AISI 420F (S42020) Stainless Steel
AISI 420F stainless steel is a martensitic stainless steel formulated for primary forming into wrought products. Cited properties are appropriate for the annealed condition. 420F is the AISI designation for this material. S42020 is the UNS number.
It has a moderately high electrical conductivity and a moderately low tensile strength among wrought martensitic stainless steels.
The graph bars on the material properties cards below compare AISI 420F 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
230
Elastic (Young's, Tensile) Modulus
190 GPa 28 x 106 psi
Elongation at Break
18 %
Fatigue Strength
270 MPa 39 x 103 psi
Poisson's Ratio
0.28
Shear Modulus
76 GPa 11 x 106 psi
Shear Strength
460 MPa 66 x 103 psi
Tensile Strength: Ultimate (UTS)
740 MPa 110 x 103 psi
Tensile Strength: Yield (Proof)
430 MPa 63 x 103 psi
Thermal Properties
Latent Heat of Fusion
270 J/g
Maximum Temperature: Corrosion
390 °C 730 °F
Maximum Temperature: Mechanical
760 °C 1400 °F
Melting Completion (Liquidus)
1440 °C 2620 °F
Melting Onset (Solidus)
1390 °C 2540 °F
Specific Heat Capacity
480 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
25 W/m-K 15 BTU/h-ft-°F
Thermal Expansion
10 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
3.1 % IACS
Electrical Conductivity: Equal Weight (Specific)
3.7 % IACS
Otherwise Unclassified Properties
Base Metal Price
7.0 % relative
Density
7.7 g/cm3 480 lb/ft3
Embodied Carbon
2.0 kg CO2/kg material
Embodied Energy
28 MJ/kg 12 x 103 BTU/lb
Embodied Water
100 L/kg 12 gal/lb
Common Calculations
PREN (Pitting Resistance)
14
Resilience: Ultimate (Unit Rupture Work)
120 MJ/m3
Resilience: Unit (Modulus of Resilience)
480 kJ/m3
Stiffness to Weight: Axial
14 points
Stiffness to Weight: Bending
25 points
Strength to Weight: Axial
27 points
Strength to Weight: Bending
23 points
Thermal Diffusivity
6.8 mm2/s
Thermal Shock Resistance
27 points
Alloy Composition
Among wrought stainless steels, the composition of AISI 420F stainless steel is notable for containing comparatively high amounts of chromium (Cr) and manganese (Mn). Chromium is the defining alloying element of stainless steel. Higher chromium content imparts additional corrosion resistance. Manganese is used to improve ductility at elevated temperatures. It also permits a higher nitrogen content than would otherwise be possible.
| Fe | 82.4 to 87.6 | |
| Cr | 12 to 14 | |
| Mn | 0 to 1.3 | |
| Si | 0 to 1.0 | |
| C | 0.3 to 0.4 | |
| S | 0.15 to 0.35 | |
| Mo | 0 to 0.5 | |
| P | 0 to 0.060 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM A895: Standard Specification for Free-Machining Stainless Steel Plate, Sheet, and Strip
Creep-Resistant Steels, Fujio Abe et al. (editors), 2008
Welding Metallurgy and Weldability of Stainless Steels, John C. Lippold and Damian J. Kotecki, 2005
Advanced Materials in Automotive Engineering, Jason Rowe (editor), 2012
Properties and Selection: Irons, Steels and High Performance Alloys, ASM Handbook vol. 1, ASM International, 1993
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