Study on the Fatigue Resistance of Passivation Magnesium Powder Metallurgical Components for Aerospace Applications: Surface State and Stress Concentration Effect

In the aerospace field, the fatigue resistance of components is crucial and directly related to the safety and reliability of aircraft. Passivation magnesium powder metallurgical components have attracted attention due to their advantages such as lightweight and high specific strength, but the surface state and stress concentration effect have a significant impact on their fatigue resistance.

The surface condition is one of the key factors affecting the fatigue resistance of passivated magnesium powder metallurgical components. During the processing of components, various defects such as scratches, knife marks, and uneven roughness are inevitably generated on the surface. These surface defects can become the origin of fatigue cracks. A rough surface implies the presence of more microscopic protrusions and depressions. Under alternating loads, these areas will experience stress concentration, causing local stresses to be much greater than the average stress, thereby accelerating crack initiation. For example, when there are deep scratches on the surface of a component, under repeated cyclic loading, microcracks will first appear at the tip of the scratches. As the number of cycles increases, the microcracks gradually expand, ultimately leading to fatigue failure of the component.

In order to improve the surface condition and enhance fatigue resistance, surface treatment techniques are often used. Shot peening is an effective method that uses high-speed projectiles to impact the surface of a component, causing plastic deformation and forming a residual compressive stress layer. Residual compressive stress can offset some of the tensile stress caused by alternating loads, thereby suppressing the initiation and propagation of cracks. In addition, surface coating technologies such as chemical plating and electroplating can also form a uniform and dense protective film on the surface of components, which can not only improve surface roughness but also enhance surface corrosion resistance, further enhancing fatigue resistance.

The stress concentration effect also has a significant impact on the fatigue resistance of passivated magnesium powder metallurgical components. Sudden changes in the geometric shape of components, such as holes, steps, notches, etc., can lead to uneven stress distribution and stress concentration in these areas. The magnitude of the stress concentration factor depends on the characteristics of the geometric shape, such as the ratio of the diameter of the hole to the thickness of the plate, the sharpness of the notch, etc. The larger the stress concentration factor, the higher the local stress, and the greater the risk of fatigue failure of the component at that location.

In the design of aerospace components, unnecessary geometric shape changes should be avoided as much as possible, and reasonable structural forms should be adopted to reduce stress concentration. For example, for the edges of holes, rounded transitions can be used to make stress distribution more uniform. At the same time, in the manufacturing process, it is necessary to strictly control the dimensional accuracy and processing quality of the components, and reduce stress concentration caused by processing errors.

The fatigue resistance of passivated magnesium powder metallurgical components used in aerospace is significantly affected by surface conditions and stress concentration effects. By optimizing surface treatment processes and improving component structure design, its fatigue resistance can be effectively improved, ensuring the safe and reliable operation of aircraft under complex working conditions.