Steel 4320 vs 4820
Steel · grade comparison
Steel 4320 and 4820 are both steel grades, both case hardening steel. 4820 is the stronger of the two: yield strength 450 MPa (65.3 ksi) against 415 MPa (60.2 ksi) for 4320, about 8% more; tensile strength follows at 700 MPa (102 ksi) vs 640 MPa (92.8 ksi). 4820 is harder — 200 HB against 187 HB for 4320 — which matters for wear surfaces and threads. 4320 runs hotter in service (350°C vs 250°C continuous) and 4320 conducts heat better (44 W/m·K vs 34 W/m·K). On the shop floor, 4820 forms better (good vs fair) and 4820 sits in a lower cost tier (standard, $$) than 4320 (premium, $$$).
4320Choose it when the part sees heat.
4820Choose it when strength drives the design, or when surface hardness matters.
4320 vs 4820: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all 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 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.
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Shear Strength
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Compressive Strength
Fracture Toughness (K_IC)
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 205 GPa29.7 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Reduction in Area 50%
Physical
Density and transition temperatures.
Density
Same in both: Melting Point (Solidus) 1,425°C2,597 °F · Liquidus Temperature 1,500°C2,732 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Same in both: Latent Heat of Fusion 270 J/g116 BTU/lb
Electrical
Conductivity and insulation.
Electrical Resistivity
Electrical Conductivity
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
Formability (cold)
Brazeability / Solderability
Polishability
Same in both: Machinability Rating (AISI 1212 = 100 %) 55% · Weldability 40 / 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
Thermal Shock Resistance Index
Same in both: Specific Stiffness (E / density) 26.1 MN·m/kg
Strength versus weight
Yield strength against density for every steel grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | 4320 | 4820 |
|---|---|---|
| Default condition | HR | HR |
| 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 and Sheet metal. Both take the same 38 finishes: AlCrN, AlTiN, Black Oxide, CVD Al2O3, CVD TiCN, CVD TiN, Cerakote, Chrome Plating, Copper Plating, CrN, DLC, E-Coating and 26 more.
4320 vs 4820 — frequently asked
Is 4820 stronger than 4320?
Yes. 4820 has a typical yield strength of 450 MPa (65.3 ksi) against 415 MPa (60.2 ksi) for 4320 — about 8% more. Tensile strength is 700 MPa (102 ksi) vs 640 MPa (92.8 ksi).
Which is cheaper, 4320 or 4820?
4820 is the lower-cost material: it sits in the standard tier ($$) while 4320 is premium ($$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
When should I choose 4320 over 4820?
Pick 4320 when the part sees heat. Pick 4820 when strength drives the design, or when surface hardness matters.
Ready to make it?
Upload a CAD file and FabDigit prices the part in 4320 and 4820 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.