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.
| Fe | 61.5 to 68.5 | |
| Cr | 24.5 to 26 | |
| Ni | 3.5 to 4.5 | |
| Mo | 3.5 to 4.5 | |
| Mn | 0 to 1.0 | |
| Nb | 0.2 to 0.8 | |
| Ti | 0.2 to 0.8 | |
| Si | 0 to 0.75 | |
| 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
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