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Effect of laser welding on the microstructure and properties of ultrathin Inconel 718 sheets

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Jun 30, 2025

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Figure 1

Thermophysical parameters of Inconel 718: (a) specific heat, (b) density, and (c) conductivity.
Thermophysical parameters of Inconel 718: (a) specific heat, (b) density, and (c) conductivity.

Figure 2

Grid division of the finite element model.
Grid division of the finite element model.

Figure 3

Finite element model and boundary condition.
Finite element model and boundary condition.

Figure 4

Laser welding macro temperature field.
Laser welding macro temperature field.

Figure 5

(a) Transverse thermal cycle curve and (b) longitudinal thermal cycle curve.
(a) Transverse thermal cycle curve and (b) longitudinal thermal cycle curve.

Figure 6

Effect of welding parameters on tensile strength. (a) Laser power (W). (b) Welding speed (mm/s). (c) Duty cycle.
Effect of welding parameters on tensile strength. (a) Laser power (W). (b) Welding speed (mm/s). (c) Duty cycle.

Figure 7

Average tensile strength and ±2SE error bars of nine experimental groups.
Average tensile strength and ±2SE error bars of nine experimental groups.

Figure 8

Metallographic section of weld. (a) Duty cycle 50%. (b) Duty cycle 55%. (c) Duty cycle 60%.
Metallographic section of weld. (a) Duty cycle 50%. (b) Duty cycle 55%. (c) Duty cycle 60%.

Figure 9

Comparison of metallographic sections with simulation results.
Comparison of metallographic sections with simulation results.

Figure 10

Optical microscopy photo of weld morphology. (a) Duty cycle 50%. (b) Duty cycle 55%. (c) Duty cycle 60%.
Optical microscopy photo of weld morphology. (a) Duty cycle 50%. (b) Duty cycle 55%. (c) Duty cycle 60%.

Figure 11

SEM images of welds with different parameters. (a) Duty cycle 50%. (b) Duty cycle 55%. (c) Duty cycle 60%.
SEM images of welds with different parameters. (a) Duty cycle 50%. (b) Duty cycle 55%. (c) Duty cycle 60%.

Figure 12

SEM microstructures of the weld FZ: (a) Coarse and interconnected Laves particles near the fusion boundary and (b) fine and dispersed Laves particles in the weld center.
SEM microstructures of the weld FZ: (a) Coarse and interconnected Laves particles near the fusion boundary and (b) fine and dispersed Laves particles in the weld center.

Figure 13

SEM–EDS mapping of different positions of the weld seam. (a) EDS mapping of the weld top region. (b) EDS mapping of the weld middle region. (c) EDS mapping of the weld bottom region.
SEM–EDS mapping of different positions of the weld seam. (a) EDS mapping of the weld top region. (b) EDS mapping of the weld middle region. (c) EDS mapping of the weld bottom region.

Figure 14

Macroscopic location of fracture of a partially tensile specimen.
Macroscopic location of fracture of a partially tensile specimen.

Figure 15

SEM morphology of tensile specimen fracture.
SEM morphology of tensile specimen fracture.

Typical chemical composition of INCONEL 718 (mass fraction, %)_

C Si Mn Mo S Ni Cr Nb
≤0.08 ≤0.35 ≤0.35 2.8–3.3 ≤0.01 50–55 17–21 4.75–5.5

Orthogonal test analysis_

No. A. laser power (W) B. Welding speed (mm/s) C. Duty cycle (%) Tensile strength (MPa)
1 270 50 50 780
2 270 55 55 809
3 270 60 60 817
4 300 50 55 830
5 300 55 60 840
6 300 60 50 810
7 330 50 60 815
8 330 55 50 803
9 330 60 55 846
K 1 802 808 798
K 2 827 817 828
K 3 821 824 824
R 25 16 31
Priority factors C > A > B
Optimal solution 300 60 55 856

Macroscopic morphology of weld seam under different duty cycles_

No. Duty cycle (%) Front side Reverse side
a 50
b 55
c 60

Test factors and level of distribution_

Level A. Laser power (W) B. Welding speed (mm/s) C. Duty cycle (%)
1 270 50 50
2 300 55 55
3 330 60 60