440C Round Bar steel is characterized by good corrosion resistance in mild domestic and industrial environments, including fresh water, organic materials, mild acids, various petroleum products, coupled with extreme high strength, hardness and wear resistance when in the hardened and tempered condition. Grade 440C stainless steel is capable of attaining, after heat treatment, the highest strength, hardness and wear resistance of all the stainless alloys. Small AISI 440C steel sections can be air cooled and quite large sections oil quenched for maximum through hardness.
As heat treated, the 440 steel series are difficult to machine because of their high hardness. For parts that require extensive machining, the free-machining versions, Type 440F or Type 440F Se, offer improved machining properties.