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AISI 444 (S44400) Stainless Steel

AISI 444 stainless steel is a ferritic stainless steel formulated for primary forming into wrought products. Cited properties are appropriate for the annealed condition. 444 is the AISI designation for this material. S44400 is the UNS number.

It has a moderately low electrical conductivity among wrought ferritic stainless steels. In addition, it has a moderately high base cost and a fairly high embodied energy.

The graph bars on the material properties cards below compare AISI 444 stainless steel to: wrought ferritic 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

Brinell Hardness

190

Elastic (Young's, Tensile) Modulus

200 GPa 29 x 106 psi

Elongation at Break

23 %

Fatigue Strength

210 MPa 30 x 103 psi

Poisson's Ratio

0.28

Rockwell B Hardness

83

Shear Modulus

78 GPa 11 x 106 psi

Shear Strength

300 MPa 43 x 103 psi

Tensile Strength: Ultimate (UTS)

470 MPa 69 x 103 psi

Tensile Strength: Yield (Proof)

310 MPa 45 x 103 psi

Thermal Properties

Latent Heat of Fusion

290 J/g

Maximum Temperature: Corrosion

580 °C 1070 °F

Maximum Temperature: Mechanical

930 °C 1710 °F

Melting Completion (Liquidus)

1460 °C 2660 °F

Melting Onset (Solidus)

1420 °C 2580 °F

Specific Heat Capacity

480 J/kg-K 0.11 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

2.2 % IACS

Electrical Conductivity: Equal Weight (Specific)

2.5 % IACS

Otherwise Unclassified Properties

Base Metal Price

15 % relative

Density

7.7 g/cm3 480 lb/ft3

Embodied Carbon

3.4 kg CO2/kg material

Embodied Energy

47 MJ/kg 20 x 103 BTU/lb

Embodied Water

130 L/kg 16 gal/lb

Common Calculations

PREN (Pitting Resistance)

26

Resilience: Ultimate (Unit Rupture Work)

95 MJ/m3

Resilience: Unit (Modulus of Resilience)

240 kJ/m3

Stiffness to Weight: Axial

14 points

Stiffness to Weight: Bending

25 points

Strength to Weight: Axial

17 points

Strength to Weight: Bending

17 points

Thermal Diffusivity

6.2 mm2/s

Thermal Shock Resistance

16 points

Alloy Composition

Among wrought stainless steels, the composition of AISI 444 stainless steel is notable for including titanium (Ti) and niobium (Nb). Titanium is used to broadly improve mechanical properties. Niobium is primarily used to improve yield strength, particularly at elevated temperatures.

Iron (Fe) 73.3 to 80.8
Chromium (Cr) 17.5 to 19.5
Molybdenum (Mo) 1.8 to 2.5
Manganese (Mn) 0 to 1.0
Silicon (Si) 0 to 1.0
Nickel (Ni) 0 to 1.0
Niobium (Nb) 0.2 to 0.8
Titanium (Ti) 0.2 to 0.8
Phosphorus (P) 0 to 0.040
Nitrogen (N) 0 to 0.035
Sulfur (S) 0 to 0.030
Carbon (C) 0 to 0.025

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

Followup Questions

Similar Alloys

Further Reading

ASTM A240: Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications

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