Enhancing Ultra-High Cycle Fatigue Properties of GH4169 Alloy Using Microscale Laser Shock Peening

Daihua Li; Weifeng He; Xiangfan Nie; Yuhang Wu; Jile Pan

doi:10.3788/CJL250513

Chinese Journal of Lasers, Volume. 52, Issue 12, 1202201(2025)

Enhancing Ultra-High Cycle Fatigue Properties of GH4169 Alloy Using Microscale Laser Shock Peening

Daihua Li¹, Weifeng He^1,2、*, Xiangfan Nie^1,2, Yuhang Wu¹, and Jile Pan²

¹National Key Lab of Aerospace Power System and Plasma Technology, School of Aviation Engineering, Air Force Engineering University, Xi’an 710038, Shaanxi , China

²National Key Lab of Aerospace Power System and Plasma Technology, Xi’an Jiaotong University, Xi’an 710038, Shaanxi , China

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Figures & Tables(17)

Fig. 1. Metallographic structure of GH4169 with EDS analysis results of phase indicated by arrow shown in inset

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Fig. 2. Schematic diagram of ultra-high cycle fatigue specimen (unit: mm)

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Fig. 3. Microscale laser shock peening treatment. (a) Microscale laser shock peening diagram; (b) microscale laser shock peening area and scanning path of microscale laser shock peening

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Fig. 4. S-N curves of different samples

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$Ultra-high cycle fatigue fracture of untreated specimen (σa=425 MPa, Nf=1.56×107). (a) General view of fatigue fracture; (b) crack growth region and crack initiation region; (c) enlarged view of crack initiation region$

Fig. 5. Ultra-high cycle fatigue fracture of untreated specimen (σ_a=425 MPa, N_f=1.56×10⁷). (a) General view of fatigue fracture; (b) crack growth region and crack initiation region; (c) enlarged view of crack initiation region

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$Ultra-high cycle fatigue fracture of 62 mJ&1 time specimen (σa=425 MPa, Nf=1.21×108). (a) General view of fatigue fracture; (b) general view of crack initiation region; (c) edge of crack initiation region; (d) enlarged view of crack initiation region$

Fig. 6. Ultra-high cycle fatigue fracture of 62 mJ&1 time specimen (σ_a=425 MPa, N_f=1.21×10⁸). (a) General view of fatigue fracture; (b) general view of crack initiation region; (c) edge of crack initiation region; (d) enlarged view of crack initiation region

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$Ultra-high cycle fatigue fracture of 62 mJ&3 times specimen (σa=425 MPa, Nf=7.88×108). (a) General view of fatigue fracture;(b) general view of crack initiation region; (c) facet morphology;(d) edge of crack initiation region with carbon element distribution in inclusion shown in inset$

Fig. 7. Ultra-high cycle fatigue fracture of 62 mJ&3 times specimen (σ_a=425 MPa, N_f=7.88×10⁸). (a) General view of fatigue fracture;(b) general view of crack initiation region; (c) facet morphology;(d) edge of crack initiation region with carbon element distribution in inclusion shown in inset

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$Ultra-high cycle fatigue fracture of 82 mJ&1 time specimen (σa=425 MPa, Nf=4.32×108). (a) General view of fatigue fracture; (b) crack initiation region; (c) facet morphology$

Fig. 8. Ultra-high cycle fatigue fracture of 82 mJ&1 time specimen (σ_a=425 MPa, N_f=4.32×10⁸). (a) General view of fatigue fracture; (b) crack initiation region; (c) facet morphology

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Fig. 9. Three-dimensional morphologies of specimens. (a) Untreated; (b) 62 mJ&1 time; (c) 62 mJ&3 times; (d) 82 mJ&1 time

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Fig. 10. Surface roughness values of specimens

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Fig. 11. Residual stress distributions of treated specimens in gradient direction

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Fig. 12. Inverse pole figures and KAM diagrams of surfaces along gradient direction. (a)(b) Untreated; (c)(d) 62 mJ&1 time; (e)(f) 62 mJ&3 times; (g)(h) 82 mJ&1 time

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Fig. 13. Grain size distributions of surface layer after microscale laser shock peening

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Table 1. Chemical compositions of GH4169 (mass fraction, %)
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Table 1. Chemical compositions of GH4169 (mass fraction, %)
Fe Ni Mo Nb Ti Al Si P Mn S Cr C
Bal. 53.8400 2.9900 5.4400 0.9900 0.5500 0.0580 0.0110 0.0620 0.0005 18.2400 0.0250

Table 2. Mechanical properties of GH4169
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Table 2. Mechanical properties of GH4169
Parameter Tensile strength /MPa Yield strength /MPa Elongation /% Shrinkage /% Elastic modulus /GPa
Value 1469 1211 17 31 191

Table 3. Process parameters of microscale laser shock peening
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Table 3. Process parameters of microscale laser shock peening
Parameter Content
Constrained layer Water
Spot diameter /mm 0.36
Power density /（GW/cm²） 6
Impact energy /mJ 62， 82
Overlap rate /% 50%
Impact number 1，3

Table 4. GND density distributions of surface layers after microscale laser shock peening under different parameters and average GND densities

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Table 4. GND density distributions of surface layers after microscale laser shock peening under different parameters and average GND densities

GND density	Frequency /%
GND density	Untreated specimen	62 mJ&1 time specimen	62 mJ&3 times specimen	82 mJ&1 time specimen
Average GND density	0.75×10¹⁴/m²	0.78×10¹⁴/m²	0.90×10¹⁴/m²	0.85×10¹⁴/m²
0×10¹⁴/m²≤ρ_GND≤2×10¹⁴/m²	95.91115	98.02173	98.04058	98.03120
2×10¹⁴/m²<ρ_GND≤4×10¹⁴/m²	3.33221	1.67276	1.73669	1.70007
4×10¹⁴/m²<ρ_GND≤6×10¹⁴/m²	0.55848	0.25572	0.16889	0.22700
6×10¹⁴/m²<ρ_GND≤8×10¹⁴/m²	0.14348	0.04080	0.03525	0.03179
8×10¹⁴/m²<ρ_GND≤10×10¹⁴/m²	0.03957	0.00514	0.01506	0.00674
10×10¹⁴/m²<ρ_GND≤12×10¹⁴/m²	0.01126	0.00225	0.00256	0.00225
12×10¹⁴/m²<ρ_GND≤14×10¹⁴/m²	0.00386	0.00161	0.00096	0.00096

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Daihua Li, Weifeng He, Xiangfan Nie, Yuhang Wu, Jile Pan. Enhancing Ultra-High Cycle Fatigue Properties of GH4169 Alloy Using Microscale Laser Shock Peening[J]. Chinese Journal of Lasers, 2025, 52(12): 1202201

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