Salt air, chloride ions and water-treatment chemicals attack carbon steel fan blades. Stainless steel removes the corrosion pathway, but grade selection matters.
201 vs 304
201 is suitable for mild corrosivity. 304 contains more nickel and generally offers more margin in higher-chloride or chemical environments. Neither grade is immune to every water chemistry.
We confirm the grade against chloride concentration, pH, temperature and cleaning practice. For high-chloride or high-temperature duties, the water chemistry should be reviewed before the fan is specified.