Like many metals in marine applications, metal 400 works nicely in lowing salt water. Stagnant salt water may cause pitting corrosion.
The most frequent bellows material, series 300 stainless steel, can be more prone to stress corrosion cracking and salt water is filled with chlorides. The material is also useful in other corrosive applications like hydrofluoric, hydrochloric, and sulfuric environments. As with any material choice, a metallurgist should suggest the bellows material for use for a given program.
Alloy 400 also holds up well in sub-zero temperatures similar to stainless steel. When it comes to marine engine applications the majority of the bellows continue to be stainless steel. This is most likely because stainless steel works better in the higher engine temperatures in addition to having superior fatigue resistance that’s necessary for engine vibration.