Contact-mode high-speed atomic force microscopy (HS-AFM) was used to measure in situ stress corrosion cracking (SCC) at the nanometer scale on AISI Type 304 stainless steel in a concentrated sodium thiosulfate solution. Prior to in situ experiments, the roles of microstructure, environment, and stress in SCC were independently studied. Grain boundary uplift was observed before cracking, suggesting a subsurface contribution. FIB milling revealed a network of intergranular cracks below the surface, lined with a thin oxide. APT analysis showed a layered oxide composition at the crack walls. The study demonstrates how in situ HS-AFM combined with other techniques provides insights into SCC mechanisms.

S. Moore, R. Burrows, D. Kumar, M. B. Kloucek, A. D. Warren, P. E. J. Flewitt, L. Picco, O. D. Payton, T. L. Martin