Fracture Behavior of Ion-Nitrided AISI 4140 Steel in accordance with Variable Applied Current Density

Figure 4

SEM fractographs. (a) Untreated sample, 682 MPa, 291,200 cycles, air. (b) Sample A, 780 MPa, 5,523,200 cycles, air. (c) Sample B, 926 MPa, 367,700 cycles, air. (d) Sample C, 780 MPa, 1,217,500 cycles, air. (e) S-N curves of fatigue test.

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