Hamed Zargari Habib, Ito Kazuhiro, Miwa Tsuyoshi, Parchuri Pradeep Kumar, Yamamoto Hajime, Sharma Abhay
Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Osaka 567-0047, Japan.
Department of Mechanical and Aerospace Engineering, Indian Institute of Technology Hyderabad, Sangareddy, Telangana 502285, India.
Materials (Basel). 2020 Jul 10;13(14):3096. doi: 10.3390/ma13143096.
Tandem-pulsed gas metal arc welding (TP-GMAW) simultaneously uses two wire-electrodes to enhance the material deposition rate, leading to the generation of a finger-shaped penetration as one of the arcs penetrates deeper than the other. On the other hand, workpiece vibration is one of the techniques used to control the microstructure of weld metal and a heat-affected zone. It is incidentally found that a specific vibration condition changes the finger-shaped penetration into pan-bottom shaped penetration in the TP-GMAW even though the vibration energy is much lower than the arc energy. Microstructure observation and elemental analysis are carried out for the welds fabricated without vibration and with three kinds of vibration modes, namely sine, random, and shock. The specific sine-mode vibration exhibits pan-bottom. The other modes of vibration in the same welding conditions exhibited invariable finger-shaped penetration. The Si atoms as a tracer distribute uniformly in the sine-mode. However, Si atoms segregate at the bottom of the finger-shaped weld metal with the random-mode and shock-mode workpiece vibrations. The weld pool shape change is prominent at a specific frequency. A resonance phenomenon between the droplet flow pattern and the molten material flow in the weld pool is likely to play a vital role in the change.
串联脉冲气体保护金属极电弧焊（TP-GMAW）同时使用两根焊丝电极来提高材料沉积速率，由于其中一个电弧比另一个电弧穿透更深，从而产生指状熔深。另一方面，工件振动是用于控制焊缝金属和热影响区微观结构的技术之一。偶然发现，即使振动能量远低于电弧能量，特定的振动条件也会使TP-GMAW中的指状熔深变为锅底形熔深。对无振动以及采用正弦、随机和冲击三种振动模式所制备的焊缝进行了微观结构观察和元素分析。特定的正弦模式振动呈现出锅底形。在相同焊接条件下的其他振动模式呈现出不变的指状熔深。作为示踪剂的硅原子在正弦模式下均匀分布。然而，在随机模式和冲击模式的工件振动下，硅原子在指状焊缝金属底部偏析。在特定频率下，熔池形状变化显著。熔滴流动模式与熔池内熔融材料流动之间的共振现象可能在这种变化中起关键作用。
