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.
| Fe | 73.3 to 80.8 | |
| Cr | 17.5 to 19.5 | |
| Mo | 1.8 to 2.5 | |
| Mn | 0 to 1.0 | |
| Si | 0 to 1.0 | |
| Ni | 0 to 1.0 | |
| Nb | 0.2 to 0.8 | |
| Ti | 0.2 to 0.8 | |
| P | 0 to 0.040 | |
| N | 0 to 0.035 | |
| S | 0 to 0.030 | |
| 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