440C steel is a martensitic stainless steel. It is highly rust-resistant and a high-strength cutting tool steel. It has a slightly higher carbon content and, after proper heat treatment, can achieve a higher yield strength. Its hardness can reach 58HRC, making it one of the hardest stainless steels. There are three common grades: 440A, 440B, and 440F (for easy machining).

Applications: Primarily used for manufacturing bearing components operating in corrosive environments and non-lubricated, highly oxidizing atmospheres. 440C has excellent high-temperature dimensional stability, making it suitable for use as a corrosion-resistant, high-temperature bearing steel. It can also be used to manufacture high-quality cutting tools, such as medical scalpels, nozzles, and bearings.