Influence of Laser Power on Grain Size and Tensile Strength of 5A90 Al–Li Alloy T-joint Fabricated by Dual Laser-Beam Bilateral Synchronous Welding

  • Shuai Chen
  • Xiaohong ZhanEmail author
  • Yanqiu Zhao
  • Youfa Wu
  • Dongtao Liu


Dual laser-beam bilateral synchronous welding is introduced to produce the 2.5 mm thick 5A90 Al–Li alloy T-joint. The grain morphology and grain size of weld metal (WM) in the T-joint are analyzed and calculated. The tensile experiment, scanning electron microscopy and energy disperse spectroscopy are respectively employed to study the tensile strength, fracture morphology and chemical composition of the T-joint. The results reveal that when the laser power is increased from 2500 to 3000 W, the grain sizes of fine-grained layers and columnar dendrites near the fusion line are significantly reduced. Conversely, that of equiaxed dendrites at the WM center is not sensitive to the variety of laser power. Moreover, the degree of elemental segregation in WM near the fusion line is also aggravated with the increasing of the laser power. The tensile strength of the T-joint with the laser power of 2500 W is significantly higher than that with the laser power of 3000 W. The tensile fracture locations are occurred in the weld toe with obvious pores, shear dimples and tear ridges, which are the typical characteristics of ductile fracture. Besides, the chemical compositions of the second phase particles in the WM are more sensitive to than the variation of laser power compared with that of the matrix.

Graphic Abstract


DLBSW 5A90 Al–Li alloy T-joint Gain size Tensile strength 



The authors gratefully acknowledge the financial support of the project from the National Natural Science Foundation of China (U1637103).


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Copyright information

© The Korean Institute of Metals and Materials 2019

Authors and Affiliations

  • Shuai Chen
    • 1
  • Xiaohong Zhan
    • 1
    Email author
  • Yanqiu Zhao
    • 1
  • Youfa Wu
    • 1
  • Dongtao Liu
    • 2
  1. 1.National Key Laboratory of Science and Technology on Helicopter TransmissionNanjing University of Aeronautics and AstronauticsNanjingChina
  2. 2.Laser Equipment and Process Technology R&D CenterNanjing Institute of Advanced Laser TechnologyNanjingChina

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