Microstructural Evolution and Service Performance of Cold-drawn Pure Aluminum Conductor Wires

doi:10.1016/j.jmst.2016.11.018

Abstract

Abstract:

Microstructures and service performance (mechanical and electrical properties) of the commercially pure Al conductor wires subjected to different cold drawing strains were investigated. The results show that the microstructures of the cold-drawn Al wires along the radial direction were inhomogeneous, i.e. the texture in the center region was strong <111> and weak <001> components, while that in the surface region shifted from the initial cubic texture to a <112> component and finally developed into a strong <111> component. The volume fraction of the high angle grain boundaries in the surface region was higher than that in the center region. The cold-drawing process greatly enhanced the yield strength of the pure Al wires while retained the acceptable electrical resistivity. The strengthening mechanism and the variation of electrical conductivity of the cold-drawn Al wires are discussed through correlating with microstructure evolution.

Key words: Cold drawing, Aluminum, Microstructure, Strength, Conductivity

Luo X.M., Song Z.M., Li M.L., Wang Q., Zhang G.P.. Microstructural Evolution and Service Performance of Cold-drawn Pure Aluminum Conductor Wires[J]. J. Mater. Sci. Technol., 2017, 33(9): 1039-1043.

Figures/Tables 9

Table 1 Chemical compositions of commercial pure aluminum (wt%)

Al	Si	Fe	Cu	Mn	Mg	Cr	Ni	Zn
99.6	0.11	0.25	0.01	—	—	—	—	0.06

Fig. 1. Schematic illustration of the cold drawing process. The drawing pass and the corresponding deformation strain are indicated in the image.

Table 2 Diameter (D) and the corresponding area reduction (AR) and equivalent strain (ε) of cold-drawn Al wires in each pass

Pass	0	1	2	3	4	5	6	7	8	9
D (mm)	9.50	8.10	6.98	6.58	5.80	5.28	4.56	3.97	3.42	2.99
AR (%)	0	26.7	46.1	52.1	62.7	69.1	76.9	82.5	87.4	90.1
ε	0	0.31	0.62	0.74	0.99	1.17	1.47	1.74	2.04	2.31

Fig. 2. EBSD GB maps of the center and the surface regions of the Al wires drawn to various strains of (a) and (b) ε?=?0.62, (c) and (d) ε?=?0.99, (e) and (f) ε?=?1.47, (g) and (h) ε?=?2.04. The characterized plane is that parallel to the drawing direction (DD), as shown in the schematic drawing on the bottom. In the boundary maps, the thicker black lines represent the GB with misorientationbeyond 15°, while the gray lines represent the boundaries with misorientation between 2° and 15°.

Fig. 3. Fraction of HAGBs in the center and the surface regions of the Al wires drawn to various strains.

Fig. 4. Inverse pole figures of the drawing direction (DD) in the center and the surface regions of the Al wires drawn to various strains of (a) and (b) ε?=?0.62, (c) and (d) ε?=?0.99, (e) and (f) ε?=?1.47, (g) and (h) ε?=?2.04. The characterized plane is that parallel to the drawing direction, as shown in the schematic drawing on the bottom.

Fig. 5. Distribution of Schmid factor of the Al wires drawn to various drawing strains.

Fig. 6. Yield strength and uniform elongation of the Al wires subjected to different drawing strains.

Fig. 7. Electric conductivity of the cold-drawn Al wires as a function of equivalent drawing strain.

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