1 Aerospace Research Institute of Materials and Processing Technology, Beijing 100076, China 2 Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China 3 AECC Beijing Institute of Aeronautical Materials, Beijing 100095, China
Inconel 617 nickel-based superalloy with 3 mm wall thickness was welded by laser beam using two different heat input welding parameters. The microstructure of the welded joint was observed by optical microscope and scanning electron microscope, and the mechanical properties of the welded joint at room temperature (25℃) and high temperature (900℃) were tested. The results show that the laser welding heat input has a significant effect on the microstructure and mechanical properties of Inconel 617 welded joints. The front width of the laser weld obtained by high heat input (200 J/mm) process parameters is 3.88 mm. The grain size in the middle of the weld fusion zone is coarse, and the grain orientation is disordered. The secondary dendrite arm spacing in the middle of the weld is large (6.71 μm). The carbide particle size between the dendrites is coarse, and the solidification microsegregation of Mo, Cr alloy elements is serious. The width of heat affected zone is about 0.29 mm. The eutectic structure of γ+carbide is formed in the grain boundary and grain interior. This is because during the heating process of the welding, the spherical carbide particles and the surrounding austenite in the heat-affected zone liquefy and the eutectic structure is formed during the solidification process after welding. The front width of the laser weld obtained by low heat input (90 J/mm) process parameters is 2.28 mm, the grains inside the weld are columnar which is formed by epitaxial growth along the fusion line and directional solidification along the heat flow direction. The secondary dendrite arm spacing in the middle of the weld is small (2.26 μm), the carbide particles between dendrites are small, and the width of heat affected zone is about 0.15 mm. The tensile strength test at room temperature (25℃) shows that the welded joints obtained under high heat input fracture from the middle of the weld, and the tensile strength and elongation decrease, which is caused by the segregation of solid solution elements in the weld. The welded joints obtained under low heat input fracture from the base metal. At high temperature (900℃), all samples fracture from the base metal, which is due to the weakening of the grain boundary of the base metal at high temperatures.
ZHU H S , NIE Y H , ZHAO S , et al. Microstructure evolution and prediction of alloy 617 during hot deformation based on dynamic recrystallization[J]. Journal of Materials Engineering, 2018, 46 (6): 80- 87.
2
REN W J , LU F G , NIE P L , et al. Effects of the long-time thermal exposure on the microstructure and mechanical properties of laser weldings of Inconel 617[J]. Journal of Materials Processing Technology, 2017, 247, 296- 305.
doi: 10.1016/j.jmatprotec.2017.05.003
WANG Y , XU F H , ZENG L , et al. Hot deformation and creep rupture behaviors of 617B nickel-base superalloy for 700 ℃(A-USC) boilers[J]. Journal of Materials Engineering, 2018, 46 (7): 100- 105.
YAO C G , LV H J , JIA X C , et al. Development of metallic thermal protection system[J]. Aerospace Materials & Technology, 2005, (2): 10- 13.
doi: 10.3969/j.issn.1007-2330.2005.02.003
5
KATAYAMA S. Fundamentals and features of laser welding[M]//Fundamentals and details of laser welding. Singapore: Springer, 2020: 35-55.
6
CHENG H , KANG L , PANG J C , et al. Effect of the welding position on weld quality when laser welding Inconel 617 Ni-based superalloy[J]. Optics & Laser Technology, 2021, 139, 106962.
SUN W J , WANG S L , TAN G H , et al. Effect of material states on microstructure and properties of GH4169 superalloy laser-welded joint[J]. Chinese Journal of Lasers, 2020, 47 (10): 75- 84.
AO S S , LUO Z , SHAN P , et al. Microstructure of Inconel 601 nickel-based superalloy laser welded joint[J]. The Chinese Journal of Nonferrous Metals, 2015, 25 (8): 2099- 2107.
WANG X G , LIU F C , ZHOU B S . Microstructure and deformation uniformity of GH3044 alloy joints by laser beam welding[J]. The Chinese Journal of Nonferrous Metals, 2019, 29 (11): 2549- 2560.
10
YU K , JIANG Z G , LI C W , et al. Microstructure and mechanical properties of fiber laser welded GH3535 superalloy[J]. Journal of Materials Science & Technology, 2017, 33 (11): 1289- 1299.
11
SONAR T , BALASUBRAMANIAN V , MALARVIZHI S , et al. An overview on welding of Inconel 718 alloy—effect of welding processes on microstructural evolution and mechanical properties of joints[J]. Materials Characterization, 2021, 174, 110997.
12
ODABAŞI A , VNLV N , GÖLLER G , et al. A study on laser beam welding (LBW) technique: effect of heat input on the microstructural evolution of superalloy Inconel 718[J]. Metallurgical and Materials Transactions A, 2010, 41 (9): 2357- 2365.
13
SHARMA S K , BISWAS K , NATH A K , et al. Microstructural change during laser welding of Inconel 718[J]. Optik, 2020, 218, 165029.
14
LI S L , LI K J , CAI Z P , et al. Behavior of M23C6 phase in Inconel 617B superalloy during welding[J]. Journal of Materials Proces-sing Technology, 2018, 258, 38- 46.
15
ZHU Z W , MA X Q , JIANG P , et al. Planar-cellular-dendritic transformation in the fusion zone of a GH909 superalloy weldment[J]. Journal of Materials Research and Technology, 2021, 10, 960- 975.
16
REN W J , LU F G , YANG R J , et al. A comparative study on fiber laser and CO2 laser welding of Inconel 617[J]. Materials & Design, 2015, 76, 207- 214.
17
LIU W , LU F G , YANG R J , et al. Gleeble simulation of the HAZ in Inconel 617 welding[J]. Journal of Materials Processing Technology, 2015, 225, 221- 228.
18
REN W J , LU F G , YANG R J , et al. Liquation cracking in fiber laser welded joints of Inconel 617[J]. Journal of Materials Processing Technology, 2015, 226, 214- 220.
2023, Vol. 51 
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