Kang Minjung, Han Heung Nam, Kim Cheolhee
Welding and Joining Research Group, Korea Institute of Industrial Technology, 7-47, Songdodong, Yeonsugu, Incheon 21999, Korea.
Department of Materials Science and Engineering and RIAM, Seoul National University, Seoul 08826, Korea.
Materials (Basel). 2018 Apr 23;11(4):648. doi: 10.3390/ma11040648.
Oscillating laser beam welding for Al 6014 alloy was performed using a single mode fiber laser and two-axis scanner system. Its effect on the microstructural evolution of the fusion zone was investigated. To evaluate the influence of oscillation parameters, self-restraint test specimens were fabricated with different beam patterns, widths, and frequencies. The behavior of hot cracking propagation was analyzed by high-speed camera and electron backscatter diffraction. The behavior of crack propagation was observed to be highly correlated with the microstructural evolution of the fusion zone. For most oscillation conditions, the microstructure resembled that of linear welds. A columnar structure was formed near the fusion line and an equiaxed structure was generated at its center. The wide equiaxed zone of oscillation welding increased solidification crack susceptibility. For an oscillation with an infinite-shaped scanning pattern at 100 Hz and 3.5 m/min welding speed, the bead width, solidification microstructure, and the width of the equiaxed zone at the center of fusion fluctuated. Furthermore, the equiaxed and columnar regions alternated periodically, which could reduce solidification cracking susceptibility.
采用单模光纤激光器和两轴扫描系统对6014铝合金进行了摆动激光束焊接。研究了其对熔合区微观组织演变的影响。为了评估摆动参数的影响，制作了具有不同光束模式、宽度和频率的自拘束试样。通过高速摄像机和电子背散射衍射分析了热裂纹扩展行为。观察到裂纹扩展行为与熔合区的微观组织演变高度相关。在大多数摆动条件下，微观组织类似于线性焊缝。在熔合线附近形成柱状组织，在其中心生成等轴组织。摆动焊接的宽等轴区增加了凝固裂纹敏感性。对于100 Hz和3.5 m/min焊接速度下无限形状扫描模式的摆动，焊缝宽度、凝固微观组织以及熔合中心等轴区的宽度会发生波动。此外，等轴区和柱状区周期性交替，这可以降低凝固裂纹敏感性。
