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Steel 9310 vs E4340

Steel · grade comparison

Steel 9310 and E4340 are both steel grades, both aerospace steel. Both yield at about 600 MPa — strength does not separate them. E4340 is harder — 285 HB against 270 HB for 9310 — which matters for wear surfaces and threads. E4340 conducts heat better (44 W/m·K vs 34 W/m·K). On the shop floor, E4340 sits in a lower cost tier (standard, $$) than 9310 (premium, $$$).

E4340Choose it when surface hardness matters, or when cost is the deciding factor.

9310 vs E4340: properties

9310E4340

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Yield Strength (0.2% offset)

600 MPa87 ksi
620 MPa89.9 ksi

Elongation at Break

15%
16%

Compressive Strength

620 MPa89.9 ksi
640 MPa92.8 ksi

Shear Strength

590 MPa85.6 ksi
570 MPa82.7 ksi

Fatigue Strength (Endurance Limit)

430 MPa62.4 ksi
450 MPa65.3 ksi

Fracture Toughness (K_IC)

95 MPa·√m86.5 ksi·√in
90 MPa·√m81.9 ksi·√in

Charpy V-Notch Impact (RT)

60 J44.3 ft·lbf
35 J25.8 ft·lbf

Hardness, Brinell

270 HB
285 HB

Hardness, Rockwell B

98 HRB
—

Hardness, Rockwell C

27 HRC
30 HRC

Hardness, Vickers

284 HV
300 HV

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 · Tensile Strength (Ultimate) 950 MPa138 ksi · Reduction in Area 45%

Physical

Density and transition temperatures.

Melting Point (Solidus)

1,420°C2,588 °F
1,427°C2,601 °F

Liquidus Temperature

1,490°C2,714 °F
1,500°C2,732 °F

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

34 W/m·K19.6 BTU/hr·ft·°F
44 W/m·K25.4 BTU/hr·ft·°F

Thermal Expansion (CTE, 20–100 °C)

11.6 µm/m·K6.4 µin/in·°F
12.3 µm/m·K6.8 µin/in·°F

Latent Heat of Fusion

270 J/g116 BTU/lb
250 J/g107 BTU/lb

Min Service Temperature

-90°C-130 °F
-60°C-76 °F

Same in both: Specific Heat Capacity 475 J/kg·K0.11 BTU/lb·°F · Max Service Temperature (continuous) 400°C752 °F

Electrical

Conductivity and insulation.

Electrical Conductivity

6.6 % IACS
7 % IACS

Electrical Resistivity

2.6×10⁻⁷ Ω·m10.2 µΩ·in
2.48×10⁻⁷ Ω·m9.76 µΩ·in

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Corrosion Resistance

14 / 100
15 / 100

Same in both: Galvanic Potential (seawater, vs SCE) -0.6 V

Manufacturability

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

Machinability

40 / 100
42 / 100

Machinability Rating (AISI 1212 = 100 %)

40%
45%

Weldability

38 / 100
30 / 100

Brazeability / Solderability

55 / 100
50 / 100

Polishability

65 / 100
70 / 100

Castability

—
30 / 100

Same in both: Formability (cold) 35 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

34 MJ/kg14,617 BTU/lb
30 MJ/kg12,898 BTU/lb

Embodied Carbon (primary production)

2.5 kg CO₂/kg
2.3 kg CO₂/kg

Embodied Water

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

Typical Recycled Content

25%
40%

Common Calculations

Ratios derived from the values above.

Modulus of Resilience

878 kJ/m³
938 kJ/m³

Thermal Diffusivity

9.1 mm²/s
11.8 mm²/s

Thermal Shock Resistance Index

14
17

Same in both: Specific Strength (UTS / density) 121 kN·m/kg · 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.

2005001,0002,0007.588.5Density (g/cm³)Yield strength (MPa) — log scale9310E4340

Manufacturing and finishing

Capability9310E4340
Default conditionHRHR
Relative cost$$$ Premium$$ Standard
Min. machined wall0.8 mm0.8 mm
Best machined surfaceRa 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.

9310 vs E4340 — frequently asked

What is the difference between 9310 and E4340?

Steel 9310 and E4340 are both steel grades, both aerospace steel. Both yield at about 600 MPa — strength does not separate them. E4340 is harder — 285 HB against 270 HB for 9310 — which matters for wear surfaces and threads.

Which is cheaper, 9310 or E4340?

E4340 is the lower-cost material: it sits in the standard tier ($$) while 9310 is premium ($$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.

Which welds better, 9310 or E4340?

9310. Its weldability rates fair (38/100) against poor (30/100) for E4340.

Ready to make it?

Upload a CAD file and FabDigit prices the part in 9310 and E4340 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.