Susceptibility of 316L stainless steel to crevice corrosion in submersible solenoid valve

The susceptibility of 316L stainless steel to crevice corrosion was investigated by using immersion test and electrochemical test. Three kinds of crevices including 316L‐to‐polytetrafluoroethylene (PTFE) crevice, 316L‐to‐fluoroelastomeric (FKM) crevice and 316L‐to‐316L crevice were tested in artificial seawater at 50°C. The results indicate that 316L stainless steel specimen is the most susceptible to crevice corrosion when it is coupled to 316L stainless steel crevice former, while it is the least susceptible when it is coupled to FKM crevice former. It suggests that during submersible solenoid valve design, the crevice of metal‐to‐metal should be moderately large so that crevice corrosion can not initiate and propagate, and FKM O‐ring rather than PTFE O‐ring should be selected as obturating ring. The corroded surface morphology was investigated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Three regions including passive region, active region and variable region can be observed on crevice corrosion sites.