440A stainless steel is a martensitic stainless steel that is known for its high chromium content, which gives it excellent corrosion resistance in harsh environments. It is often used in the manufacture of bearing parts that are exposed to corrosive environments and do not require lubrication.

In addition to its excellent corrosion resistance and hardness, 440A stainless steel also has good high-temperature dimensional stability. This means that it can maintain its shape and size even when exposed to high temperatures, which makes it suitable for use in high-temperature applications such as furnace parts and cutting tools.