Steel 4340 vs M2
Steel · grade comparison
Steel 4340 and M2 are both steel grades. 4340 is the stronger of the two: yield strength 620 MPa (89.9 ksi) against 570 MPa (82.7 ksi) for M2, about 9% more; tensile strength follows at 950 MPa (138 ksi) vs 900 MPa (131 ksi). 4340 is the more ductile: elongation 18% versus 12% for M2, and 4340 is harder (285 HB vs 235 HB). 4340 is lighter (7.85 g/cm³ vs 8.16 g/cm³ for M2) and M2 is stiffer (217 GPa vs 205 GPa). On the shop floor, 4340 machines more easily (48 vs 35 out of 100), 4340 welds better (33 vs 18 out of 100), and 4340 sits in a lower cost tier (premium, $$$) than M2 (specialty, $$$$$).
4340Choose it when strength drives the design, or when the part is bent, formed or impact-loaded.
4340 vs M2: 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
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)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Rockwell C
Hardness, Vickers
Same in both: Bulk Modulus 160 GPa23.2 Msi · Charpy V-Notch Impact (RT) 30 J22.1 ft·lbf
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)
Min Service Temperature
Same in both: Latent Heat of Fusion 250 J/g107 BTU/lb · Max Service Temperature (continuous) 400°C752 °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
Same in both: Polishability 70 / 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)
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 | M2 |
|---|---|---|
| Sheet metal | Yes | — |
| Default condition | HR | Annealed |
| Relative cost | $$$ Premium | $$$$$ Specialty |
| Min. machined wall | 0.8 mm | 0.8 mm |
| Best machined surface | Ra 1.6 µm | Ra 1.6 µm |
Both are offered for CNC machining. Both take the same 38 finishes: AlCrN, AlTiN, Black Oxide, CVD Al2O3, CVD TiCN, CVD TiN, Cerakote, Chrome Plating, Copper Plating, CrN, DLC, E-Coating and 26 more.
4340 vs M2 — frequently asked
Is 4340 stronger than M2?
Yes. 4340 has a typical yield strength of 620 MPa (89.9 ksi) against 570 MPa (82.7 ksi) for M2 — about 9% more. Tensile strength is 950 MPa (138 ksi) vs 900 MPa (131 ksi).
Which is cheaper, 4340 or M2?
4340 is the lower-cost material: it sits in the premium tier ($$$) while M2 is specialty ($$$$$). 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 M2?
4340, by a small margin. Both rate fair for machinability — 48/100 against 35/100 for M2; for welding the order is 4340 first (poor, 33/100) then M2 (poor, 18/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 4340 and M2 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.