Stainless Steel 420 vs 431
Stainless Steel · grade comparison
Stainless Steel 420 and 431 are both stainless steel grades, both high strength ss. 431 is the stronger of the two: yield strength 760 MPa (110 ksi) against 360 MPa (52.2 ksi) for 420, about 111% more; tensile strength follows at 950 MPa (138 ksi) vs 690 MPa (100 ksi). In exchange, 420 is the more ductile: elongation 22% versus 16% for 431, and 431 is harder (300 HB vs 200 HB). 420 runs hotter in service (650°C vs 450°C continuous) and 420 conducts heat better (24.9 W/m·K vs 20.2 W/m·K). On the shop floor, 420 machines more easily (45 vs 35 out of 100).
420Choose it when the part is bent, formed or impact-loaded, or when the part sees heat.
431Choose it when strength drives the design.
420 vs 431: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all stainless steel grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all stainless steel grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Shear Modulus
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Vickers
Hardness, Rockwell C
Same in both: Elastic (Young's) Modulus 200 GPa29 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29
Physical
Density and transition temperatures.
Melting Point (Solidus)
Same in both: Density 7.75 g/cm³0.28 lb/in³ · Liquidus Temperature 1,510°C2,750 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Same in both: Specific Heat Capacity 460 J/kg·K0.11 BTU/lb·°F · Latent Heat of Fusion 260 J/g112 BTU/lb · Min Service Temperature -30°C-22 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Same in both: Galvanic Potential (seawater, vs SCE) -0.3 V
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Formability (cold)
Castability
Brazeability / Solderability
Polishability
Same in both: Weldability 25 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Modulus of Resilience
Thermal Diffusivity
Same in both: Specific Stiffness (E / density) 25.8 MN·m/kg · Thermal Shock Resistance Index 8
Strength versus weight
Yield strength against density for every stainless steel grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | 420 | 431 |
|---|---|---|
| Sheet metal | — | Yes |
| Default condition | Annealed | Hardened & Tempered |
| Relative cost | $$$ Premium | $$$ Premium |
| Min. machined wall | 0.8 mm | 0.8 mm |
| Best machined surface | Ra 1.6 µm | Ra 1.6 µm |
Both are offered for CNC machining. Both take the same 32 finishes: AlCrN, AlTiN, Black Oxide, CVD Al2O3, CVD TiCN, CVD TiN, Cerakote, Chrome Plating, CrN, DLC, Electroless Nickel (EN), Electropolishing and 20 more.
420 vs 431 — frequently asked
Is 431 stronger than 420?
Yes. 431 has a typical yield strength of 760 MPa (110 ksi) against 360 MPa (52.2 ksi) for 420 — about 111% more. Tensile strength is 950 MPa (138 ksi) vs 690 MPa (100 ksi).
Which is cheaper, 420 or 431?
Both sit in the same relative cost tier ($$$, premium); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, 420 or 431?
420, by a small margin. Both rate fair for machinability — 45/100 against 35/100 for 431.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 420 and 431 side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.