440C stainless steel is metallogenic structure belongs to martensitic steel, the production process requirements are higher, domestic can produce stainless steel 440C enterprises are relatively few, so can produce 440C material enterprises are often known as special stainless steel reputation. Heat treatment process is more complex, easy to crack, and high precision requirements, is the steel ball in the hard stainless steel ball: HRC≧58. The hardness is close to the bearing steel ball, but it has more anti-rust and anti-corrosion properties than the former. Compared with 440 stainless steel ball has more anti-rust, anti-corrosion properties, hardness, wear resistance is also improved. Mainly used for manufacturing bearing parts in corrosive environment and strong oxidation atmosphere without lubrication. 440C has good high temperature size temperature property, so it can also be used as corrosion resistant high temperature bearing steel.