440 stainless steel, sometimes referred to as razor blade steel, is one of the most popular and widely used varieties of the corrosion-resistant stainless steels. It has a high hardness and good edge retention and is easy to cut. It also has superior strength and toughness compared to austenitic types of the steel family. It is a martensitic steel with carbon and chromium content, which helps it resist corrosion. It can also be hardened to a high level through heat treatment, making it ideal for use in blades and tools like knives and surgical instruments.
Unlike austenitic grades, which can only be cold worked, 440 is also slightly cold workable. However, it is a tough material that requires patience and care when working with it. It is important to follow the machine manufacturer’s recommendations for tool type, feeds and speeds when machining. It machines well in the annealed condition, but it is recommended to use chip curlers and breakers as chips are tough and stringy.
While 440 steel does not respond well to oxidation, it is still resistant to fresh water and some mild acids. This makes it a great choice for food processing and marine applications, as well as tools that will be used in saltwater environments. Its ability to hold a sharp edge and withstand heavy use also makes it an excellent choice for knives, as it is less likely to dull or rust than other varieties of the stainless steels.