Microstructure and mechanical properties of annealed Ti−6Al−3Nb−2Zr−1Mo titanium alloys
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摘要: 采用模锻工艺及980 ℃退火工艺制备了Ti−6Al−3Nb−2Zr−1Mo合金，通过扫描电子显微镜（scanning electron microscope，SEM）观察和电子背向散射衍射（electron back-scattered diffraction，EBSD）分析等方法研究了退火态合金不同截面上的微观组织与力学性能。结果表明：与锻态合金比较，退火态Ti−6Al−3Nb−2Zr−1Mo合金的α相含量减少，亚稳态的β相增多。在空气冷却的过程中，合金的亚稳态β相又转化为次生α相和少量β相。退火态Ti−6Al−3Nb−2Zr−1Mo合金中α-Ti呈现出RD//[
$ \bar {1} $ 2$ \bar {1} $ 0]、FD//[0001]的织构类型（FD为锻件压缩方向（锻造方向），RD为锻件自由延伸方向）。退火态Ti−6Al−3Nb−2Zr−1Mo合金的三个方向拉伸断裂主要是韧性断裂，并且断裂方式呈现出微孔聚集断裂。沿RD方向拉伸时韧窝尺寸较大，对应的延伸率也优于其他方向。Abstract: Ti−6Al−3Nb−2Zr−1Mo alloys were prepared by forging and annealing at 980 ℃. The microstructure and mechanical properties of the annealed alloys on the different sections were studied by scanning electron microscopy (SEM) and electron back-scattered diffraction (EBSD). The results show that, compared with the forged alloys, the content of α phase in the annealed Ti−6Al−3Nb−2Zr−1Mo alloys decreases, and the content of the metastable β phase increases. During the cooling in the air, the metastable β phase is transformed into the secondary α phase and a small amount of β phase. After annealing at 980 ℃, α-Ti in Ti−6Al−3Nb−2Zr−1Mo alloys exhibits the texture types of RD//[$ \bar {1} $ 2$ \bar {1} $ 0] and FD//[0001], where RD is the forging compression direction (forging direction), and FD is the free extension direction of forging. The fracture morphology of Ti−6Al−3Nb−2Zr−1Mo alloys along the different tensile direction is mainly ductile fracture, and the fracture mode shows the micropore aggregation fracture. When the annealed alloys are stretched in RD direction, the size of the dimple is larger, and the corresponding elongation is superior to that in any other direction.-
Key words:
- titanium alloys /
- forging /
- annealing /
- mechanical properties /
- microstructure
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图 1 样品取向（a）和样品尺寸（b）示意图
Figure 1. Schematic diagram of the sample orientation (a) and geometry (b)
图 2 Ti−6Al−3Nb−2Zr−1Mo合金显微组织：（a）锻态合金；（b）退火态合金
Figure 2. Microstructure of the Ti−6Al−3Nb−2Zr−1Mo alloys: (a) forged alloys; (b) annealed alloys
图 3 退火态Ti−6Al−3Nb−2Zr−1Mo合金α-Ti微观组织形貌：（a）侧面；（b）断面
Figure 3. Microstructure of α-Ti in the annealed Ti−6Al−3Nb−2Zr−1Mo alloys: (a) broad side; (b) cross section
图 4 退火态Ti−6Al−3Nb−2Zr−1Mo合金取向成像图（IPF-Z）和反极图（IPF）：（a）侧面IPF-Z图；（b）断面IPF-Z图；（c）侧面IPF图；（d）断面IPF图
Figure 4. Orientation mapping (IPF-Z) and inverse pole figure (IPF) of the annealed Ti−6Al−3Nb−2Zr−1Mo alloys: (a) IPF-Z of broad side; (b) IPF-Z in cross section; (c) IPF of broad side; (d) IPF in cross section
图 5 退火态Ti−6Al−3Nb−2Zr−1Mo合金三个方向的拉伸曲线
Figure 5. Tensile curves of the annealed Ti−6Al−3Nb−2Zr−1Mo alloys in the different direction
图 6 退火态Ti−6Al−3Nb−2Zr−1Mo合金的三个方向塑性变形宏观形貌
Figure 6. Macro morphology of the annealed Ti−6Al−3Nb−2Zr−1Mo alloys after deformation in the different direction
图 7 退火态Ti−6Al−3Nb−2Zr−1Mo合金的三个方向拉伸断口形貌：（a）和（b）RD；（c）和（d）TD；（e）和（f）FD
Figure 7. Tensile fracture of the annealed Ti−6Al−3Nb−2Zr−1Mo alloys in the different direction: (a) and (b) RD; (c) and (d) TD; (c) and (f) FD
表 1 试验用钛合金锻造工艺
Table 1. Forging process of the titanium alloys
锻造次数 温度 / ℃ 保温时间 / min 1 1170 60 2 1100 3 1030 4 970 5 6 960 7 
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表 2 退火态Ti−6Al−3Nb−2Zr−1Mo合金三个方向的拉伸力学性能
Table 2. Mechanical properties of the annealed Ti−6Al−3Nb−2Zr−1Mo alloys in the different direction
方向 弹性模量 /
GPa屈服强度 /
MPa抗拉强度 /
MPa延伸率 /
%RD 109.9 754.4 843.5 16.3 TD 122.3 771.6 869.1 12.7 FD 107.7 776.9 889.1 10.0
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