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合理的热处理制度能显著影响β钛合金的显微组织和强化行为。通过对一种新型Ti-Al-V-Mo-Cr-Zr-Nb-Fe亚稳β钛合金的固溶时效处理,研究了热处理工艺对该合金组织与力学性能的影响。结果表明:该合金720℃固溶处理后,可以获得单一均匀的等轴β晶粒,为最佳固溶温度;经440~520℃时效处理后,发现时效温度对该新型合金α相析出的形态与尺寸的影响显著:在较低温度440℃时效时β基体上有针状α相析出,平均晶粒尺寸在1~2μm左右;较高温度520℃时效时,α相宽度和片层间距都增大,α相尺寸长大到3~5μm,针状α相向短棒状转化。在实验温度范围内,随着时效温度升高,合金强度降低,塑性增加。720℃固溶较低温度时效合金可获得较好的强度与韧性匹配。该合金理想的热处理工艺参数为720℃/30 min、空冷(AC)+440℃/12 h、空冷(AC),由此可获得到良好的综合性能(抗拉强度UTS=1412.8 MPa,屈服强度YS=1309.4 MPa,延伸率A=8.56%,断面收缩率Z=44.94%)。
Reasonable heat treatment system can significantly affect the β-titanium alloy microstructure and strengthening behavior. The effect of heat treatment on microstructure and mechanical properties of a new type of Ti-Al-V-Mo-Cr-Zr-Nb-Fe metastable β titanium alloy was studied. The results show that the alloy has a uniform and equiaxial β grain size after solution treatment at 720 ℃ for the optimum solution temperature. After the aging treatment at 440-520 ℃, it is found that the aging temperature precipitates the α phase of the new alloy The influence of shape and size is remarkable: the acicular α phase precipitates on the β matrix at the lower temperature of 440 ℃, the average grain size is about 1 ~ 2μm; when the aging temperature is 520 ℃, the α phase width and the spacing Both increase, the α-phase size grows to 3 ~ 5μm, needle-like α-shaped short rod-like transformation. In the experimental temperature range, with the aging temperature, alloy strength decreased, plasticity increased. 720 ℃ solid solution lower temperature aging alloys get better strength and toughness match. The ideal heat treatment process parameters of the alloy are 720 ℃ / 30 min, AC + 440 ℃ / 12 h, air cooling (AC), so that good comprehensive properties can be obtained (tensile strength UTS = 1412.8 MPa, yield strength YS = 1309.4 MPa, elongation A = 8.56%, cross-sectional shrinkage Z = 44.94%).