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UNS S44635 (25-4-4) Stainless Steel

S44635 stainless steel is a ferritic stainless steel formulated for primary forming into wrought products. Cited properties are appropriate for the annealed condition. S44635 is the UNS number for this material. 25-4-4 is the common industry name.

It has the highest base cost among wrought ferritic stainless steels. In addition, it has the highest tensile strength and a fairly low thermal conductivity.

The graph bars on the material properties cards below compare S44635 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

240

Elastic (Young's, Tensile) Modulus

210 GPa 30 x 106 psi

Elongation at Break

23 %

Fatigue Strength

390 MPa 56 x 103 psi

Poisson's Ratio

0.27

Rockwell C Hardness

24

Shear Modulus

81 GPa 12 x 106 psi

Shear Strength

450 MPa 65 x 103 psi

Tensile Strength: Ultimate (UTS)

710 MPa 100 x 103 psi

Tensile Strength: Yield (Proof)

580 MPa 84 x 103 psi

Thermal Properties

Latent Heat of Fusion

300 J/g

Maximum Temperature: Corrosion

610 °C 1120 °F

Maximum Temperature: Mechanical

1100 °C 2010 °F

Melting Completion (Liquidus)

1460 °C 2670 °F

Melting Onset (Solidus)

1420 °C 2580 °F

Specific Heat Capacity

470 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

16 W/m-K 9.3 BTU/h-ft-°F

Thermal Expansion

11 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

22 % relative

Density

7.8 g/cm3 490 lb/ft3

Embodied Carbon

4.4 kg CO2/kg material

Embodied Energy

62 MJ/kg 27 x 103 BTU/lb

Embodied Water

170 L/kg 21 gal/lb

Common Calculations

PREN (Pitting Resistance)

39

Resilience: Ultimate (Unit Rupture Work)

150 MJ/m3

Resilience: Unit (Modulus of Resilience)

810 kJ/m3

Stiffness to Weight: Axial

15 points

Stiffness to Weight: Bending

25 points

Strength to Weight: Axial

25 points

Strength to Weight: Bending

23 points

Thermal Diffusivity

4.4 mm2/s

Thermal Shock Resistance

23 points

Alloy Composition

Among wrought stainless steels, the composition of S44635 stainless steel is notable for containing a comparatively high amount of chromium (Cr) and including titanium (Ti). Chromium is the defining alloying element of stainless steel. Higher chromium content imparts additional corrosion resistance. Titanium is used to broadly improve mechanical properties.

Iron (Fe) 61.5 to 68.5
Chromium (Cr) 24.5 to 26
Nickel (Ni) 3.5 to 4.5
Molybdenum (Mo) 3.5 to 4.5
Manganese (Mn) 0 to 1.0
Niobium (Nb) 0.2 to 0.8
Titanium (Ti) 0.2 to 0.8
Silicon (Si) 0 to 0.75
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

Welding Metallurgy and Weldability of Stainless Steels, John C. Lippold and Damian J. Kotecki, 2005

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

CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015