Correlation between structure and orientation of TC17 titanium alloy during thermal deformation and heat treatment
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摘要: 為了進一步研究熱壓縮及熱處理過程對組織及取向變化的關聯性, 通過對TC17進行熱壓縮變形及后續熱處理, 利用光學顯微鏡和背散射電子衍射等分析方法, 結合晶粒尺寸、織構分布圖、極圖以及反極圖, 研究變形后及熱處理后的TC17的組織結構、晶粒尺寸的變化和取向的演變規律以及兩者之間的關聯性.結果表明: 隨著變形溫度升高, 初生α相含量大幅減小, 尺寸減小, 大部分α相晶粒分散分布, 且位于高溫β相晶粒的三叉晶界上; 熱處理后, α相和β相組織特征清晰, 界限明顯, 初生α相依舊存在, 且趨于等軸化, 亞穩定β相發生轉變, 形成片層狀β轉變組織; 熱變形使α相織構極密度值減小, 且隨之溫度增加, α相織構極密度值也變小; 熱變形后的α相已不存在明顯的強織構, 熱變形對α相晶粒的取向影響較大, 很明顯的改善了其取向的均勻性; 熱變形同樣使β相織構極密度值減小, 但效果不明顯.β相仍存在取向集中現象, 取向均勻性相對較差.Abstract: In the previous studies on the microstructure and orientation of titanium alloys, the microstructural and orientational evolution of typical titanium alloys during thermal compression have been studied in depth. However, studies of the correlation between hot compression and heat treatment processes on microstructural and orientational changes have been few. It is of great significance to further study this correlation during hot treatment. For this study, during hot compression deformation and subsequent hot treatment of TC17 titanium alloy on a thermal simulator using cylindrical specimens, the microstructure, grain size change, and orientation evolution of TC17 were studied using optical microscopy and backscattered electron diffraction analysis. Grain size, texture distribution, pole figure, and reverse polarity were analyzed. Law and the relation between structure and orientation results show that the primary α-content decreases dramatically and size decreases in tandem with deformation temperature. Most of the α phase grains are dispersed and located on the trigeminal grain boundaries of the high temperature β phase grains. After heat treatment, the α phase and β phase had a clear structure and distinct boundary. The primary α phase still exists and tends to be equiaxed, and the metastable β phase changes formed a lamellar β-transformed structure. The hot deformation reduces the density of the α phase texture. Additionally, with increasing temperature, the density value of the α phase texture also becomes small. The α phase is no longer strongly textured after thermal deformation, and the orientation of the α phase grains is considerably influenced by thermal deformation, which clearly improves the uniformity of orientation. The thermal deformation also reduces the texture polar density value of the β phase, but the effect is not obvious. However, there is still a density of orientation, and the uniformity of the orientation is relatively poor.
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Key words:
- TC17 titanium alloy /
- phase content /
- grain size /
- orientation uniformity
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圖 2 TC17合金在不同溫度下0.01 s-1熱壓縮變形組織. (a) 840℃; (b) 860℃; (c) 880℃
Figure 2. Microstructure of the TC17 alloy hot compressed at 0.01 s-1and different temperatures: (a) 840℃, (b) 860℃, (c) 880℃
圖 3 TC17合金在860℃下不同應變速率下熱壓縮變形組織. (a) 0.01 s-1; (b) 0.1 s-1; (c) 1 s-1
Figure 3. Microstructure of the TC17 alloy hot compressed at 860℃and different strain rates: (a) 0.01 s-1, (b) 0.1 s-1, (c) 1 s-1
圖 4 TC17合金熱處理后的微觀組織. (a) 840℃, 0.1 s-1; (b) 860℃, 0.1 s-1; (c) 880℃, 0.1 s-1; (d) 860℃, 0.01 s-1; (e) 860℃, 1 s-1
Figure 4. Microstructure of the TC17 alloy heat treated at different conditions: (a) 840℃, 0.1 s-1; (b) 860℃, 0.1 s-1; (c) 880℃, 0.1 s-1; (d) 860℃, 0.01 s-1; (e) 860℃, 1 s-1
圖 5 熱變形前后TC17合金α相的取向分布. (a) 熱壓縮前; (b) 860℃, 0.01 s-1; (c) 840℃, 0.1 s-1; (d) 860℃, 0.1 s-1; (e) 880℃, 0.1 s-1; (f) 860℃, 1 s-1
Figure 5. αphase orientation distribution of the TC17 alloy before and after hot compression: (a) before hot compression; (b) 860℃, 0.01 s-1; (c) 840℃, 0.1 s-1; (d) 860℃, 0.1 s-1; (e) 880℃, 0.1 s-1; (f) 860℃, 1 s-1
圖 6 熱變形前后TC17合金β相的取向分布. (a) 熱壓縮前; (b) 860℃, 0.01 s-1; (c) 840℃, 0.1 s-1; (d) 860℃, 0.1 s-1; (e) 880℃, 0.1 s-1, (f) 860℃, 1 s-1
Figure 6. β-phase orientation distribution of the alloy before and after hot compression: (a) before hot compression; (b) 860℃, 0.01 s-1; (c) 840℃, 0.1 s-1; (d) 860℃, 0.1 s-1; (e) 880℃, 0.1 s-1; (f) 860℃, 1 s-1
圖 7 TC17合金在0.1 s-1應變速率不同溫度下變形后經熱處理的β相的取向分布圖. (a) 840℃; (b) 860℃; (c) 880℃
Figure 7. IPF diagram of theβphase of TC17 alloy after deformation at different temperatures of 0.1 s-1strain rate: (a) 840℃; (b) 860℃; (c) 880℃
圖 8 TC17合金在0.1 s-1應變速率不同溫度下變形的α相的極圖. (a) 840℃; (b) 860℃; (c) 880℃
Figure 8. Electrode diagram of theαphase of TC17 alloy deformed at different temperatures and 0.1 s-1strain rate: (a) 840℃; (b) 860℃; (c) 880℃
圖 9 TC17合金在0.1 s-1應變速率不同溫度下變形的β相的極圖. (a) 840℃; (b) 860℃; (c) 880℃
Figure 9. Polar diagram of theβphase of TC17 alloy at different temperatures at 0.1 s-1strain rate: (a) 840℃; (b) 860℃; (c) 880℃
圖 10 TC17合金熱處理過程中次生α相與β相的取向關系
Figure 10. Orientation of secondary phase and spur phase in the TC17 alloy heat treatment process
中文字幕在线观看表 1 TC17合金的主要化學成分(質量分數)
Table 1. Main chemical compositions of TC17 alloy ?
% Al Cr Mo Sn Zr Fe C Si H O Ti 5.02 3.93 3.88 2.37 1.95 0.05 0.01 — 0.003 0.12 余量 
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