The macroscopic fatigue defects of rolling fatigue wear are mainly formed by the propagation of fatigue microcracks. Fatigue micro cracks often appear on the surface or sub surface of gray cast iron. In order to ensure that laser surface treatment can effectively improve the fatigue wear resistance of gray cast iron, it is generally required that the depth of surface treatment is greater than the maximum depth of theoretical cracks. Through a large number of report analysis, theoretical calculation and numerical simulation analysis, the possible location of fatigue defects is determined, which provides a theoretical basis for the feasibility of laser bionic treatment.
Through theoretical calculation, the maximum possible depth of fatigue microcracks in gray cast iron is 12.7 μm. It is far less than the minimum depth of the prepared bionic unit, indicating that the unit can effectively play a strengthening role.
The strengthened layer prepared by laser treatment can be well combined with the matrix, and the existing phase transformation zone can effectively reduce the hardness gradient between the strengthened layer and the matrix.
A large amount of residual compressive stress exists on both sides of the element body, which can well hinder the crack propagation of gray cast iron and the interconnection of cracks in different areas, and effectively reduce the size of fatigue spalling pit of gray cast iron.