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440 Stainless Steel

Posted by Adam Ascione on April 19, 2017

Often referred to as “razor-blade steel” due to its frequent use in the manufacture of razors and cutlery, grade 440 stainless steel provides high strength and moderate corrosion resistance. Extremely versatile, it’s used in a wide range of industries to create specialized, small-scale products and is available in various types: 440A, 440B, 440C, and 440F.

Common Applications

Besides being used for cutlery and razorblades, 440 stainless steel is also used for small applications such as dental and surgical instruments. Its high heat and corrosion resistance make it ideal for engine parts like rolling bearings and valve seats, and with superior hardness and abrasion resistance, it’s particularly well suited to manufacturing precision pivot pins and rollers.

Machinability and Formability

Through the use of heat treating and quenching, grade 440 stainless steel can be both annealed and hardened. In its annealed form, this material exhibits good machinability, but its high carbon content — and, therefore, its high hardness — can make it difficult to work with. Because its high sulfur content makes it easily machinable, type 440F is ideal for applications requiring extensive machining.

Chemical Composition

The chemical compositions of the various types of 440 stainless steel are as follows, with carbon content being the only major difference:

440A Stainless Steel

  • Chromium (Cr) — 16-18%
  • Manganese (Mn) — 1%
  • Silicon (Si) — 1%
  • Molybdenum (Mo) — 0.75%
  • Phosphorus (P) — 0.04%
  • Sulfur (S) — 0.03%
  • Carbon (C) — 0.6-0.75%

440B Stainless Steel

  • Carbon (C) — 0.75-0.95%

440C and 440F Stainless Steel

  • Carbon (C) — 0.95-1.20%

Basic Properties of 440 Stainless Steel

  • Corrosion resistance — All types of grade 440 stainless steel have a high corrosion resistance. Therefore, grade 440 is ideal for use in tempered, passivated, and hardened conditions.
  • Heat resistance — Grade 440 stainless steel has excellent heat resistance and should not be used at temperatures below a set tempering temperature; over-tempering can result in a loss of mechanical properties.
  • Heat treatability — This versatile material can be annealed at about 850-900 °C prior to slow furnace cooling at about 600 °C and air cooling. It can also be heated at 1010-1065 °C then quenched in air or oil for hardening.
  • Weldability — During welding, grade 440 stainless steel is preheated at 250 °C, followed by full annealing.
  • Machinability — 440 stainless steel can be easily machined in an annealed state.

Comparing Types of 440 Stainless Steel

When deciding on a material for your project, it’s critical to have a solid understanding of the different types 440 stainless steel and their unique benefits and features. While sharing several basic properties, as discussed above, 440 stainless steel types also differ in many ways.

Stainless Steel 440A

  • High-carbon martensitic steel
  • Moderate corrosion resistance
  • Superior ability to maintain hardness
  • Excellent wear resistance
  • Not ideal for high-temperature applications

Stainless Steel 440B

  • High-carbon martensitic steel
  • Superior ability to maintain hardness
  • Excellent machinability
  • Not ideal for welding, as it tends to air harden

Stainless Steel 440C

  • High-carbon martensitic steel
  • High strength
  • Moderate corrosion resistance (similar to that of grade 304)
  • Good wear resistance
  • Good hardness properties
  • Can attain highest strength after heat treatment compared to other stainless alloys
  • Not ideal for use in applications with temperatures above tempering temperature due to resultant loss of mechanical properties

Stainless Steel 440F

  • High carbon content; same as 440C
  • High hardness properties
  • Superior corrosion resistance
  • Allows for heat treating and free machining
  • Ideal for use in applications requiring high hardness, non-galling, and non-seizing properties
  • Not ideal for applications involving gas or liquid under pressure

Learn More

For over thirty years, Continental Steel has been supplying high-quality, reliable metal products to a wide range of industries, from aerospace and medical to construction and military.

We’re proud to offer 440 stainless steel types, all of which meet or exceed some of the industry’s toughest standards, including ASTM, QQ, and MIL-S. To learn more about the benefits of grade 440 stainless steel, or to discuss how we can assist with your next project, contact the team today.

 

Topics: stainless steel

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