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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 2022, Vol. 43 ›› Issue (4): 525223-525223.doi: 10.7527/S1000-6893.2021.25223

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Welding properties and molten pool flow behavior of TC4 titanium alloy by oscillating galvanometer laser

CHEN Bo1,2, MENG Zheng1, MA Chengyuan1, XI Xin1, WANG Xinxin3, TAN Caiwang1,2, SONG Xiaoguo1,2   

  1. 1. Shandong Provincial Key Laboratory of Special Welding Technology, Harbin Institute of Technology, Weihai, Weihai 264209, China;
    2. State Key Laboratory of Advanced Welding and Connection, Harbin Institute of Technology, Harbin 150001, China;
    3. Department of Mechanical Engineering, University College London, London SW75 NP, United Kingdom
  • Received:2021-01-06 Revised:2021-01-19 Published:2021-03-26
  • Supported by:
    National Key Research and Development Program (2018YFB1107900)

Abstract: Titanium alloys are widely used in aircraft and aerospace engines. Laser welding is an excellent welding method for joining titanium alloys, and the main problem currently existing is the degradation of joint performance due to porosity. Oscillating laser can significantly improve the keyhole behavior and molten pool flow state, thereby reducing porosity and refining grains, and eventually improving the joint properties in laser welding. Fiber laser was used to join the 4 mm thick TC4 titanium alloy using oscillating laser welding, and the weld formation, mechanical properties, grain refinement, molten pool flow and keyhole behavior before and after oscillating by 0.4 mm steps from 0.4 mm to 1.6 mm oscillating amplitude were compared and analyzed. The results show that keyhole-induced pores were significantly suppressed at a laser power of 4 kW, welding speed of 1.2 m/min, off-focus amount of 0, oscillating frequency of 100 Hz and oscillating amplitude of 0.8 mm, and the joint obtained can achieve the highest tensile strength of 1 025.03 MPa, which is 96% of that of the base material. Compared to the beam without laser oscillating, the upper grains of the joint with an oscillating amplitude of 0.8 mm were refined by 65%. The presence of circular laser oscillating caused the molten pool to be more stable, and gave directionality to the molten pool flow while the oscillating laser enlarged and stabilized the keyhole, reducing spatter and porosity.

Key words: laser welding, oscillating laser welding, mechanical property, grain refinement, molten pool flow, titanium alloy

CLC Number: