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| Influence of Interface Defect on High Cycle Fatigue Behaviour of Titanium Alloy Diffusion Bonding Joint |
| DENG Wujing 1,2,3, SHAO Jie 1,2,3, CHEN Wei1 , LI Zhiqiang 1,2,3, LI Xiaohua 1,2,3 |
| ( 1. AVIC Manufacturing Technology Institute, Beijing 100024, China; 2. Aeronautical Key Laboratory for Plastic Forming Technologies, Beijing 100024, China; 3. Beijing Key Laboratory of Digital Plasticity Forming and Equipment, Beijing 100024, China ) |
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Abstract Joints of Ti–6Al–4V alloy with non-defect、ϕ2mm diameter、ϕ4mm diameter and penetrating defect were artificially fabricated by diffusion bonding (DB) process. The effects of interface defects on high-cycle fatigue properties of bonding joints are quantificationally investigated using the tension-compression fatigue tests (R=–1) while the defect plane is parallel to the load axis. Results indicate that the high cycle fatigue (HCF) limit of joints with non-defect and ϕ2mm diameter have simultaneously reached to 410MPa, while HCF limit of joints with penetrating defect alloy has fallen to 315MPa. Compared with other defect couples, joints with ϕ4mm DB defect shows a larger scatter of life that HCF strength doesn’t converge. Meanwhile defects have influenced on fatigue initiation location that fatigue crack of couples with nondefect mainly initiate from out-surface and fatigue crack of couples with penetrating defect mainly initiate from subsurface. Fatigue samples with ϕ4mm defect initiated surface exhibited longer fatigue life; While almost all samples with defect-induced crack initiation exhibited a much shorter fatigue life.
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2020, 
