440C steel is a martensitic stainless steel. It contains 1.0% carbon and 16-18% chromium. It has strong rust resistance and is a high-quality stainless steel.

It is mainly used for manufacturing bearing components that operate in corrosive environments and strong oxidizing atmospheres without lubrication. 440C has good high-temperature dimensional stability, so it can also be used as corrosion-resistant high-temperature bearing steel. Additionally, it can be used to produce high-quality cutting tools, such as medical scalpels, scissors, nozzles, bearings, etc. 440C has a relatively low capacity to withstand dynamic loads. 

 

Chemical Composition

 

Carbon C: 1.00

Chromium Cr: 17.50

Cobalt Co: -

Nitrogen N: -

Manganese Mn: 0.50

Molybdenum Mo: 0.50

Nickel Ni: -

Phosphorus P: 0.04

Silicon Si: 0.30

Sulfur S: 0.03

Tungsten W: -

Vanadium V: -

Mechanical Properties

Hardness: Annealed, ≤269HB;

Quenched and Tempered, ≥58HRC

Mechanical Properties:

Internal Stress (250 N/mm2)

Tensile Strength (560 N/mm2)

EL (18%) HB (250) [1] 

Heat Treatment Process

1) Annealing, 800～920℃ slow cooling;

2) Quenching, 1010～1070℃ oil cooling;

3) Tempering, 100～180℃ rapid cooling. [1] 

Application Range

Mainly used for manufacturing bearing components that operate in corrosive environments and strong oxidizing atmospheres without lubrication. 440C has good high-temperature dimensional stability, so it can also be used as corrosion-resistant high-temperature bearing steel. Additionally, it can be used to produce high-quality cutting tools, such as medical scalpels, scissors, nozzles, bearings, etc. 440F: A steel grade that improves the machinability of 440C steel, used for automatic lathes. Like ordinary alloy steels, it has the characteristic of hardening through quenching, so a wide range of different mechanical properties can be obtained by selecting the grade and heat treatment conditions. 440C has a relatively low capacity to withstand dynamic loads. [1] 

Delivery Condition

Generally delivered in heat-treated condition, with the type of heat treatment specified in the contract; if not specified, it is delivered in non-heat-treated condition.

Characteristics

440: High-strength tool steel, with slightly higher carbon content. After appropriate heat treatment, it can achieve high yield strength, with hardness reaching up to 58HRC, making it one of the hardest stainless steels. The most common application example is "razor blades." There are three commonly used models: 440A, 440B, 440C, and also 440F (easy-to-machine type).