关键词: 钛合金;离心叶轮;裂纹扩展;人工缺陷;内部缺陷

Abstract: In order to obtain the crack growth characteristics of disk with artificial internal defects， the low-cycle fatigue crack propagation experiments under high-speed rotating condition were carried out on the disks with natural or artificial defect. Through the non-destructive testing analysis and fracture analysis， the difference of crack growth characteristics was studied， and the idea of damage tolerance analysis of disc with artificial defects is proposed. Nondestructive testing is easier to identify the artificial internal defects’ characteristics and its changes. The artificial defect area is fragmented， and has a lot of brittle intergranular， it is obviously different from the natural defect area， but there is no significant difference in the non-defect area. The crack growth rates in the natural and artificial defect areas are 0.2~0.4μm/cycle and 0.6~1.2μm/cycle， respectively， which are much higher than the theoretical value of the matrix material. The maximum error between the reverse life of the fracture outside the load mutation area of disc 1 and the cycle number in the second loading stage is 12%. The reverse life of the fracture outside the defect area of disc 2 accounts for 44.9%~51.9% of the total cycle number. Based on the artificial defect area， the initial crack of disk is defined to eliminate the influence of the difference between artificial and natural defects， so that the crack propagation characteristics of disk can be obtained by using artificial defects.

Key words: Titanium alloy;Centrifugal impeller;Crack propagation;Pre-set defect;Internal inclusion