Evaluation of interaction between Sn and passivated stainless steel through an easy chromaticity approach

The interaction between Sn and passivated stainless steel was evaluated through an easy chromaticity approach. The microstructure of Fe–Sn intermetallics (IMCs) was observed, and their growth was inspected at different time after the interaction. The oxide film on stainless steel exposed in air locally delayed IMC growth, and the chemically passivated film protected stainless steel from Fe–Sn compound formation. To investigate the interaction mechanism, the integrity of passivated films grown on stainless steel was evaluated by chromogenic inspection. The interaction extent was related to colour measurement a*. Results indicated that the measured value of a* from the inspection decreased with the increasing exposure time, and a minimum a* value was found in chemically passivated samples. The tendency of the colour measurement was consistent with the effect of passive film on IMC growth. The interfacial reaction of passivated stainless steel with Sn was illustrated based on the integrity of the passive films.