Titanium alloy stress corrosion cracking

Stress corrosion cracking (SCC) of titanium alloys was once one of the very active research topics at home and abroad, especially in the aerospace field. Industrial practice shows that most of the titanium welding wire used in the chemical industry are very resistant to stress corrosion. For cracking, stress corrosion cracking may occur only in some special media, such as pure methanol, fuming nitric acid, halide aqueous solution of nitrogen tetroxide, and liquid metal calcium and mercury. Industrial practice has proved that the actual occurrence of stress corrosion cracking accidents is much less than the stress corrosion sensitivity found in the laboratory.

The stress corrosion susceptibility is related to factors such as medium composition, pH value, potential, temperature, and even the viscosity of the medium. The addition of halogen ions improves the stress corrosion sensitivity and increases with the increase of ion concentration. Increased temperature and decreased viscosity can accelerate the rate of cracking.

The mechanism of stress corrosion cracking is still not completely unified. At present, there are two main types of viewpoints: stress-accelerated anodic dissolution and hydrogen enrichment at the crack tip. In fact, this may not necessarily be a tit-for-tat irreconcilable viewpoint. condition. However, a lot of practice shows that hydrogen-induced cracking is a very important cause of stress corrosion cracking, especially the SCC cracking phenomenon found in general industries (such as chemical industry).