The client experienced premature failure of a stainless steel gasoline tank during salt spray testing.
Planar and cross-sectional SEM/EDS were performed to determine the composition of the tank material. No unusual compounds or contaminants were found. Using planar SEM, a network of microcracks covering the metal surface was discovered. Cross-sectional SEM analysis indicated that corrosion cracks penetrated from the surface microcracks to the deeper layers of the material.
The surface microcracks were serving as preferential sites for corrosion initiation and propagation. Corrosion that initiated at the gasoline tank surface propagated into deep steel layers creating cracks, some of which were parallel to the surface and some of which were branched.
Benefits to Customer:
Knowing the root cause of the premature failure, the client was able to focus on the cause of the microcracks.