Corrosion fatigue is the result of corrosion and the alternating stress field interaction. Corrosion pits formed by local stress concentration, in the alternative form of fatigue crack under the action of force. At the same time, the crack expanding, but also by the corrosion medium to promote and accelerate the. The corrosion fatigue fracture often assumes the prism type, NSK bearing local intergranular corrosion zone, and the fracture surface by the serious pollution of corrosion products.
According to the mentioned above, you can see the NSK bearings corrosion fatigue has the following characteristics:
1, the surface has obvious corrosion pits, and a large number of corrosion products;
2, the fatigue crack originated in the pit;
3, the fracture is often corrosion and tarnish;
4, by using scanning electron microscopy fracture, can be seen in the transgranular fracture on mixed with local intergranular corrosion area, by means of optical microscope to check the NSK bearing can also see signs of intergranular corrosion.