What are the materials of stainless steel? It can be divided into Cr series (400 series), zhiCr-Ni series (300 series), daoCr-Mn-Ni (200 series), heat-resistant chromium alloy steel (500 series) and precipitation hardening series (600 series). Stainless steel is often divided into martensitic steel, ferritic steel, austenitic steel, austenitic-ferritic (duplex) stainless steel and precipitation hardening stainless steel according to the state of organization. In addition, it can be divided into: chromium stainless steel, chromium nickel stainless steel and chromium manganese nitrogen stainless steel.