(北京航空制造工程研究所 高能束流加工技术国家级重点实验室，北京100024)
摘 要: 基于原位观测技术，研究了钛合金电子束焊接接头的疲劳裂纹萌生行为，分析了接头组织不均匀对疲劳裂纹萌生的影响。结果表明：钛合金电子束焊接接头组织不均匀对疲劳裂纹萌生行为有一定的影响。在循环应力的作用下，焊缝区和热影响区的疲劳裂纹一般在试样表面边缘萌生；而在母材区，滑移除了在试样表面生成以外，也可能在α晶界上产生，但形成微裂纹并导致疲劳断裂的部位基本在表面滑移带上。母材区疲劳萌生寿命以及萌生寿命的分散性均比焊缝区和热影响区的好，母材区疲劳裂纹萌生寿命占总寿命的比例比焊缝区和热影响区的高。
关键字: 钛合金；电子束焊接；组织不均匀；疲劳；裂纹萌生
（National Key Laboratory of Science and Technology on Power Beam Processes,
Beijing Aeronautical Manufacturing Technology Research Institute, Beijing 100024, China）
Abstract:There are lamellar δ hydrides eutectoid generated in a manner of β→δ+α within β phase. Based on in-situ observation technology，the behaviour of fatigue crack initiation of titanium alloy electron beam weld joints was investigated, and the influence of microstructure heterogeneity of welded joints on the fatigue crack initiation behavior was analyzed. The results show that there are certain influence of microstructure heterogeneity of titanium alloy electron beam welded joints on the fatigue crack initiation behavior. Under the cyclic stress, the cracks of fusion zone or heat affects zone initiate from the surface edge or the stress concentration of the specimens, while the cracks of base metal initiated from the surface of the specimens or the grain boundary of α phase, but the formation of microcracks and location of fatigue fracture of base metal are basically on the surface persistent slip bands. The fatigue initiation life of base metal and its dispersion are better than those of fusion zone or heat affected zone. The proportion of crack initiation life in the total life of base metal is higher than that of fusion zone or heat affected zone.
Key words: titanium alloy; electron beam welding; microstructure heterogeneity; fatigue; crack initiation
