Steel 4340 vs HC340LA
Steel · grade comparison
Steel 4340 and HC340LA are both steel grades, both high strength steel. 4340 is the stronger of the two: yield strength 620 MPa (89.9 ksi) against 370 MPa (53.7 ksi) for HC340LA, about 68% more; tensile strength follows at 950 MPa (138 ksi) vs 460 MPa (66.7 ksi). In exchange, HC340LA is the more ductile: elongation 26% versus 18% for 4340, and 4340 is harder (285 HB vs 138 HB). 4340 runs hotter in service (400°C vs 300°C continuous) and HC340LA conducts electricity better (9.5 % IACS vs 7 % IACS). On the shop floor, HC340LA machines more easily (good vs fair), HC340LA welds better (excellent vs poor), and HC340LA sits in a lower cost tier (standard, $$) than 4340 (premium, $$$).
4340Choose it when strength drives the design, or when the part sees heat.
HC340LAChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
4340 vs HC340LA: 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.
Elastic (Young's) Modulus
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, Rockwell C
Hardness, Vickers
Same in both: Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29
Physical
Density and transition temperatures.
Melting Point (Solidus)
Liquidus Temperature
Same in both: Density 7.85 g/cm³0.28 lb/in³
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)
Same in both: Min Service Temperature -40°C-40 °F
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)
Castability
Brazeability / Solderability
Polishability
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Water
Typical Recycled Content
Same in both: Embodied Carbon (primary production) 2.3 kg CO₂/kg
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 steel grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | 4340 | HC340LA |
|---|---|---|
| CNC machining | Yes | — |
| Default condition | HR | HR |
| Relative cost | $$$ Premium | $$ Standard |
| Min. machined wall | 0.8 mm | — |
| Best machined surface | Ra 1.6 µm | — |
| AlCrN | Yes | — |
| AlTiN | Yes | — |
| CVD Al2O3 | Yes | — |
| CVD TiCN | Yes | — |
| CVD TiN | Yes | — |
| CrN | Yes | — |
| DLC | Yes | — |
| HVOF Coating | Yes | — |
| MoS2 | Yes | — |
| Multilayer CVD | Yes | — |
| TiAlN | Yes | — |
| TiB2 | Yes | — |
| TiCN | Yes | — |
| TiN | Yes | — |
| WC/C | Yes | — |
| ZrN | Yes | — |
Both are offered for Sheet metal. They share 22 finishes: Black Oxide, Cerakote, Chrome Plating, Copper Plating, E-Coating, Electroless Nickel (EN), Epoxy Coating, Gold Plating, Hard Chrome Plating, Hot-Dip Galvanizing, Manganese Phosphate, Nickel Plating and 10 more.
4340 vs HC340LA — frequently asked
Is 4340 stronger than HC340LA?
Yes. 4340 has a typical yield strength of 620 MPa (89.9 ksi) against 370 MPa (53.7 ksi) for HC340LA — about 68% more. Tensile strength is 950 MPa (138 ksi) vs 460 MPa (66.7 ksi).
Which is cheaper, 4340 or HC340LA?
HC340LA is the lower-cost material: it sits in the standard tier ($$) while 4340 is premium ($$$). 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, 4340 or HC340LA?
HC340LA. Its machinability rates good (60/100) against fair (48/100) for 4340; for welding the order is HC340LA first (excellent, 88/100) then 4340 (poor, 33/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 4340 and HC340LA 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.