Investigation of stress Corrosion Cracking of the Cast and Forging Steel in Water

stress corrosion behavior of the cast and forging steel with the same heat has been investigated.Results showed that the activation energy of crack growth of the cast steel was identical with that of the forging steel and was in agreement with the apparent diffusion activation energy of hydrogen in the steel.Both cathodic and anodic polarization increased the da/dt of the cast and forging steel but the influence of the cathodic polarization was much s-tronger. Correspondingly, the steady-stat hydrogen permeation flux increased steeply with increasing the polarization current, whether cathodic or anodic polarization.
The K_ISCC of the cast steel was larger than that of the forging steel. It may be due to the fact that the steady-stat hydrogen permeation flux of the forging steel was twice as larger as that of the cast steel.The fracture modes of both cast and forging steel were clearly dependent upon K₁ at the crack tip and a transition from dimple to quasi-cleavage or intergranular was observed on the fracture surfaces with decreasing K₁.