抄録
Using a SERT (slow extention rats technique) method, stress corrosion cracking (SCC) behaviors of Type 304 stainless steel rods with the 0.2R round notch were investigated in 42% MgCl2 aqueous solution in the range of crosshead speed (CS) from 4×10-5mm/min to 4mm/min. The effects of potential, temperature and alloying elements on SCC were studied by this method. Constant load tests were also carried out in the solution. After the tests the fracture mode was examined by a scanning electron microscope. In the solution at 143°C the maximum susceptibility to SCC was observed at the CS of 2×10-4mm/min under the corrosion potential. CS at the maximum susceptibility shifted to the lower value of 1×10-4mm/min at anodic potential and to the higher value of 8×10-4mm/min at cathodic potential. In the solution at 100°C the effect of potential on SCC susceptibility was the same as that in the solution at 143°C. With increasing susceptibility to SCC increased the ratio of transgranular cracking in a fracture surface. Alloying elements such as Mo and Cu increased susceptibility to SCC. Mechanism of SCC in 42% MgCl2 in SERT method was discussed from the view point of the formation rate of slip steps and their characteristics of dissolution-repassivation.
