Fracture reason of 60Si2Mn steel spring

The release spring of a unit brake cylinder broke during the maintenance and test. The fracture reason of the spring was analyzed by means of macroscopic observation, chemical composition analysis, hardness test, metallographic examination and scanning electron microscope analysis. The results show that the spring gradually formed a flat crack source region under the interaction of stress and hydrogen after loading, and the crack expanded rapidly, and finally brittle fracture occurred.