440C Stainless Steel Plate - UNS S44004

Type 440C (UNS S44004) is a martensitic stainless steel with high carbon and chromium content.  Molybdenum improves the steel deep hardening and toughness.  It also enhances wear resistance. After heat treatment, it is capable of attaining the highest strength, hardness and wear resistance of all stainless alloys. 

440C stainless steel derives its corrosion resistance from the inclusion of chromium, and is comparable to grade 304. Highest resistance can be achieved through hardening and polishing, and the properties of 440C steel make it ideal for knives and cutting instruments like surgical blades. It maintains good corrosion resistance to fresh water, foods, and mild acids. Once hardened, this material holds a sharp edge and resists corrosion, and it can be polished to a near mirror finish.  Its toughness and ability to resist wear makes 440C stainless steel a good choice for tools like chisels and ball bearings.  We sell 440C stainless steel plate products in various thicknesses. Please contact us if you have any questions about our inventory or processing and cutting services for this material.

Working with 440C stainless

This grade of stainless steel plate can be hardened through heat treatment, but machining is preferable in the annealed condition and becomes extremely difficult once hardened.  Recommend carbide or ceramic tooling, and chips are tough and stringy, requiring chip breakers to improve chip control and reduce cutting resistance.  440C is not usually welded due to its tendency to air harden, resulting in cracking - if welding is required, pre-heat to 250°C and follow with a post weld annealing and slow furnace cooling to prevent cracking.