محورهای موضوعی : Severe Plastic Defeormation

Mahnoush Rassa ¹ ( Department of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran )
Geonik Azadkoli ² ( Department of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran )
Mohammad Eftekhari ³ ( Department of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran )
Ali Fata ⁴ ( Department of Mechanical Engineering, Faculty of Engineering, University of Hormozgan, Bandar Abbas, Iran )
Ghader Faraji ⁵ ( Department of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran )

تاریخ دریافت : 1400/05/06 تاریخ پذیرش : 1400/06/14 تاریخ انتشار : 1400/08/10

کلید واژه: Severe Plastic Deformation, EECAP, Ultrafine grained metals, AZ91 alloy,

چکیده مقاله :

In this study, equal channel angular pressing (ECAP) process with an additional expansion-extrusion stage named expansion-extrusion equal channel angular pressing (EECAP) process is utilized for producing bulk ultrafine grained (UFG) Mg–9Al–1Zn magnesium alloy. In this process, cyclic expansion-extrusion (CEE) and equal channel angular pressing (ECAP) processes are combined. AZ91 magnesium alloy was used for this experiment. An FEM simulation was performed to calculate the compressive hydrostatical stress. Furthermore, microstructural and mechanical properties were investigated. The experimental findings revealed that the ductility of the sample remains almost constant (0.03% drop) while ultimate tensile strength increased about 30%. The average value of microhardness improved from 48 Hv to 65 Hv (35%) and grain size refined from 144 µm to 3.4 µm. Despite the expansion part of the die, there is no need for back pressure. Another advantage of this new method is maintaining ductility while strengthening.

منابع و مأخذ:

References

1. Xu, S., et al., Dynamic microstructural changes in Mg–9Al–1Zn alloy during hot compression. Scripta Materialia, 2009. 61(3): p. 249-252.


2. Pardis, N., et al., Cyclic expansion-extrusion (CEE): A modified counterpart of cyclic extrusion-compression (CEC). Materials Science and Engineering: A, 2011. 528(25): p. 7537-7540.


3. Celotto, S. and T. Bastow, Study of precipitation in aged binary Mg–Al and ternary Mg–Al–Zn alloys using 27 Al NMR spectroscopy. Acta materialia, 2001. 49(1): p. 41-51.


4. Bursšík, J. and M. Svoboda, A HREM and analytical STEM study of precipitates in an AZ91 magnesium alloy. Microchimica Acta, 2002. 139(1): p. 39-42.


5. Braszczyńska-Malik, K., Spherical shape of γ-Mg 17 Al 12 precipitates in AZ91 magnesium alloy processed by equal-channel angular pressing. Journal of Alloys and Compounds, 2009. 487(1): p. 263-268.


6. Faraji, G., M. Mashhadi, and H. Kim, Microstructure inhomogeneity in ultra-fine grained bulk AZ91 produced by accumulative back extrusion (ABE). Materials Science and Engineering: A, 2011. 528(13-14): p. 4312-4317.


7. Siahsarani, A., et al., Microstructural, Mechanical and Corrosion Properties of AZ91 Magnesium Alloy Processed by a Severe Plastic Deformation Method of Hydrostatic Cyclic Expansion Extrusion. Metals and Materials International, 2020: p. 1-14.


8. Li, Y., et al., Achieving single-pass high-reduction rolling and enhanced mechanical properties of AZ91 alloy by RD-ECAP pre-processing. Materials Science and Engineering: A, 2021. 804: p. 140717.


9. Xu, Q., et al., Microstructure evolution of AZ91 alloy processed by a combination method of equal channel angular pressing and rolling. Journal of Magnesium and Alloys, 2020. 8(1): p. 192-198.


10. Fata, A., et al., Evaluation of Hot Tensile Behavior of Fine-Grained Mg–9Al–1Zn Alloy Tube Processed by Severe Plastic Deformation. Transactions of the Indian Institute of Metals, 2017. 70(5): p. 1369-1376.


11. Cubides, Y., et al., Enhanced mechanical properties and corrosion resistance of a fine-grained Mg-9Al-1Zn alloy: the role of bimodal grain structure and β-Mg17Al12 precipitates. Materialia, 2020. 13: p. 100840.


12. Cubides, Y., et al., Effects of dynamic recrystallization and strain-induced dynamic precipitation on the corrosion behavior of partially recrystallized Mg–9Al–1Zn alloys. Journal of Magnesium and Alloys, 2020. 8(4): p. 1016-1037.


13. Abdolvand, H., et al., Microstructure and mechanical properties of fine-grained thin-walled AZ91 tubes processed by a novel combined SPD process. Bulletin of Materials Science, 2017. 40(7): p. 1471-1479.


14. Ensafi, M., G. Faraji, and H. Abdolvand, Cyclic extrusion compression angular pressing (CECAP) as a novel severe plastic deformation method for producing bulk ultrafine grained metals. Materials Letters, 2017. 197: p. 12-16.


15. Chung, C., et al. Effect of ECAP on microstructure and mechanical properties of cast AZ91 magnesium alloy. in Journal of Physics: Conference Series. 2010: IOP Publishing.


16. Jamali, S., G. Faraji, and K. Abrinia, Evaluation of mechanical and metallurgical properties of AZ91 seamless tubes produced by radial-forward extrusion method. Materials Science and Engineering: A, 2016. 666: p. 176-183.


17. Wang X, Wu M, Ma W, Lu Y, Yuan S. Achieving superplasticity in AZ31 magnesium alloy processed by hot extrusion and rolling. Journal of Materials Engineering and Performance. 2016 Jan;25(1):64-7.


18. Sun Y, Fu L, Fu Z, Shan A, Lavernia EJ. Enhanced thermal stability and ductility in a nanostructured Ni-based alloy. Scripta Materialia. 2017;141: p. 1-5.


19. Figueiredo RB, Langdon TG. Grain refinement and mechanical behavior of a magnesium alloy processed by ECAP. Journal of materials science. 2010;45(17): p. 4827-36.


20. Ebrahimi GR, Maldar AR, Ebrahimi R, Davoodi A. The effect of homogenization on microstructure and hot ductility behaviour of AZ91 magnesium alloy. Kov. Mater. 2010;48: p. 277-84.


21. Siahsarani A, Samadpour F, Mortazavi MH, Faraji G. Microstructural, Mechanical and Corrosion Properties of AZ91 Magnesium Alloy Processed by a Severe Plastic Deformation Method of Hydrostatic Cyclic Expansion Extrusion. Metals and Materials International. 2021;27(8): p. 2933-46.