低温对时效态TC4合金拉伸性能的影响

在77－300K温度范围内对不同时6效状态TC4合金进行拉伸试验，研究了低温对时效态合金拉伸性能的影响。时效温度取813天，时效时间分别为0．5h、7h、60h。试验结果表明：在室温下，时效0．5h合金与退火态合金相比强度明显提高，延伸率略有降低；时效时间大于0．5h，随时效时间的延长，合金的强度与延伸率均下降。随试验温度的降低，3种时效态合金的强度都单调增加，延伸率先是下降，但在77K时又略有升高，TEM观察表明，随着试验温度的降低，拉伸断口附近位错分布不均匀性增大。

Effect of low temperature on tensile properties of aged TC4 alloy

The tensile tests at the temperatures ranged from 77 to 300K were carried out for differently aged TC4 alloys. The effect of low temperature on tensile properties of the aged alloys was studied. The aging temperature was chosen as 813K and the aging time as 0 5h, 7h and 60h respectively. Results show that, at the room temperature, compared with the annealed alloy, the strength of the alloy aged for 0 5h is much higher and its elongation is slightly lower. Under the case of the aging time over 0 5h, the strength and elongation of the alloy are decreased with increasing the aging time. With decreasing the testing temperature, the strengths of the three aged alloys are monotonously increased and the elongations are firstly decreased, but slightly increased at 77K. TEM observations show that with decreasing the temperature, the inhomogeneity of the dislocation distribution near tensile fracture surfaces is increased.