MakeItFrom.com
Menu (ESC)

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.

Iron (Fe) 78.4 to 83.4
Chromium (Cr) 16 to 18
Carbon (C) 0.6 to 0.75
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 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