Improvement on the Fatigue Performance of 2024-T4 Alloy by Synergistic Coating Technology

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.

Synergistic effect of environmental media and stress on the fatigue fracture behaviour of aluminium alloys

“…There have been growing interests in light metals, such as aluminium, magnesium and titanium-aluminium alloys, which have been widely applied to aeronautic and automotive industries because of their high strength-toweight ratios, [1][2][3] but improvements are needed in their fatigue properties, [4][5][6][7][8] very high-cycle fatigue behaviour of aluminium alloys [9][10][11] and some factors of high humidity on fatigue properties of aluminium alloys. 12 As one of the important materials in aeronautic and automotive structures, the aluminium alloy is usually directly exposed to the corrosive environment with stress/strain, 13 in which the corrosive fatigue cracking mechanism is rather a complex process and needs to be deeply understood.…”

High-Cycle Microscopic Severe Corrosion Fatigue Behavior and Life Prediction of 25CrMo Steel Used in Railway Axles

“…The sample for the rotating bending fatigue tests in the environmental media shown in Figure 1 was designed with a circular center notch to control the stress concentration factor. The radius of the notch is 7 mm, and the minimum diameter is 4 mm [25][26][27]. All environmental fatigue test samples were machined from the surface layer of the railway axle by turning and grinding to the required dimensions and then abraded using abrasive paper to achieve a surface roughness of approximately R a = 0.6 to 0.8 µm prior to the environmental fatigue testing.…”

High-Cycle Microscopic Corrosion Fatigue Behavior and Life Prediction of 25CrMo Steel Used in Railway Axle

“…The radius of the notch is 7 mm, and the minimum diameter is 4 mm [22][23][24]. All environmental fatigue test samples were machined from the surface layer of the railway axle by turning and grinding to the required dimensions and then abraded using abrasive paper to achieve a surface roughness of approximately Ra =0.6 to 0.8 μm prior to the environmental fatigue testing.…”