Journal
OPTICS AND LASER TECHNOLOGY
Volume 80, Issue -, Pages 56-66Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.optlastec.2015.12.020
Keywords
GH909; Hybrid welding; Parameters; Microstructure; Mechanical properties
Categories
Funding
- Fund Program of China [51318050107]
- National Natural Science Foundation of China [51375191]
- National Program on Key Basic Research Project (973 Program) of China [2014CB046703]
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In this paper, laser-arc hybrid welding of 10 mm thick low-thermal-expansion superalloy GH909 components was carried out to obtain a joint with good performance. This investigation was conducted using an optical microscope, scanning electron microscope, energy diffraction spectrum and other methodologies. The results showed that weld joints with a desirable wineglass-shaped weld profile can be obtained employing appropriate process parameters. The different grains in between the upper central seam and the bottom seam were associated with the temperature gradient, the pool's flow and the welding thermal cycle. MC-type carbides and eutectic phases (gamma + Laves) were produced at grain boundaries due to the component segregation during the welding process. In addition, y' strengthening phase presented in the interior of grains, which kept a coherent relationship with the matrix. The lowest hardness value occurred in the weld center, which indicated that it was the weakest section in the whole joint. The average tensile strength of the joints reached to 632.90 MPa, nearly 76.84% of the base metal. The fracture analysis revealed that the fracture mode of the joint was ductile fracture and the main reason for joint failure was as a result of the occurrence of porosities produced in the weld during the welding process. (C) 2015 Elsevier Ltd. All rights reserved.
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