1. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China 2. School of Materials Science and Engineering, University of Science and Technology of China, Shenyang 110016, China
Cite this article:
Dechun REN, Huhu SU, Huibo ZHANG, Jian WANG, Wei JIN, Rui YANG. Effect of Cold Rotary-Swaging Deformation on Microstructure and Tensile Properties of TB9 Titanium Alloy. Acta Metall Sin, 2019, 55(4): 480-488.
TB9 titanium alloy has been widely used for aerospace due to it's superior low stiffness, corrosion resistance and workability. It has been reported that cold deformation can improve the comprehensive mechanical properties of titanium alloys. At the same time, the cold rotary-swaging deformation facilitates the production of small batches and the acquisition of special shape and size bars. However, current studies on the microstructure and properties of cold rotary-swaged titanium alloys are not systematic. So, the effects of cold deformation rate on the microstructure, texture evolution and mechanical property of TB9 alloy during cold rotary-swaging were investigated using OM, EBSD, XRD, TEM and tensile test. The results showed that the grain size of TB9 titanium was refined with the increase in diameter reduction. Meanwhile, with the deformation increases, the grains rotation along the swaging axis occurs, forming a preferred orientation, the textures change from initial {001}<110> and {001}<100> to α-fiber and γ-fiber {001}<110>, {112}<110> and {111}<110>. All of grains refinement, texture components and substructures contributed to the enhancement of strength after cold rotary-swaging. And the ductile kept on a high level after 70% cold working, which means the TB9 titanium has a great cold deformation ability.
Fig.1 OM image (a), TEM image and SAED pattern (b) and EBSD analyses (c~e) of the solution microstructure of TB9 titanium alloy (The red lines and green lines in Fig.1e indicate high-angle grain boundaries (HAGBs) with misorientation angles of over 15o and low-angle grain boundaries (LAGBs) with misorientation angles of 2o~15o, respectively. RD—rolling direction)
Fig.2
Fig.3 OM images (a~c) and EBSD analyses (d~f) of TB9 titanium alloy under cold rotary-swaging rates of 15% (a, d), 35% (b, e) and 70% (c, f) (RS—rotary-swaging direction)
Fig.4
Fig.5 TEM images of TB9 titanium alloy under cold rotary-swaging rates of 15% (a), 35% (b), 70% (c), and SAED pattern of bright band under 70% cold rotary-swaging rate (d) (Inset in Fig.5c show the SAED pattern of dark band)
Fig.6 EBSD contrast band map showing sheer bands of TB9 titanium alloy under cold rotary-swaging rate of 70% (a) and distribution of misorientation along the arrow in Fig.6a (b)
Fig.7 Pole figures of TB9 titanium alloy under cold rotary-swaging rates of 15% (a), 35% (b) and 70% (c)
Fig.8 Sections (φ2=45o) of orientation distribution functions (ODFs) of solution treated TB9 titanium alloy (a) and under cold rotary-swaging rates of 10% (b), 30% (c) and 40% (d)
Fig.9
Rotary-swaging rate
%
Rp0.2
MPa
Rm
MPa
A
%
Z
%
0
890.5
896.0
28.8
63.0
10
962.0
963.5
10.4
57.0
15
1045.0
1049.5
14.3
57.0
20
1087.0
1089.5
11.4
56.0
25
1128.5
1130.0
8.1
48.0
30
1146.0
1152.0
7.7
47.5
35
1206.0
1210.5
9.4
50.5
40
1191.5
1192.0
9.2
50.0
70
1350.0
1350.5
7.9
43.5
Table 1 Room temperature tensile properties of TB9 titanium alloy under different cold rotary-swaging rates
Fig.10 Distributions of grain size of TB9 titanium alloy under cold rotary-swaging rates of 10% (a), 35% (b) and 70% (c) with critical orientation angle 2o
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