Effect of solution aging treatment on microstructure and properties of Ti60 alloy
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摘要: 通过光学显微镜和扫描电镜观察分析固溶时效处理对Ti60合金微观组织的影响，结合其室温及600 ℃高温拉伸分析得到：锻坯1/2高区域，组织较为均匀，适于在此取样开展Ti60合金固溶时效处理及后续性能研究。采用1035 ℃/2 h/WQ+700 ℃/5 h/AC固溶时效处理，Ti60合金的室温抗拉强度为1193 MPa，延伸率为6.7%；600 ℃高温抗拉强度达到751MPa，延伸率为20.3 %，具有较好的强塑性匹配。试样的裂纹源起源于试样中心部位，断面凹凸不平，为典型的韧窝型断裂；裂纹源在边部时，以爆炸式发散，断口均有明显的撕裂棱和解理面，断裂方式为脆性断裂。在600 ℃长时间暴露过程中，合金表面发生氧化，降低Ti60合金热稳定性及塑性。于600 ℃环境中考察Ti60合金长期稳定服役性能，Ti60合金锻态室温抗拉强度为1 064 MPa，延展率为9.4%；固溶时效后试样抗拉强度为1 224 MPa，延展率为4.7%。Abstract: The effect of solution and aging treatment on the microstructure of Ti60 alloy was investigated by optical microscope and scanning electron microscope. Combined with the tensile tests at room temperature and 600 ℃, it is found out the 1/2 height area of forged billet is relatively uniform and suitable for the study of solution aging treatment and subsequent mechanical properties of Ti60 alloy. After solution and aging treatment at 1 035 ℃/2 h/WQ+700 ℃/5 h/AC, the tensile strength of Ti60 alloy at room temperature is 1193 MPa and the elongation is 6.7%. While tested at 600 ℃, the tensile strength is 751 MPa and the elongation is 20.3%. When crack source originates from the center of the sample, and the fracture is uneven, which shows a typical dimple fracture. When the crack source locates on the edge, it diverges explosively and the fracture has obvious tearing edges and smooth surface, which exhibits a typical brittle fracture mode. After long duration heat exposure at 600 ℃, oxidation occurs on the alloy surface, which reduces the thermal stability and plasticity of Ti60 alloy. The long duration stable service performance of Ti60 alloy was investigated at 600 ℃. The tensile strength at room temperature of as-forged Ti60 alloy was 1 064 MPa, and the elongation rate was 9.4%.After solution aging, the tensile strength and elongation of obtained alloy are 1 224 MPa and 4.7%, respectively.
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Key words:
- Ti60 alloy /
- solution aging /
- fracture morphology /
- thermal stability
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图 2 固溶组织形貌
(a)边部，1 025 ℃; (b) 边部，1 035 ℃; (c) 边部，1 045 ℃; (d) 1/2，1 025 ℃; (e) 1/2，1 035 ℃; (f) 1/2，1 045 ℃; (g) 中心，1 025 ℃; (h) 中心，1 035 ℃; (i) 中心，1 045 ℃
Figure 2. Microstructure in different positions of Ti60 alloy after solution treatment at different temperatures
图 3 时效处理后的组织形貌
(a) 边部，1 025 ℃; (b) 边部，1 035 ℃; (c) 边部，1 045 ℃; (d) 1/2，1 025 ℃ ; (e) 1/2，1 035 ℃; (f) 1/2，1 045 ℃; (g) 中心，1 025 ℃; (h) 中心，1 035 ℃; (i) 中心，1 045 ℃
Figure 3. The microstructure in different positions of Ti60 alloy after aging treatment at different temperatures
图 4 室温拉伸试样断口形貌
I 1 025 ℃裂纹源；II 1 035 ℃裂纹源；III 1 045 ℃裂纹源；
Figure 4. Fracture morphology of tensile specimen deformed at room temperature for Ti60 alloy obtained after solution at different temperatures
(a) 300×, 1 025 ℃; (b) 300×, 1 035 ℃; (c) 300×, 1 045 ℃; (d) 1 000×, 1 025 ℃; (e) 1 000×, 1 035 ℃; (f) 1 000×, 1 045 ℃
图 6 热暴露试样组织形貌
(a)锻态; (b) 1 035 ℃/2 h+700 ℃/5 h
Figure 6. Microstructure of Ti60 alloy after thermal exposure at 600 ℃
图 7 热暴露试样室温拉伸断口
(a)锻态; (b)锻态, 300× ; (c)锻态, 1 000×; (d) 1 035 ℃/2 h+700℃/5 h; (e) 1 035 ℃/2 h+700 ℃/5 h, 300×; (f) 1035℃/2 h+700 ℃/5 h, 1 000×
Figure 7. Tensile fracture at room temperature for Ti60 alloy after thermal exposure
表 1 固溶时效后室温力学性能
Table 1. Mechanical properties of Ti60 alloy at room temperature after solution aging
固溶温度/℃ Rm/MPa Rp0.2/MPa A/% 锻态 1041 946 6.8 1025 1070 981 9.8 1035 1193 1094 6.7 1045 1187 1083 7.9 
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表 2 固溶时效后600 ℃高温力学性能
Table 2. Mechanical properties of Ti60 alloy deformed at 600 ℃ after solution aging
固溶温度/℃ Rp0.2/MPa Rm/MPa A/% Z/% 1025 574 735 25 72 1035 587 751 20.3 66 1045 576 740 24 68
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表 3 热暴露试样室温力学性能
Table 3. Mechanical properties at room temperature of Ti60 alloy after thermal exposure
样品 Rm/MPa Rp0.2/MPa A/% 锻态 1064 1002 9.4 1035 ℃/2 h+700 ℃/5 h 1224 1034 4.7
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