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Considering the previous background on the heat transfer tubes of nuclear industry steam generators, the mechanism of stress corrosion crack initiation in the scratched areas is the most complex among all locations, being far more complex than that in the other typical areas. Comparison of mechanism complexity at various locations: The scratched area involves multiple factors such as the material’s microstructure, electrochemistry, stress, and the environment, all of which are interconnected. It involves the combined action of multiple mechanisms such as highly active dissolution in the nanocrystalline structure, pitting-induced effects, preferential cracking at deformed grain boundaries, and hydrogen embrittlement; as a result, the crack initiation paths for scratches at different depths differ significantly, with numerous mechanism variables and complex coupling relationships. In the gap area of the tube support plate, the key factor is the combined effect of the concentration of impurity ions within the gaps, battery acidification, and contact stress. The variables are concentrated in the chemical environment of interstitial water, the mechanism pathways are relatively clear, and the number of coupling dimensions is less than that in the scratched area. The expansion tube transition zone is primarily characterized by the combined effects of residual tensile stress in the expansion tube, chromium depletion at grain boundaries (in early-stage 600 alloy), and localized sediment deposition. The stress source is single, the growth mechanism is primarily grain-boundary anodic dissolution, and the variability is highly controllable. The core of the U-shaped elbow section lies in the simple coupling between the residual bending stress and the high-temperature chlorinated water environment on the secondary side. The physiological pathway for germination is clear; by simply controlling residual stress and water quality, the germination probability can be significantly reduced, resulting in the lowest level of complexity. The germination mechanism in the scratched area requires taking into account more than a dozen interrelated variables, such as the depth of the scratch, the microstructure of the deformed layer, local electrochemical potential differences, impurity ion concentrations, and residual strain distribution. It is a complex mechanism scenario for which there is still much research to be done in this field.