Researches For High Temperature Corrosion Behaviors Of Cold Worded 304 Stainless Steel

Effects of dissolved oxygen(DO),Cl~-and cold work(CW)on stress corrosion cracking(SCC)susceptibility of 304 stainless steel were studied by slow strain rate,SCC and electrochemical tests in simulated primary loop water environment in PWR.Results show that:DO and Cl~-can increase SCC susceptibility and cold work can accelerate SCC growth rate.In addition,CW has little influence on electrochemical properties of oxide films while DO can increase impedances of oxide films.Fracture sections and oxide films were analyzed by Optical Microscope,Scanning Electron Microscope and Energy Dispersive Spectrometer.Obvious intergranular and transgranular crack morphologies were found.An evolutionary model on initiation,cracking and propagation of SCC was based on oxide films.During the initiation and cracking of SCC,CW,DO and Cl~-rupture films more easily and accelerate growth of crack.During the propagation of SCC,CW will act in regions at the crack tip to increase the gradient of strain in the plastic zone.The gradient of corrosion potentials will be formed due to the consumption of DO in the crack and oxide films at the crack tip will be ruptured more easily due to the concentrated Cl~-so that SCC growth rate increases.