AISI 431 (S43100) Stainless Steel
AISI 431 stainless steel is a martensitic stainless steel formulated for primary forming into wrought products. 431 is the AISI designation for this material. S43100 is the UNS number. Additionally, the British Standard (BS) designation is 431S29.
It can have a moderately high tensile strength among the wrought martensitic stainless steels in the database.
The properties of AISI 431 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 431 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
Brinell Hardness
250
Elastic (Young's, Tensile) Modulus
200 GPa 28 x 106 psi
Elongation at Break
15 to 17 %
Fatigue Strength
430 to 610 MPa 62 to 88 x 103 psi
Poisson's Ratio
0.28
Rockwell C Hardness
26
Shear Modulus
77 GPa 11 x 106 psi
Shear Strength
550 to 840 MPa 80 to 120 x 103 psi
Tensile Strength: Ultimate (UTS)
890 to 1380 MPa 130 to 200 x 103 psi
Tensile Strength: Yield (Proof)
710 to 1040 MPa 100 to 150 x 103 psi
Thermal Properties
Latent Heat of Fusion
280 J/g
Maximum Temperature: Corrosion
400 °C 760 °F
Maximum Temperature: Mechanical
850 °C 1550 °F
Melting Completion (Liquidus)
1510 °C 2750 °F
Melting Onset (Solidus)
1450 °C 2640 °F
Specific Heat Capacity
480 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
26 W/m-K 15 BTU/h-ft-°F
Thermal Expansion
12 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
2.6 % IACS
Electrical Conductivity: Equal Weight (Specific)
3.0 % 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)
16
Resilience: Ultimate (Unit Rupture Work)
140 to 180 MJ/m3
Resilience: Unit (Modulus of Resilience)
1270 to 2770 kJ/m3
Stiffness to Weight: Axial
14 points
Stiffness to Weight: Bending
25 points
Strength to Weight: Axial
32 to 50 points
Strength to Weight: Bending
27 to 36 points
Thermal Diffusivity
7.0 mm2/s
Thermal Shock Resistance
28 to 43 points
Alloy Composition
Among wrought stainless steels, the composition of AISI 431 stainless steel is notable for containing comparatively high amounts of chromium (Cr) and nickel (Ni). Chromium is the defining alloying element of stainless steel. Higher chromium content imparts additional corrosion resistance. Nickel is primarily used to achieve a specific microstructure. In addition, it has a beneficial effect on mechanical properties and certain types of corrosion.
| Fe | 78.2 to 83.8 | |
| Cr | 15 to 17 | |
| Ni | 1.3 to 2.5 | |
| Mn | 0 to 1.0 | |
| Si | 0 to 1.0 | |
| C | 0 to 0.2 | |
| P | 0 to 0.040 | |
| S | 0 to 0.030 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM A176: Standard Specification for Stainless and Heat-Resisting Chromium Steel Plate, Sheet, and Strip
ASTM A473: Standard Specification for Stainless Steel Forgings
ASTM A479: Standard Specification for Stainless Steel Bars and Shapes for Use in Boilers and Other Pressure Vessels
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
Pressure Vessels: External Pressure Technology, 2nd ed., Carl T. F. Ross, 2011
Corrosion of Stainless Steels, A. John Sedriks, 1996
ASM Specialty Handbook: Stainless Steels, J. R. Davis (editor), 1994