Effect of Modification of the Surface of VNS-5 Steel Samples by Ion-Plasma Methods on the Fracture Pattern during Fatigue Tests

Samples of structural aviation steel VNS-5 were implanted with carbon ions using ion-beam implantation. The modified layer was about 200 nm; the carbon content did not exceed 10% in this layer. This study shows that the VNS-5 specimens implanted with carbon ions exhibit high low-cycle fatigue properties. The origin and behavior of fatigue cracks in implanted samples differs from non-implanted material and does not depend on the magnitude of the load at low-cycle fatigue. The high surface residual compressive stress in the implanted material helps to suppress the nucleation and spread of surface cracks, thereby improving the fatigue resistance of steel.