Stress corrosion test

Stress corrosion refers to the damage caused by metal in corrosive medium under tensile stress. This kind of corrosion generally passes through grains, which is called transgranular corrosion. The process of material failure caused by the combination of strain and corrosion caused by residual or applied stress. The fracture of materials caused by stress corrosion is called stress corrosion fracture.            Generally speaking, there are two kinds of stress corrosion: anodic dissolution and hydrogen induced cracking. The common mechanism of stress corrosion is: under the action of stress and corrosion medium, the oxide film on the surface of parts or components is damaged by corrosion, the damaged surface and the undamaged surface form anode and cathode respectively, the metal at anode becomes ion and is dissolved, resulting in current flowing to cathode. Because the area of anode is much smaller than that of cathode, the current density of anode is very large, which further corrodes the damaged surface. Under the action of tensile stress, cracks gradually form at the failure site, and the cracks gradually expand with time until fracture. This kind of crack can not only develop along the grain boundary, but also develop through the grain.