Analysis on Fracture Reason of High Strength Bolt Made by 40ACR Steel

The high strength friction grip bolt made by 40ACR steel broke in use.Through a series of testing methods including chemical composition analysis, metallographic examination, hardness testing, fracture analysis and so on, the fracture reason was analyzed.The results showed that the thick decarburized layer led to reduce the mechanical property was the main reason, the unreasonable installation of electric engine led to the low cycle fatigue was the other reason.