Corrosive environmental media is often the main cause of spring failure. Under the action of stress, many metals are more susceptible to corrosion by corrosive environmental media. Therefore, springs are extremely sensitive to stress corrosion due to high elasticity, and springs are often subjected to cyclic loading, so springs are also prone to fatigue fracture in corrosive media. In order to prevent the harmful effects of environmental media, surface protection coatings are often used. Electroplated layers of certain metals or coatings of organic coatings such as paints are the most commonly used protective layers. This type of protection is very effective, but these protective layers are easily peeled off, especially the coil springs of the dense bouncing ring. The protective layer between the first to the second ring wears or ruptures, and this is the easiest place. The place where the failure occurred. = Example 3> Corrosion fatigue failure of high speed diesel engine valve springs. Original situation: A high-speed diesel engine valve 50CrVA steel is manufactured. It requires hardness of HRC45-50 after quenching and tempering, and it is treated with blue and shot peening. After 500 hours of rupture, most of them broke at one end, and a few of them broke. Whether the valve spring or the valve spring is broken in the same part, that is, the fracture is in the circle of the first circle and the second circle. Observation and analysis: the fracture is at an angle of 45b to the spring wire shaft. The naked eye has obvious fatigue source zone, fatigue expansion zone and final fracture zone. The metallographic structure near the fracture is tempered martensite, no surface decarburization is found. Other abnormal organizations. The hardness of the spring is HRC47-49, which meets the requirements of the drawings. Fracture scanning electron microscopy showed that the fracture of the sugar-like block along the strip-shaped fracture features in the fatigue source region, indicating that fatigue and corrosion occur simultaneously in the formation of the fatigue expansion zone. Scanning electron microscopic observation was carried out on the surfaces of the first and second laps, and the pits on the etch pit and the shot peening surface were found, and there were friction marks and etch pits at the contact plane. Conclusion: The valve spring is broken due to corrosion. 4. Improvements: Eliminate surface defects and use a suitable coating. Decorative Ceiling Fan,luxury ceiling fan,inverter ceiling fan,ceiling fan modern JIANGMEN ESCLIGHTING TECHNOLOGY LIMITED , https://www.jmesclightingfan.com
Failure of spring caused by environmental medium
Corrosive environmental media is often the main cause of spring failure. Under the action of stress, many metals are more susceptible to corrosion by corrosive environmental media. Therefore, springs are extremely sensitive to stress corrosion due to high elasticity, and springs are often subjected to cyclic loading, so springs are also prone to fatigue in corrosive media.