| 摘要: |
| 针对50mm厚TC4-DT钛合金开展了电子束焊接工艺试验，采用成组法和升降法分析研究了焊接接头的高周疲劳性能，并观察其微观组织与断口形貌。结果表明：大厚度TC4-DT钛合金电子束焊接接头具有良好的高周疲劳性能，其疲劳极限达到相同状态下母材的97.7%。焊接接头与母材疲劳寿命均存在分散性，主要与材料成分和组织的不均匀性有关。TC4-DT钛合金电子束焊接接头与母材的断口形貌显示，两种试样的疲劳裂纹均起源于试样表面。焊缝疲劳裂纹扩展区有明显的疲劳条带，瞬断区韧窝不明显，表现为脆性穿晶断裂，母材疲劳裂纹扩展区为有疲劳条带和一定数量的韧窝，瞬断区韧窝特征明显，为韧窝断裂。 |
| 关键词: TC4-DT钛合金 电子束焊 高周疲劳 |
| 基金项目: |
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| High Cycle Fatigue Properties of EBW Joint for Thick Section TC4-DT Titanium Alloy |
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Wang Jinxue Yuan Hong Yu Huai Zhang Guodong Li Jinying
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Beijing Institute of Aeronautical Materials, Beijing 100095
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| Abstract: |
| Electron beam welding experiments of 50mm thick section TC4-DT Titanium Alloy were carried out, then the high cycle fatigue properties, microstructure and the fatigue fractographies of the joint were studied with group method and up-and-down method. Results indicate that the high cycle fatigue properties of EBW joint for thick section TC4-DT titanium alloy are excellent, the fatigue limit of the joint achieves 97.7% of the basic metal. The fatigue life of the joint and basic metal are all dispered because of the heterogeneity of composition and microstructure. The fatigue fractographies of the joint and basic metal indicate that the fatigue cracks are initiated at the surface of the two kinds of specimens. Fatigue striations are observed in the fatigue crack growth region of the joint, the dimples are not observed in the fracture region and the mode of the fracture is brittle transcrystalline fracture. In the fatigue crack growth region of the basic metal, some dimples and fatigue striations are observed. Fracture region of the basic metal consists of a lot of dimples and the mode of fracture is dimple fracture． |
| Key words: TC4-DT titanium alloy EBW high cycle fatigue |
