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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.

Iron (Fe) 82.4 to 87.6
Chromium (Cr) 12 to 14
Manganese (Mn) 0 to 1.3
Silicon (Si) 0 to 1.0
Carbon (C) 0.3 to 0.4
Sulfur (S) 0.15 to 0.35
Molybdenum (Mo) 0 to 0.5
Phosphorus (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