Stress corrosion tests were conducted by using SNCM439 steel in 3.5% NaCl solution under various cathodic potentials. The crack profiles obtained in these tests were analyzed by fractal geometry. The results obtained were summarized as follows:
(1) The more base the cathodic potential is, the slower the crack growth rate becomes and the larger the branching width becomes.
(2) The profile of main cracks under cathodic polarization has the fractal character. The fractal dimension measured by the yardstick method is of no significance to the stress intensity factor and polarized electrode potential.
(3) The fractal character of stress corrosion crack branching under cathodic polarization measured by the box counting method shows the single region for the case of only micro branching, and it shows the double regions for the case of mixture of micro and macro branching.
