AISI 304 stainless steel (UNS S30400) is the most commonly used material in stainless steels, and is usually purchased in an annealed or cold worked state. Because SS304 contains 18% chromium (Cr) and 8% nickel (Ni), it's also known as 18/8 stainless steel. Type 304 has good processability, weldability, corrosion resistance, heat resistance