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AISI 420 (S42000) Stainless Steel

AISI 420 stainless steel is a martensitic stainless steel formulated for primary forming into wrought products. 420 is the AISI designation for this material. S42000 is the UNS number. Additionally, the British Standard (BS) designation is 420S29.

It can have a moderately low ductility and has a moderately high electrical conductivity among wrought martensitic stainless steels.

The properties of AISI 420 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 420 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

190

Elastic (Young's, Tensile) Modulus

190 GPa 28 x 106 psi

Elongation at Break

8.0 to 15 %

Fatigue Strength

220 to 670 MPa 33 to 97 x 103 psi

Poisson's Ratio

0.28

Rockwell B Hardness

84

Shear Modulus

76 GPa 11 x 106 psi

Shear Strength

420 to 1010 MPa 61 to 150 x 103 psi

Tensile Strength: Ultimate (UTS)

690 to 1720 MPa 100 to 250 x 103 psi

Tensile Strength: Yield (Proof)

380 to 1310 MPa 55 to 190 x 103 psi

Thermal Properties

Latent Heat of Fusion

280 J/g

Maximum Temperature: Corrosion

390 °C 730 °F

Maximum Temperature: Mechanical

620 °C 1150 °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

27 W/m-K 16 BTU/h-ft-°F

Thermal Expansion

10 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

3.0 % IACS

Electrical Conductivity: Equal Weight (Specific)

3.5 % IACS

Otherwise Unclassified Properties

Base Metal Price

7.5 % 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)

88 to 130 MJ/m3

Resilience: Unit (Modulus of Resilience)

380 to 4410 kJ/m3

Stiffness to Weight: Axial

14 points

Stiffness to Weight: Bending

25 points

Strength to Weight: Axial

25 to 62 points

Strength to Weight: Bending

22 to 41 points

Thermal Diffusivity

7.3 mm2/s

Thermal Shock Resistance

25 to 62 points

Alloy Composition

Among wrought stainless steels, the composition of AISI 420 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) 82.3 to 87.9
Chromium (Cr) 12 to 14
Manganese (Mn) 0 to 1.0
Silicon (Si) 0 to 1.0
Nickel (Ni) 0 to 0.75
Carbon (C) 0.15 to 0.4
Molybdenum (Mo) 0 to 0.5
Phosphorus (P) 0 to 0.040
Sulfur (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 A276: Standard Specification for Stainless Steel Bars and Shapes

Advanced Materials in Automotive Engineering, Jason Rowe (editor), 2012

Welding Metallurgy of Stainless Steels, Erich Folkhard et al., 2012

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