Numerical and Experimental Investigation on Hot Backward Extrusion Process of Mg-Gd-Y-Zn-Zr Magnesium Alloy

Abstract:

The hot backward extrusion process of the Mg-Gd-Y-Zn-Zr magnesium alloy was investigated by both numerical simulation and experiments. An axisymmetric 2D rigid-plastic finite element model (FEM) was established to simulate the material flow during the extrusion process. The shapes of the dies were optimized in order to avoid severe stress concentration and obtain uniform deformation of the workpiece. After hot extrusion, the microstructures of the alloys were obviously refined, and the secondary phases which included many long-period stacking order (LPSO) phases precipitated in the matrix. The optimal comprehensive mechanical properties of the alloy have been obtained after extrusion and ageing at 200°C for 48h with the ultimate tensile strength of 434MPa, tensile yield strength of 375MPa and elongation of 4.5%, respectively. The good mechanical properties were mainly attributed to the fine microstructures and numerous precipitates in the matrix.

• Periodical: Materials Science Forum (Volume 788)
• Pages: 127-133
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.788.127
• Online since: April 2014
• Authors: Zhi Wen Shao*, Xiu Rong Zhu, Jun Wang, Rong Wang, Yong Dong Xu, Bao Rong Zhao, Guo Ping Ling
• Keywords: Hot Extrusion, Mechanical Property, Microstructure, Numerical Simulation

References

[1] Wang J, Meng J, Zhang DP et al. Effect of Y for enhanced age hardening response and mechanical properties of Mg-Gd-Y-Zr alloys. Mater Sci Eng A2007;456:78-84.

DOI: 10.1016/j.msea.2006.11.096

[2] He SM, Zeng XQ, Peng LM et al. Microstructure and strengthening mechanism of high strength Mg–10Gd–2Y–0.5Zr alloy. J Alloys Compd 2007; 427:316-323.

DOI: 10.1016/j.jallcom.2006.03.015

[3] Lin L, Chen L, Liu Z. Tensile strength improvement of an Mg–12Gd–3Y (wt%) alloy processed by hot extrusion and free forging. J Mater Sci 2008;43:4493-4502.

DOI: 10.1007/s10853-008-2650-x

[4] Yamada K, Okubo Y, Shiono M et al. Alloy development of high toughness Mg-Gd-Y-Zn-Zr alloys. Materials Transactions. 2006;47 1066-1070.

DOI: 10.2320/matertrans.47.1066

[5] Liu XB, Chen RS, Han EH. Effects of ageing treatment on microstructures and properties of Mg-Gd-Y-Zr alloys with and without Zn addition. J Alloys Compd 2008; 465:232-238.

DOI: 10.1016/j.jallcom.2007.10.068

[6] Fumin L, Aibin M, Jinghua J et al. Review on long-period stacking-ordered structures in Mg-Zn-RE alloys. RARE METALS 2012;31:303-310.

DOI: 10.1007/s12598-012-0510-y

[7] Al-Samman T, Gottstein G. Dynamic recrystallization during high temperature deformation of magnesium. Materials Science and Engineering A 2008;490:411-420.

DOI: 10.1016/j.msea.2008.02.004

[8] Selvan SA, Ramanathan S, Hot workability of as-cast and extruded ZE41A magnesium alloy using processing maps. Transaction of Nonferrous Metals Society of China 2011;21:257-264.

DOI: 10.1016/s1003-6326(11)60707-3

[9] Li HZ, H.J. Wang, Z.Li et al. Flow behavior and processing map of as-cast Mg-10Gd-4.8Y-2Zn-0.6Zr alloy. Materials Science and Engineering A 2010;528:154-160.

DOI: 10.1016/j.msea.2010.08.090

[10] Shao Z, Zhu X, Wang R et al. Hot deformation and processing map of as-homogenized Mg–9Gd–3Y–2Zn–0.5Zr alloy. Materials and Design. 2013;51 826-832.

DOI: 10.1016/j.matdes.2013.04.095

[11] Shan D, Xu W, Han X et al. Study on isothermal precision forging process of rare earth intensifying magnesium alloy. Materials Science and Engineering B. 2011;177:1698-1702.

DOI: 10.1016/j.mseb.2011.10.006

[12] Zhou HT, Liu CM, Chen MA. Constitutive model development and hot extrusion simulation for AZ61 magnesium alloy. Materials Science and Technology. 2006;22:597-603.

DOI: 10.1179/174328406x84030

[13] Xu C, Zheng MY, Xu SW et al. Microstructure and mechanical properties of Mg-Gd-Y-Zn-Zr alloy sheets processed by combined processes of extrusion, hot rolling and ageing. Materials Science & Engineering A. 2013;559:844-851.

DOI: 10.1016/j.msea.2012.09.032

[14] Honma T, Kunito N, Kamado S et al. Fabrication of extraordinary high-strength magnesium alloy by hot extrusion. Scripta Mater 2009;61:644-647.

DOI: 10.1016/j.scriptamat.2009.06.003

[15] Yang Z, Guo YC, Li JP et al. Plastic deformation and dynamic recrystallization behaviors of Mg–5Gd–4Y–0.5Zn–0.5Zr alloy. Mater Sci Eng A 2008;485:487–491.

DOI: 10.1016/j.msea.2007.08.069

[16] Zhang S, Yuan GY, Lu C et al. The relationship between (Mg,Zn)3RE phase and 14H-LPSO phase in Mg-Gd-Y-Zn-Zr alloys solidified at different cooling rates. J Alloys Compd 2011;509:3515-3521.

DOI: 10.1016/j.jallcom.2010.12.136

[17] Li DJ, Zeng QX, Dong J et al. Microstructure evolution of Mg–10Gd–3Y–1.2Zn–0.4Zr alloy during heat-treatment at 773K. J Alloys Compd 2009;468:164-169.

DOI: 10.1016/j.jallcom.2008.01.078