It has 0.75 to 0.95 percent carbon. 440C:this is also a hardenable stainless steel alloy, hardenable to a higher hardness than 440B. It has good corrosion resistance, and is used in ball bearing balls and races, high pressure nozzles, valve seats and high wear components. It has 0.95 to 1.20 percent carbon.Alloy 440C/ AISI 440C / AMS 5630 - Aircraft Materials1.0 max. 0.015 S max. 16.0/ 18.0. 0.8 max. -. -. AISI 400C is a high carbon chromium steel is designed to provide stainless steel properties with maximum hardness. After heat-treatment Type 440C attains the highest hardness of any stainless steel (about 60 HRC). This stainless steel is principally used for bearing assemblies including ball bearings and should be considered for needle valves and ball check valves.