中文摘要：

对0.5 mm厚Hastelloy C-276薄板激光焊接接头进行疲劳试验,结合应力-寿命（S-N）曲线和疲劳断口形貌,研究母材及焊接接头的疲劳性能,分析母材和焊接接头的疲劳断裂机理。结果表明：0.5 mm Hastelloy C-276薄板焊接接头和母材的S-N曲线斜率基本相同,焊接接头疲劳性能和母材的基本相当;母材疲劳断口疲劳裂纹起源于试样侧表面,主要沿宽度方向扩展,随着应力的减小,疲劳源数目减少,疲劳裂纹扩展速率减小;焊接接头在母材和焊缝处随机断裂,焊接接头母材区断口形貌和母材断口形貌基本一致,而焊接接头焊缝区断口的疲劳裂纹起源于侧表面棱角处和焊缝表面,焊缝表面是主要疲劳源,裂纹主要沿厚度方向进行扩展,疲劳裂纹扩展区呈现出准解理断裂特征。

英文摘要：

Fatigue test was conducted on the laser welded joints of 0.5 mm thick Hastelloy C-276 thin sheet. The fatigue properties and fatigue fracture mechanism were investigated by S-N curves and fatigue fracture morphology of the base metal and the weld joint. The results show that the slopes of S-N curves of the laser welded joints and base metal are basically the same and the fatigue properties of the laser welded joints are almost equal to those of the base metal. The fatigue crack of base metal originates from the side surface of samples and propagates along the width direction of fatigue fracture. As the stress decreases, the number of fatigue sources decreases, and the fatigue crack growth rate also decreases Fatigue fractures of laser welded joints distribute in the base metal and the weld zone randomly, and the fatigue fracture macro morphology of the weld joint fractured in the base metal is basically identical to that of the base metal. The fatigue crack of weld joint fractured in the weld zone originates from the edge of side surface and the weld surface, the latter is the main fatigue source. The crack propagates along the thickness direction of fatigue fracture. Fatigue crack propagation area of the weld zone fracture presents quasi-cleavage fracture.