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AISI 440C (S44004) Stainless Steel

AISI 440C stainless steel is a martensitic stainless steel formulated for primary forming into wrought products. 440C is the AISI designation for this material. S44004 is the UNS number.

It can have the highest tensile strength among wrought martensitic stainless steels. In addition, it can have the lowest ductility and has a moderately low electrical conductivity.

The properties of AISI 440C stainless steel include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare AISI 440C stainless steel to: wrought martensitic stainless steels (top), all iron alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

Mechanical Properties

Elastic (Young's, Tensile) Modulus

200 GPa 28 x 106 psi

Elongation at Break

2.0 to 14 %

Fatigue Strength

260 to 840 MPa 38 to 120 x 103 psi

Poisson's Ratio

0.28

Shear Modulus

76 GPa 11 x 106 psi

Shear Strength

430 to 1120 MPa 63 to 160 x 103 psi

Tensile Strength: Ultimate (UTS)

710 to 1970 MPa 100 to 290 x 103 psi

Tensile Strength: Yield (Proof)

450 to 1900 MPa 65 to 280 x 103 psi

Thermal Properties

Latent Heat of Fusion

280 J/g

Maximum Temperature: Corrosion

390 °C 730 °F

Maximum Temperature: Mechanical

870 °C 1600 °F

Melting Completion (Liquidus)

1480 °C 2700 °F

Melting Onset (Solidus)

1370 °C 2500 °F

Specific Heat Capacity

480 J/kg-K 0.12 BTU/lb-°F

Thermal Conductivity

22 W/m-K 13 BTU/h-ft-°F

Thermal Expansion

10 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

2.4 % IACS

Electrical Conductivity: Equal Weight (Specific)

2.8 % IACS

Otherwise Unclassified Properties

Base Metal Price

9.0 % relative

Density

7.7 g/cm3 480 lb/ft3

Embodied Carbon

2.2 kg CO2/kg material

Embodied Energy

31 MJ/kg 13 x 103 BTU/lb

Embodied Water

120 L/kg 14 gal/lb

Common Calculations

PREN (Pitting Resistance)

18

Resilience: Ultimate (Unit Rupture Work)

39 to 88 MJ/m3

Stiffness to Weight: Axial

14 points

Stiffness to Weight: Bending

25 points

Strength to Weight: Axial

26 to 71 points

Strength to Weight: Bending

23 to 46 points

Thermal Diffusivity

6.0 mm2/s

Thermal Shock Resistance

26 to 71 points

Alloy Composition

Among wrought stainless steels, the composition of AISI 440C stainless steel is notable for containing a comparatively high amount of carbon (C). Carbon is used to increase strength at the cost of a decrease in toughness and corrosion resistance.

Iron (Fe) 78 to 83.1
Chromium (Cr) 16 to 18
Carbon (C) 1.0 to 1.2
Manganese (Mn) 0 to 1.0
Silicon (Si) 0 to 1.0
Molybdenum (Mo) 0 to 0.75
Phosphorus (P) 0 to 0.040
Sulfur (S) 0 to 0.015

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

ASTM A493: Standard Specification for Stainless Steel Wire and Wire Rods for Cold Heading and Cold Forging

ASTM A276: Standard Specification for Stainless Steel Bars and Shapes

Creep-Resistant Steels, Fujio Abe et al. (editors), 2008

Welding Metallurgy and Weldability of Stainless Steels, John C. Lippold and Damian J. Kotecki, 2005

Advanced Materials in Automotive Engineering, Jason Rowe (editor), 2012

ASTM A959: Standard Guide for Specifying Harmonized Standard Grade Compositions for Wrought Stainless Steels

Properties and Selection: Irons, Steels and High Performance Alloys, ASM Handbook vol. 1, ASM International, 1993

Corrosion of Stainless Steels, A. John Sedriks, 1996

ASM Specialty Handbook: Stainless Steels, J. R. Davis (editor), 1994

Advances in Stainless Steels, Baldev Raj et al. (editors), 2010