TC4钛合金扩散连接接头的振动疲劳特性及劣化机理  

Vibration fatigue properties and deterioration mechanism of diffusion bonded TC4 titanium alloy

作　　者：雷奕文 马广璐 刘悦 赵伟[2] 吴会平 李细锋 Yi-wen LEI;Guang-lu MA;Yue LIU;Wei ZHAO;Hui-ping WU;Xi-feng LI(Institute of Forming Technology&Equipment,School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 200030,China;AECC Shenyang Liming Aero Engine(Group)Co.,Ltd.,Shenyang 110043,China)

机构地区：[1]上海交通大学材料科学与工程学院塑性成形技术与装备研究院,上海200030 [2]沈阳黎明航空发动机有限责任公司,沈阳110043

出　　处：《Transactions of Nonferrous Metals Society of China》2024年第2期533-546,共14页中国有色金属学报（英文版）

基　　金：support from the National Natural Science Foundation of China(Nos.51875350,52105383).

摘　　要：为了研究扩散连接工艺对材料振动疲劳特性的影响,对扩散连接后的TC4钛合金和原始母材进行一系列振动疲劳试验以及显微组织表征。结果表明:扩散连接的热循环过程引起TC4钛合金显微组织变化,并导致其振动疲劳性能降低。经扩散连接后,TC4钛合金晶粒尺寸的不均匀性增加,加重了材料不同取向α晶粒间的不协调变形,从而使微孔洞易于在晶粒尺寸差异较大的两α晶粒的晶界上萌生,或者在较大α晶粒的内部萌生。同时,扩散连接后材料α晶粒取向的变化使得柱面滑移系更易被启动,促进了裂纹更早地萌生。此外,扩散连接后TC4钛合金β相含量的增加为微孔洞提供了更多的形核位置。因此,由扩散连接热循环过程造成的晶粒尺寸不均匀性增加、晶粒取向变化和β相含量增加使扩散连接TC4钛合金的振动疲劳性能劣化。To analyze the effect of diffusion bonding process on vibration fatigue properties,a series of fatigue tests and microstructure characterization of as-received and diffusion bonded TC4 titanium alloy were conducted.The results show that the thermal cycling of diffusion bonding process results in microscopic change and deteriorates vibration fatigue lifetime of TC4 alloy.For bonded TC4 alloy,the increased grain size inhomogeneity stimulates incompatible deformation of differently orientedαgrains and leads to micro-void formation at boundaries of small/largeαgrain pairs or inside largeαgrains.Meanwhile,the orientation variation ofαgrains promotes activation of prismatic slip systems for earlier crack initiation.In addition,the increased fraction ofβphase provides more nucleation locations for micro-voids.Thus,the increase of the grain size inhomogeneity,grain orientation change,and the increase ofβphase fraction due to the thermal cycling result in fatigue performance deterioration of diffusion bonded TC4 titanium alloy.

关 键 词：扩散连接 振动疲劳 热循环 TC4钛合金 

分 类 号：TG146.23[一般工业技术—材料科学与工程]