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.
| Fe | 82.3 to 87.9 | |
| Cr | 12 to 14 | |
| Mn | 0 to 1.0 | |
| Si | 0 to 1.0 | |
| Ni | 0 to 0.75 | |
| C | 0.15 to 0.4 | |
| Mo | 0 to 0.5 | |
| 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 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