AISI 440A (S44002) Stainless Steel
AISI 440A stainless steel is a martensitic stainless steel formulated for primary forming into wrought products. 440A is the AISI designation for this material. S44002 is the UNS number. It has a moderately low thermal conductivity among the wrought martensitic stainless steels in the database.
The properties of AISI 440A 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 440A 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
5.0 to 20 %
Fatigue Strength
270 to 790 MPa 39 to 110 x 103 psi
Poisson's Ratio
0.28
Shear Modulus
77 GPa 11 x 106 psi
Shear Strength
450 to 1040 MPa 66 to 150 x 103 psi
Tensile Strength: Ultimate (UTS)
730 to 1790 MPa 110 to 260 x 103 psi
Tensile Strength: Yield (Proof)
420 to 1650 MPa 60 to 240 x 103 psi
Thermal Properties
Latent Heat of Fusion
280 J/g
Maximum Temperature: Corrosion
400 °C 750 °F
Maximum Temperature: Mechanical
760 °C 1400 °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
23 W/m-K 13 BTU/h-ft-°F
Thermal Expansion
10 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
2.5 % IACS
Electrical Conductivity: Equal Weight (Specific)
2.9 % 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)
87 to 120 MJ/m3
Stiffness to Weight: Axial
14 points
Stiffness to Weight: Bending
25 points
Strength to Weight: Axial
26 to 65 points
Strength to Weight: Bending
23 to 43 points
Thermal Diffusivity
6.2 mm2/s
Thermal Shock Resistance
26 to 65 points
Alloy Composition
Among wrought stainless steels, the composition of AISI 440A stainless steel is notable for containing a comparatively high amount of chromium (Cr). Chromium is the defining alloying element of stainless steel. Higher chromium content imparts additional corrosion resistance.
| Fe | 78.4 to 83.4 | |
| Cr | 16 to 18 | |
| C | 0.6 to 0.75 | |
| 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 A276: Standard Specification for Stainless Steel Bars and Shapes
Creep-Resistant Steels, Fujio Abe et al. (editors), 2008
Advanced Materials in Automotive Engineering, Jason Rowe (editor), 2012
ASTM A959: Standard Guide for Specifying Harmonized Standard Grade Compositions for Wrought Stainless Steels
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