Effect of oxygen content on microstructure and mechanical properties of TC4 ELI titanium alloy bar
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摘要: 采用自主制备的两种氧含量的TC4合金铸锭,通过开坯-锻造-退火等工艺制备出间隙元素含量远远低于GB/T 13810—2017及UNS R56401要求,性能优异的TC4 ELI钛合金棒材。通过化学分析、金相显微镜、拉伸试验和扫描电镜研究其性能,结果表明,经过开坯-锻造-退火,钛合金棒材氧氮氢等间隙元素含量较铸锭有较明显降低,其中氧含量均低于0.07%。棒材的力学性能受氧含量影响不大,强度及塑性较高,静态拉伸呈塑性断裂,棒材显微组织主要为均匀细化的等轴组织、双态组织及网篮组织。Abstract: By using two self-prepared TC4 alloy ingots with different oxygen content, the high-performance TC4 ELI titanium alloy bars are prepared by the processes of cogging-forging-annealing for interstitial impurities well below GB/T 13810—2017 and UNS R56401 requirements. The properties are investigated via chemical analysis, metallurgical microscopy, tensile tests and scanning electron microscopy (SEM). The results show that after process of blooming-forging-annealing, the contents of interstitial elements such as oxygen, nitrogen and hydrogen in titanium alloy bar are significantly lower than these in ingot, and the oxygen contents for two kinds of bar are less than 0.07%. The mechanical properties of the resulted bar are not affected by oxygen content, showing high strength and plasticity. The static tension shows plastic fracture. The microstructure of the bar is mainly composed of equiaxed, bimodal and basket-weave microstructure.
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Key words:
- TC4 ELI titanium alloy /
- bar /
- oxygen content /
- microstructure /
- tensile properties /
- fracture microstructure
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表 1 TC4 ELI铸锭化学成分
Table 1. Chemical compositions of TC4 ELI ingot
% 编号 部位 Fe O N H Al V Ti 铸锭1 上 0.03 0.100 0.006 0.0048 6.00 3.96 余量 中 0.02 0.107 0.018 0.0050 5.66 3.68 下 0.03 0.106 0.006 0.0048 5.91 3.88 铸锭2 上 0.02 0.045 0.008 0.0039 5.88 4.12 中 0.02 0.052 0.008 0.0040 5.81 4.17 下 0.02 0.040 0.008 0.0040 6.10 4.20 表 2 TC4 ELI钛合金端头及中段静态拉伸性能
Table 2. Static tensile properties of TC4 ELI titanium alloy end and middle sections
编号 Rp0.2/MPa Rm/MPa A/% Z/% 1-1-1 837 917 13.0 42 1-1-2 857 922 15.5 49 1-2-1 828 897 13.5 47 1-2-2 812 883 13.5 46 2-1-1 833 890 12.5 54 2-1-2 849 916 13.5 52 2-2-1 825 889 15.0 54 2-2-2 800 867 15.0 53 -
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