Fig 1.
Dimensions of the tensile and fatigue specimens (Unit: mm).
Fig 2.
Solid solution treatment parameters of 316L.
Table 1.
Chemical composition content of 316L austenitic stainless steel.
Fig 3.
Equipment of ultrasonic impact treatment from Fig 1 in the reference [4].
Table 2.
Loading stress levels of 316L.
Table 3.
Loading stress levels of modified 316L.
Fig 4.
Metallographic structures of 316L and modified 316L specimens at different positions: (a) Matrix of the 316L specimen; (b) Matrix of the modified 316L specimen; (c) Edge of the 316L specimen; (d) Edge of the modified 316Lspecimen.
Fig 5.
Schematic diagram of the evolution of plastic deformation of modified 316L specimens.
Fig 6.
Surface texture and fine crystal organization of modified 316L specimens: (a) Surface texture; (b) Surface amorphous region; (c) Nanocrystalline region; (d) Twin delivery.
Fig 7.
SAED pattern of crystal region of modified 316L specimens.
Fig 8.
The cross-sectional hardness variation curves of with the depth.
Fig 9.
XRD peak spectra of 316 L and modified 316L specimens.
Fig 10.
Tensile test results of 316 L and modified 316L specimens: (a) Force displacement curves; (b) Tensile properties.
Fig 11.
Morphology of tensile fracture morphology of 316L specimens: (a) Full view; (b) Crack initiation site.
Fig 12.
Morphology of tensile fracture morphology of modified 316L specimens: (a) Full view; (b) Crack initiation site; (c) Middle region of fracture surface.
Table 4.
Tensile properties of 316L and modified 316L specimens.
Fig 13.
S-N curves of 316L and modified 316L specimens.
Fig 14.
S-ΔΦ curves of 316L and modified 316L specimens.
Fig 15.
SEM fracture morphology of fracture surface of 316L specimens: (a) Crack source at S = 286.66 MPa; (b) Fatigue striation at S = 286.66 MPa; (c) Crack source at S = 313.34 MPa; (d) Fatigue striation at S = 313.34 MPa.
Fig 16.
SEM fracture morphology of fracture surface of 316(UI) specimens: (a) Crack source at S = 353.34 MPa; (b) Fatigue striation at S = 353.34 MPa; (c) Crack source at S = 393.34 MPa; (d) Fatigue striation at S = 393.34 MPa.
Fig 17.
EDS analysis of crack source at S = 353.34MPa: (a) Chemical element content; (b) Chemical element distribution.
Fig 18.
Fatigue cracks on the side of the fatigue fracture surface: (a) 316L at S = 286.66 MPa; (b) Modified 316L at S = 353.34 MPa.
Fig 19.
Fatigue fracture morphology of the side of the fatigue fracture surface: (a) Away from the fracture surface of 316L; (b) Away from the fracture surface of modified 316L; (c) Near the fatigue fracture surface of 316L; (d) Near the fatigue fracture surface of modified 316L.
Fig 20.
Fatigue fracture process model: (a) 316L; (b) Modified 316L.