脉冲电流频率对预制缺陷TC4钛合金性能的影响

为了研究脉冲电流频率对预制缺陷TC4钛合金组织性能的影响规律,首先采用室温预拉伸制备含孔洞缺陷的TC4试样,然后选取不同频率的脉冲电流对预制缺陷的TC4试样进行通电处理,对比通电前后板材内部的显微孔洞和基体组织的变化情况,并对处理后的试样进行二次室温拉伸获得力学性能参数。结果表明：当脉冲电流频率从0升至140Hz时,TC4内部孔洞体积分数由2.21%下降至0.86%,屈服强度由916.7MPa提高到990.9MPa,抗拉强度由951.2MPa增加至997.5MPa,延伸率提高64.86%；当脉冲电流频率从140Hz提高到160Hz时,内部孔洞体积分数反而增至1.99%,屈服强度和抗拉强度则分别下降到975.1MPa和988.5MPa,延伸率降低了37.70%。显微孔洞体积分数几乎决定了预制缺陷TC4钛合金的力学性能。

Effect of Pulse Current Frequency on Mechanical Properties of TC4 Titanium Alloy with Prefabricated Defects

In order to study effect of pulse current frequency on microstructure and mechanical properties of TC4 titanium alloys with prefabricated defects, TC4 specimens with void defects were firstly prepared by pre-stretching at room temperature and then treated by pulse current with different frequencies. Microstructural variations of void and matrix before and after pulse current treatment were compared. Mechanical properties were obtained by second room-temperature tension. The results indicate void volume fraction decreases from 2.21% to 0.86% when pulse frequency increases from 0 to 140Hz. Meanwhile, yield strength and ultimate tensile strength rise from 916.7MPa to 990.9MPa and from 951.2MPa to 997.5MPa, respectively. Moreover, the elongation increases by 64.86%. However, void volume fraction increases to 1.99% when pulse frequency increases from 140Hz to 160Hz. At the same time, yield strength and ultimate tensile strength decrease to 975.1MPa and 988.5MPa, separately. The elongation decreases by 37.70%. Void volume fraction almost determines mechanical properties of TC4 alloys with prefabricated defects.