Abstract
In this paper, rotating bending fatigue tests of 2024-T4 Al alloy with different oxide coatings were carried out. Compared to the uncoated and previously reported oxide coatings of aluminum alloys, the fatigue strength is able to be enhanced by using a novel oxide coating with sealing pore technology. These results indicate that the better the coating surface quality is, the more excellent the fatigue performance under rotating bending fatigue loading is. The improvement on the fatigue performance is mainly because the fatigue crack initiation and the early stage of fatigue crack growth at the coating layer can be delayed after PEO coating with pore sealing. Therefore, it is a so-called synergistic coating technology for various uses, including welding thermal cracks and filling micro-pores. The effects of different oxide coatings on surface hardness, compressive residual stress, morphology and fatigue fracture morphology are discussed. A critical compressive residual stress of about 95–100 MPa is proposed.
Highlights
The light alloys, such as aluminum and magnesium alloys, have been widely used in the automotive and aeronautic industries, due to their low density and high strength-to-weight ratio
The S-N curves indicated that the fatigue strength of both hard anodized coated aluminum and plasma electrolytic oxidation (PEO) coated aluminum is lower than that of uncoated aluminum alloy
The effect of the coating formed by the PEO process slightly reduces the fatigue strength of the aluminum substrates, but the decrease in the fatigue strength of the PEO coating was much lower than that of the hard anodized coating, the fatigue strength of the PEO coating is still smaller compared with the uncoated aluminum alloy
Summary
The light alloys, such as aluminum and magnesium alloys, have been widely used in the automotive and aeronautic industries, due to their low density and high strength-to-weight ratio. In these fields, the general comprehensive requirements for the components include the high fatigue strength, good wear resistance and better corrosion resistance. The second requirement for the light alloys is achieved by using ceramic coating technologies with a high wear resistance [4,5]. The third requirement for light alloys is usually achieved by the selection of various coatings to avoid the corrosion of the substrate. A hard anodized ceramic coating led to about a 75%
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