A2 stainless steels:

A2 stainless steels steels are the most widely used stainless steels. They are used for kitchen equipment, appliances for the chemical industry, fastening
 fasteners. Suitable for freshwater applications, but A4 or 316 stainless steels are preferable.

The molybdenum-alloyed A4 steels are "acid-proof" and provide better corrosion resistance. A4 is widely used in industry and should be preferred in the marine sector.