显微组织对TC21合金疲劳性能的影响

Influence of Microstructure on Fatigue Properties of TC21 Alloy

选取实际工业生产的TC21钛合金锻件,研究不同部位的显微组织、动静态力学性能并疲劳断口形貌.结果表明:TC21钛合金经过准β锻造后显微组织为网篮组织,其组织中存在未完全破碎的晶界α相,锻件头部、中部和尾部的组织有一定的差异.不同部位锻件均能获得良好的拉伸性能,且拉伸性能稳定.R=0.06时,头部、中部和尾部样品的疲劳极限分别是704.2 MPa、698.8 MPa和662.5 MPa.原始晶界α的破碎程度影响材料的高周疲劳性能,显微组织中存在粗大的α片层会导致其疲劳性能降低.在实际生产过程优化锻造工艺,改善在锻件不同部位的显微组织会提高TC21锻件的疲劳性能.

In this paper,the microstructure,dynamic and static mechanical properties and fatigue fracture morphology of different parts of TC21 titanium alloy forgings were studied.The results show that the microstructure of TC21 alloy forging by quasi-βforging is basket structure,and there are originalα-grain boundaries which are not completely broken.The microstructure of forging head,middle and tail is different.Good tensile properties can be obtained in different parts of forgings,and the tensile properties are stable.When R=0.06,the fatigue limits of head,middle and tail samples are 704.2 MPa,698.8 MPa and 662.5 MPa respectively.The fracture degree of original grain boundaryαaffects the high cycle fatigue property of the material,and the existence of coarseαlamellae in the microstructure will lead to the decrease of the fatigue property.In the production process,optimizing the forging process and improving microstructure in different parts of the forging will improve the fatigue performance of TC21 forging.