TC17钛合金压气机鼓筒篦齿裂纹分析研究

发动机第二寿命期到寿后返厂大修，在进行荧光检测时，发现TC17钛合金的高压压气机一、二级盘组合件连接鼓筒的三道封严齿处出现宏观裂纹。通过对连接鼓筒裂纹的分布、形态及走向进行宏、微观分析，并对裂纹打开断口进行分析，以及检查鼓筒周向4个位置的封严齿处的磨损及烧伤情况，结果表明:高压压气机一、二级盘鼓筒裂纹性质为疲劳开裂；疲劳裂纹产生的原因是封严环篦齿与蜂窝环设计间隙过小，发动机工作时出现严重对磨，产生高温，磨损导致的温升由于钛合金导热率低而不能及时传导，导致齿顶基体组织出现过热甚至过烧现象，材料性能下降，在发动机高速旋转时的对磨应力作用下，疲劳裂纹萌生和扩展。通过放宽封严环篦齿和蜂窝环之间的设计间隙，适当的改善蜂窝环的制造工艺，降低蜂窝环硬度，从而解决了此类故障。

Crack Analysis of Compressor Drum Seal Teeth of TC17 Titanium Alloy

An engine was sent back to factory for repairing after its second service time limit. Crack was macroscopically visible in three seal teeth between drum and frist- and second-grade discs during florescence detection on the high-pressure compressor of TC17 titanium alloy. In order to find out the failure cause, the distribution, morphology and direction of the crack were observed, the crack fracture was analyzed, and the degree of wear and burn of 4 seal teeth along the circumference of the connecting drum was inspected. The results show that the cracking mode is fatigue cracking. The reason for the fatigue crack is that the designed clearance between seal teeth and honeycomb ring is too small, so a great deal of heat was emitted because of severely grinding while the engine worked. The thermal conductivity of titanium alloy is low, so the heat could not be transmitted in time, resulting in the overheating and even overburning of teeth top as well as the weakening of their properties. The fatigue crack initiated and propagated due to the grinding stress of high-speed rotation of engine. Such a problem can be solved by widening the designed clearance between seal teeth and honeycomb ring, improving the manufacturing technique and lowering the hardness of honeycomb ring.