Improvement of fatigue wear resistance of gray cast iron by Laser Biomimetic treatment

Fatigue wear failure of gray cast iron is a phenomenon that metal is removed from the contact area under the action of cyclic shear stress and normal stress. It is known from previous studies that the removal of metal sheet is related to crack propagation and the strength of the material in the contact area (crushing or adhesion). By analyzing the wear surface of different areas, the mechanism of improving the fatigue wear resistance of bionic treated gray cast iron was discussed. In addition, the contact stress distribution on the surface of the material is further systematically understood through the finite element analysis method, so as to better explain the fatigue wear mechanism of gray cast iron.

The bionic treatment method is used to improve the fatigue wear resistance of gray cast iron surface by combining the advantages of different regions and two materials. The anti fatigue wear mechanism is discussed from the different formation modes of fatigue defects:

  1. The existence of element body can effectively reduce the tangential and axial strain accumulation and reduce the possibility of fatigue failure of gray cast iron.
  2. Fatigue microcracks of gray cast iron preferentially appear at the graphite tip, and macro cracks are formed by connecting adjacent graphite sheets; The initiation and propagation of fatigue microcracks in gray cast iron are seriously hindered by the disappearance of graphite and grain refinement.
  3. The existence of the element body bears a large amount of contact stress, reduces the stress on the substrate, and thus improves the fatigue life of the body area. Although the area of the unit body is subjected to large contact stress, the metal particle shedding caused by crushing and adhesive wear is significantly reduced.
  4. The influencing factors of fatigue wear resistance of different gray cast iron materials mainly depend on the strengthening degree of the unit body and the blocking effect on the fatigue microcrack propagation and initiation of gray cast iron.
  5. Bionic surface treatment can not only form a left-right bionic structure in the tangential direction, but also form an up-down bionic structure in the axial direction.
  6. The existence of the element body can isolate the connection of fatigue cracks in different areas, resulting in relatively small fatigue spalling. In addition, the existence of graphite can improve the fatigue wear resistance of gray cast iron.