Stainless Steel 303 vs 420F
Stainless Steel · grade comparison
Stainless Steel 303 and 420F are both stainless steel grades, both machining-friendly ss. 303 is the stronger of the two: yield strength 450 MPa (65.3 ksi) against 380 MPa (55.1 ksi) for 420F, about 18% more. 303 is the more ductile: elongation 30% versus 20% for 420F, and 303 is harder (240 HB vs 220 HB). 303 runs hotter in service (760°C vs 400°C continuous) and 420F conducts heat better (24.9 W/m·K vs 16.2 W/m·K). On the shop floor, 303 machines more easily (very good vs good), 303 welds better (poor vs not recommended), and 420F sits in a lower cost tier (standard, $$) than 303 (premium, $$$).
303Choose it when strength drives the design, or when the part is bent, formed or impact-loaded.
420FChoose it when cost is the deciding factor.
303 vs 420F: 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.
Elastic (Young's) Modulus
Shear Modulus
Bulk Modulus
Poisson's Ratio
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
Physical
Density and transition temperatures.
Density
Melting Point (Solidus)
Liquidus Temperature
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Latent Heat of Fusion
Max Service Temperature (continuous)
Min Service Temperature
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Galvanic Potential (seawater, vs SCE)
Corrosion Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Brazeability / Solderability
Polishability
Castability
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Same in both: Typical Recycled Content 65%
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Modulus of Resilience
Thermal Diffusivity
Thermal Shock Resistance Index
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 | 303 | 420F |
|---|---|---|
| Default condition | Cold Drawn | Annealed |
| Relative cost | $$$ Premium | $$ Standard |
| 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.
303 vs 420F — frequently asked
Is 303 stronger than 420F?
Yes. 303 has a typical yield strength of 450 MPa (65.3 ksi) against 380 MPa (55.1 ksi) for 420F — about 18% more. Tensile strength is 655 MPa (95 ksi) vs 690 MPa (100 ksi).
Which is cheaper, 303 or 420F?
420F is the lower-cost material: it sits in the standard tier ($$) while 303 is premium ($$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
Which is easier to machine, 303 or 420F?
303. Its machinability rates very good (72/100) against good (58/100) for 420F; for welding the order is 303 first (poor, 25/100) then 420F (not recommended, 12/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 303 and 420F 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.