Microstructural characteristics and deformation of magnesium alloy AZ31 produced by continuous variable cross-section direct extrusion

doi:10.1016/j.jmst.2017.01.003

Abstract

Abstract:

Magnesium (Mg) alloy AZ31 was produced by continuous variable cross-section direct extrusion (CVCDE) to study its deformation behavior. Metallographic microscopy (OM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were used to observe the variations in microstructure and fracture morphology of Mg alloy AZ31 as a function of processing methods. The results reveal that grains of Mg alloy AZ31 were refined and their microstructure was homogenized by CVCDE. The recrystallization in Mg alloy AZ31 produced by CVCDE with 2 interim dies was more complete than that produced by conventional extrusion (CE) and CVCDE with 1 interim die, and the grains were finer and more uniform. Plasticity of the AZ31 alloy was improved. Fracture mode was evolved from a combination of ductility and brittleness to a sole ductile form. In summary, a CVCDE mold structure with 2 interim dies can improve microstructure, plasticity, and toughness of Mg alloy AZ31.

Key words: Continuous variable cross-section direct extrusion (CVCDE), Magnesium alloys, Microstructural characteristics, Plastic deformation

Jiang Hongwei, Li Feng, Zeng Xiang. Microstructural characteristics and deformation of magnesium alloy AZ31 produced by continuous variable cross-section direct extrusion[J]. J. Mater. Sci. Technol., 2017, 33(6): 573-579.

Figures/Tables 8

Fig 1. Schematic illustration of CVCDE: (a) the second interim die; (b) the first interim die; and (c) CE die.

Table 1 Chemical composition of Mg alloy AZ31.

Al	Zn	Mn	Fe	Si	Cu	Ni	Mg
3.20	0.86	0.36	0.0018	0.021	0.0022	0.00056	Bal.

Fig. 2. Metallographic images of ND: (a) billet; (b) CE; (c) CVCDE with 1 interim die; (d) CVCDE with 2 interims dies.

Fig. 3. (a) Photograph of the products of CE, CVCDE with 1 interim die and 2 interim dies; and (b) mechanical properties of CE, CVCDE with 1 interim die and 2 interim dies.

Fig. 4. TEM micrographs of CE: (a) grain morphology; and (b) dislocation distribution.

Fig. 5. TEM micrographs of CVCDE with 1 interim die: (a) grain morphology; (b) dislocation structures within coarse grain interior; (c) subgrain; and (d) absorption of dislocations into subgrain boundaries.

Fig. 6. TEM micrographs of CVCDE with 2 interim dies: (a) grain morphology, (b) dislocation structure within coarse grain interior, (c) tangle dislocation, and (d) high grain boundary and subgrain boundary.

Fig. 7. SEM micrographs of fracture morphology of: (a) original billet, (b) CE, (c) CVCDE with 1 interim die, and (d) CVCDE with 2 interim dies.

References

[1]	J.R. Dong, D.F. Zhang, J. Sun, Q.W. Dai, F.S.Pan J. Mater. Sci. Technol., 31(2015), pp. 935-940
[2]	M. Kaseem, B.K. Chung, H.W. Yang, K. Hamad, Y.G.Ko J. Mater. Sci. Technol., 31(2015), pp. 498-503
[3]	D. Sarker, J. Friedman, D.L.Chen J. Mater. Sci. Technol., 31(2015), pp. 264-268
[4]	G. Faraji, P. Yavari, S. Aghdamifar, M.M.Mashhadi J. Mater. Sci. Technol., 30(2014), pp. 134-138
[5]	J.B. Lin, X.Y. Wang, W.J. Ren, X.X. Yang, Q.D.Wang J. Mater. Sci. Technol., 32(2016), pp. 783-789
[6]	S. Seipp, M.F.-X.Wagner, K. Hockauf, I.Schneider, L.W. Meyer, M. Hockauf Int. J. Plast., 35(2012), pp. 155-166
[7]	R.B. Figueiredo, T.G.Langdon Mater. Sci. Eng. A, 528(2011), pp. 4500-4506
[8]	Q.D. Wang, Y.J. Chen, M.P. Liu, J.B. Lin, H.J.Roven Mater. Sci. Eng. A, 527(2010), pp. 2265-2273
[9]	Q. Chen, B.G. Yuan, J. Lin, X.S. Xia, Z.D. Zhao, D.Y.Shu J. Alloy. Compd., 584(2014), pp. 63-75
[10]	N. Stanford, D. Atwell, A. Beer, C. Davies, M.R.Barnett Scr. Mater., 59(2008), pp. 772-775
[11]	T. Al-Samman, X. LiMater.Sci. Eng. A, 528(2011), pp. 3809-3822
[12]	Z. Wang, J.H. Perepezko, D. Larson, D. ReinhardJ.Alloy. Compd., 643(2015), pp. S246-S249
[13]	Q. Chen, Z.D. Zhao, G. Chen, B. WangJ.Alloy. Compd., 632(2015), pp. 190-200
[14]	Z. ZhangMater.Sci. Eng. A, 577(2013), pp. 125-137
[15]	F. Li, X. Zeng, N. BianMater.Lett., 135(2014), pp. 79-82
[16]	A. Galiyev, R. Kysaibhev, G. Gottstein Acta Mater., 49(2001), pp. 1199-1207
[17]	H. Zhang, Q.Q. Yan, L.X.Li Mater. Sci. Eng. A, 486(2008), pp. 295-299
[18]	P.S. Roodposhti, A. Sarkar, K.L.Murty Mater. Sci. Eng. A, 626(2015), pp. 195-202
[19]	F. Li, W. Shi, N. Bian, H.B.Wu Acta Metall. Sin.(Engl. Lett.), 28(2015), pp. 649-655
[20]	J. Deng, Y.C. Lin, S. Li, J. Chen, Y. DingMater.Des., 49(2013), pp. 209-219
[21]	Y.B. He, Q.L. Pan, Y.J. Qin, X.Y. Liu, W.B. Li, Y.L. Chiu, J. John, J. ChenJ.Alloy Compd., 492(2010), pp. 605-610
[22]	J.C. Tan, M.J.Tan Mater. Sci. Eng. A, 339(2003), pp. 124-132