FabDigit

4340M vs 4140 and 2 more: properties

4340M414041505160

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Shear Modulus

78 GPa11.3 Msi
80 GPa11.6 Msi
80 GPa11.6 Msi
80 GPa11.6 Msi

Tensile Strength (Ultimate)

1,550 MPa225 ksi
690 MPa100 ksi
860 MPa125 ksi
725 MPa105 ksi

Yield Strength (0.2% offset)

1,150 MPa167 ksi
480 MPa69.6 ksi
520 MPa75.4 ksi
275 MPa39.9 ksi

Elongation at Break

6%
22%
16%
17%

Reduction in Area

18%
50%
40%
31%

Compressive Strength

1,200 MPa174 ksi
480 MPa69.6 ksi

Shear Strength

930 MPa135 ksi
420 MPa60.9 ksi
560 MPa81.2 ksi
450 MPa65.3 ksi

Fatigue Strength (Endurance Limit)

640 MPa92.8 ksi
345 MPa50 ksi
390 MPa56.6 ksi
330 MPa47.9 ksi

Fracture Toughness (K_IC)

40 MPa·√m36.4 ksi·√in
110 MPa·√m100 ksi·√in

Charpy V-Notch Impact (RT)

10 J7.4 ft·lbf
40 J29.5 ft·lbf
25 J18.4 ft·lbf
25 J18.4 ft·lbf

Hardness, Brinell

444 HB
210 HB
235 HB
197 HB

Hardness, Rockwell C

47 HRC
21 HRC

Hardness, Vickers

470 HV
220 HV
245 HV

Hardness, Rockwell B

94 HRB
92 HRB

Same in both: Elastic (Young's) Modulus 205 GPa29.7 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29

Physical

Density and transition temperatures.

Density

7.83 g/cm³0.28 lb/in³
7.85 g/cm³0.28 lb/in³
7.85 g/cm³0.28 lb/in³
7.85 g/cm³0.28 lb/in³

Melting Point (Solidus)

1,420°C2,588 °F
1,416°C2,581 °F
1,416°C2,581 °F
1,425°C2,597 °F

Liquidus Temperature

1,480°C2,696 °F
1,483°C2,701 °F
1,490°C2,714 °F
1,490°C2,714 °F

Thermal

How each material carries heat and how hot it can run.

Thermal Conductivity

34 W/m·K19.6 BTU/hr·ft·°F
42.6 W/m·K24.6 BTU/hr·ft·°F
42.6 W/m·K24.6 BTU/hr·ft·°F
46 W/m·K26.6 BTU/hr·ft·°F

Specific Heat Capacity

475 J/kg·K0.11 BTU/lb·°F
473 J/kg·K0.11 BTU/lb·°F
473 J/kg·K0.11 BTU/lb·°F
490 J/kg·K0.12 BTU/lb·°F

Thermal Expansion (CTE, 20–100 °C)

11.7 µm/m·K6.5 µin/in·°F
12.3 µm/m·K6.8 µin/in·°F
12.3 µm/m·K6.8 µin/in·°F
12.3 µm/m·K6.8 µin/in·°F

Max Service Temperature (continuous)

290°C554 °F
425°C797 °F
400°C752 °F
250°C482 °F

Min Service Temperature

-73°C-99 °F
-40°C-40 °F
-40°C-40 °F
-40°C-40 °F

Same in both: Latent Heat of Fusion 250 J/g107 BTU/lb

Electrical

Conductivity and insulation.

Electrical Conductivity

7 % IACS
7.8 % IACS
7.8 % IACS
7.8 % IACS

Electrical Resistivity

2.4×10⁻⁷ Ω·m9.45 µΩ·in
2.2×10⁻⁷ Ω·m8.66 µΩ·in
2.2×10⁻⁷ Ω·m8.66 µΩ·in
2.2×10⁻⁷ Ω·m8.66 µΩ·in

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Galvanic Potential (seawater, vs SCE)

-0.6 V
-0.61 V
-0.6 V
-0.61 V

Corrosion Resistance

14 / 100
12 / 100
12 / 100
10 / 100

Manufacturability

FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.

Machinability

15 / 100
60 / 100
45 / 100
55 / 100

Machinability Rating (AISI 1212 = 100 %)

15%
62%
50%
56%

Weldability

12 / 100
40 / 100
25 / 100
25 / 100

Formability (cold)

5 / 100
40 / 100
25 / 100
45 / 100

Castability

25 / 100
35 / 100
40 / 100

Brazeability / Solderability

20 / 100
55 / 100
55 / 100
55 / 100

Polishability

75 / 100
60 / 100
60 / 100
70 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

36 MJ/kg15,477 BTU/lb
32 MJ/kg13,758 BTU/lb
31 MJ/kg13,328 BTU/lb
30 MJ/kg12,898 BTU/lb

Embodied Carbon (primary production)

2.6 kg CO₂/kg
2.2 kg CO₂/kg
2.3 kg CO₂/kg
2.2 kg CO₂/kg

Embodied Water

60 L/kg7.2 gal/lb
55 L/kg6.6 gal/lb
60 L/kg7.2 gal/lb
60 L/kg7.2 gal/lb

Typical Recycled Content

25%
30%
30%
35%

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

198 kN·m/kg
88 kN·m/kg
110 kN·m/kg
92 kN·m/kg

Specific Stiffness (E / density)

26.2 MN·m/kg
26.1 MN·m/kg
26.1 MN·m/kg
26.1 MN·m/kg

Modulus of Resilience

3,226 kJ/m³
562 kJ/m³
660 kJ/m³
184 kJ/m³

Thermal Diffusivity

9.1 mm²/s
11.5 mm²/s
11.5 mm²/s
12 mm²/s

Thermal Shock Resistance Index

22
12
15
13

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.

2005001,0002,0007.588.5Density (g/cm³)Yield strength (MPa) — log scale4140415051604340M

Manufacturing and finishing

Capability4340M414041505160
Casting & forgingYes
Default conditionHRHRHRAnnealed
Relative cost$$ Standard$$ Standard$$$ Premium$$$ Premium
Min. machined wall0.8 mm0.8 mm0.8 mm0.8 mm
Best machined surfaceRa 1.6 µmRa 1.6 µmRa 1.6 µmRa 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.

Ready to make it?

Upload a CAD file and FabDigit prices the part in 4340M and 4140 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.