Abstract: The effect of applied potential on corrosion cracking of 40CrNi2Si2MoVA steel in 3.5% NaCl solution is investigated by using computer assited electrochemical measuring technique, slow strain rate tension and fracture mechanics methods. It has been found that the susceptibility to corrosion cracking of 40CrNi2Si2MoVA steel increases with applied potential. The total elongation to fracture εf of the steel, at-635m V and-1 350mV, is decreased to 54% and 49% of that in air respectively. The (da/ dt) II of the steel increases at anodic polarization (coupling Cu) and decreases at cathodic polarization. According to the variation of corrosion cracking feature in different conditions and SEM fractographic analysis, it is suggested that the corrosion cracking of 40CrNi2Si2MoVA steel should result from the combined action of local anodic dissolution at the crack tip and hydrogen embrittlement.

Key words: negative anodic polarization, 40CrNi2Si2MoVA, corrosion cracking characteris