How to choose stainless steel compounds in different place. Like other steels, they are iron and carbon alloys to which chromium and other elements are added to improve strength. Stainless steel is a simple term for an indestructible material that does not rust and withstands all forms of corrosion. This protective layer significantly slows down the oxidation process (formation of rust), which is not the case with a non-alloyed material that can rust or corrode because its oxide layer is porous.
A stainless steel grade corresponds to the metal's chemical composition, not its surface appearance. Grades are selected depending on the environment and atmospheric conditions. Austenitic steels have high hot or cold corrosion resistance in aggressive environments. This resistance is due to chromium (over 15%) which protects the surface of the alloy by passivation.
Resistance to atmospheric corrosion has then multiplied a hundredfold compared to standard steels. A2 (AISI 304) and A4 (AISI 316) are the most widely used grades. The high-strength stainless steel grades A2-70 and A4-80 have become a reference standard. There is no visible difference between A2 and A4 stainless steel. However, they have slightly different characteristics.
SS 316 Fasteners are mainly used in the chemical and food industry, while A4 stainless steel, also known as marine grade stainless steel, is widely used in shipbuilding due to its excellent salt spray resistance. A2 stainless steel comprises 18% chromium and 8% nickel, while A4 stainless steel comprises the same amount of chromium and nickel plus 3% molybdenum. Plus, A4 stainless steel makes fasteners easy to make, clean, polish, and weld.