Steel 4118 vs 4820
Steel · grade comparison
Steel 4118 and 4820 are both steel grades. 4820 is the stronger of the two: yield strength 450 MPa (65.3 ksi) against 350 MPa (50.8 ksi) for 4118, about 29% more; tensile strength follows at 700 MPa (102 ksi) vs 530 MPa (76.9 ksi). In exchange, 4118 is the more ductile: elongation 26% versus 20% for 4820, and 4820 is harder (200 HB vs 149 HB). 4118 runs hotter in service (400°C vs 250°C continuous) and 4118 conducts heat better (42 W/m·K vs 34 W/m·K). On the shop floor, 4118 welds better (good vs fair) and 4118 sits in a lower cost tier (budget, $) than 4820 (standard, $$).
4118Choose it when the part is bent, formed or impact-loaded, or when the part sees heat.
4820Choose it when strength drives the design.
4118 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
Reduction in Area
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Compressive Strength
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
Physical
Density and transition temperatures.
Density
Liquidus Temperature
Same in both: Melting Point (Solidus) 1,425°C2,597 °F
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)
Same in both: Corrosion Resistance 12 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Polishability
Same in both: Brazeability / Solderability 60 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Typical Recycled Content
Same in both: Embodied Water 60 L/kg7.2 gal/lb
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 | 4118 | 4820 |
|---|---|---|
| CNC machining | — | Yes |
| Sheet metal | — | Yes |
| Default condition | — | HR |
| Relative cost | $ Budget | $$ Standard |
| Min. machined wall | — | 0.8 mm |
| Best machined surface | — | Ra 1.6 µm |
| AlCrN | — | Yes |
| AlTiN | — | Yes |
| Black Oxide | — | Yes |
| CVD Al2O3 | — | Yes |
| CVD TiCN | — | Yes |
| CVD TiN | — | Yes |
| Cerakote | — | Yes |
| Chrome Plating | — | Yes |
| CrN | — | Yes |
| DLC | — | Yes |
| E-Coating | — | Yes |
| HVOF Coating | — | Yes |
| Hot-Dip Galvanizing | — | Yes |
| MoS2 | — | Yes |
| Multilayer CVD | — | Yes |
| Nickel Plating | — | Yes |
| PTFE Coating | — | Yes |
| Painting | — | Yes |
They share 9 finishes: Copper Plating, Electroless Nickel (EN), Epoxy Coating, Gold Plating, Hard Chrome Plating, Manganese Phosphate, Plasma Spray, Silver Plating, Zinc Phosphate.
4118 vs 4820 — frequently asked
Is 4820 stronger than 4118?
Yes. 4820 has a typical yield strength of 450 MPa (65.3 ksi) against 350 MPa (50.8 ksi) for 4118 — about 29% more. Tensile strength is 700 MPa (102 ksi) vs 530 MPa (76.9 ksi).
Which is cheaper, 4118 or 4820?
4118 is the lower-cost material: it sits in the budget tier ($) while 4820 is standard ($$). 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, 4118 or 4820?
4118. Its machinability rates good (60/100) against fair (52/100) for 4820; for welding the order is 4118 first (good, 60/100) then 4820 (fair, 40/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 4118 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.