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.
| Fe | 78 to 83.1 | |
| Cr | 16 to 18 | |
| C | 1.0 to 1.2 | |
| Mn | 0 to 1.0 | |
| Si | 0 to 1.0 | |
| Mo | 0 to 0.75 | |
| P | 0 to 0.040 | |
| 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