The ultrasonic vibration (UV) assisted laser welding was employed to weld Inconel 690 alloy. The microstructure evolution, the tensile strength, the elongation and the fracture behavior of the weld joint were studied through a scanning electron microscopy, an electron back-scatter diffraction and a universal testing machine. The results indicated that there produced an equiaxed crystal region in the center of the weld joint where a great deal of the low angle grain boundary distributed due to the cavitation effect caused by adding the UV. In addition, the proportion of the equiaxed crystal tended to increase, the grain size seemed to be finer. Moreover, the tensile strength and the elongation of the weld joint with UV were significantly improved with an increase in the UV because of the grain refinement. The maximum tensile strength increased to be the same as that of the matrix, and the maximum elongation was about 70% of that of the matrix. The joint without UV fractured with necking, nevertheless, the fracture of joint with UV occurred in the dendrite region of the weld joint and happened in the direction of 45° to the tensile direction due to the appearance of the similar direction between slip surface and the direction of the maximum shear stress, and the change in Taylor factor and Schmid factor distribution of the dendrite in the weld joint. Besides, the ductile fracture was still the main fracture feature because of the formation of the dimples and micro-voids.

超声波振动 (UV) 辅助激光焊接用于焊接 Inconel 690 合金。通过扫描电子显微镜、电子背散射衍射和万能试验机研究了焊缝的微观组织演变、抗拉强度、延伸率和断裂行为。结果表明，由于加入紫外光引起的空化效应，在焊缝中心产生了等轴晶区，该区分布着大量低角度晶界。此外，等轴晶所占比例有增加的趋势，晶粒细化。此外，由于晶粒细化，随着 UV 的增加，UV 焊缝的抗拉强度和伸长率显着提高。最大抗拉强度增加到与基体相同，最大伸长率约为基体的70%。没有UV的接头发生颈缩断裂，而有UV的接头断裂发生在焊缝的枝晶区，且由于滑移面与焊缝的方向相似，发生在与拉伸方向成45°的方向。最大剪应力的方向，以及焊缝中枝晶的泰勒因子和施密特因子分布的变化。此外，由于韧窝和微孔洞的形成，韧性断裂仍然是主要断裂特征。UV接头断裂发生在焊缝的枝晶区，且发生在与拉伸方向成45°的方向，这是由于滑移面与最大剪应力方向的相似方向的出现，以及变化焊缝中枝晶的泰勒因子和施密特因子分布。此外，由于韧窝和微孔洞的形成，韧性断裂仍然是主要断裂特征。UV接头断裂发生在焊缝的枝晶区，且发生在与拉伸方向成45°的方向，这是由于滑移面与最大剪应力方向的相似方向的出现，以及变化焊缝中枝晶的泰勒因子和施密特因子分布。此外，由于韧窝和微孔洞的形成，韧性断裂仍然是主要断裂特征。