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C vs G-9

Composite · grade comparison

C and G-9 are both composite grades. G-9 is the stronger of the two: tensile strength 240 MPa (34.8 ksi) against 76 MPa (11 ksi) for C, about 3.2 times as much. C is lighter (1.36 g/cm³ vs 1.95 g/cm³ for G-9) and G-9 is stiffer (19 GPa vs 7 GPa). On the shop floor, C machines more easily (very good vs poor) and C sits in a lower cost tier (premium, $$$) than G-9 (high, $$$$).

CChoose it when weight is the constraint, or when the part is machined in volume.

G-9Choose it when strength drives the design, or when the part sees heat.

C vs G-9: properties

CG-9

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

7 GPa1 Msi
19 GPa2.8 Msi

Shear Modulus

2.6 GPa0.38 Msi
—

Poisson's Ratio

0.3
0.16

Tensile Strength (Ultimate)

76 MPa11 ksi
240 MPa34.8 ksi

Elongation at Break

1.5%
—

Compressive Strength

275 MPa39.9 ksi
345 MPa50 ksi

Compressive Modulus

6.5 GPa0.94 Msi
15 GPa2.2 Msi

Flexural Strength

120 MPa17.4 ksi
310 MPa45 ksi

Flexural Modulus

7.5 GPa1.1 Msi
18 GPa2.6 Msi

Shear Strength

90 MPa13.1 ksi
120 MPa17.4 ksi

Izod Impact, Notched

170 J/m3.2 ft·lbf/in
400 J/m7.5 ft·lbf/in

Hardness, Rockwell M

105 HRM
115 HRM

Physical

Density and transition temperatures.

Density

1.36 g/cm³0.05 lb/in³
1.95 g/cm³0.07 lb/in³

Glass Transition (Tg)

160°C320 °F
—

Water Absorption (24 h)

1.6%
0.8%

Water Absorption (Saturation)

4%
1.8%

Thermal

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

Thermal Conductivity

0.3 W/m·K0.17 BTU/hr·ft·°F
0.32 W/m·K0.18 BTU/hr·ft·°F

Specific Heat Capacity

1,400 J/kg·K0.33 BTU/lb·°F
1,100 J/kg·K0.26 BTU/lb·°F

Thermal Expansion (CTE, 20–100 °C)

25 µm/m·K13.9 µin/in·°F
14 µm/m·K7.8 µin/in·°F

Max Service Temperature (continuous)

120°C248 °F
155°C311 °F

Min Service Temperature

-50°C-58 °F
-60°C-76 °F

Limiting Oxygen Index

30%
42%

Max Service Temperature (short-term)

150°C302 °F
200°C392 °F

Electrical

Conductivity and insulation.

Electrical Resistivity

1×10⁹ Ω·m3.94×10¹⁶ µΩ·in
1×10¹¹ Ω·m3.94×10¹⁸ µΩ·in

Dielectric Strength

10 kV/mm254 V/mil
12 kV/mm305 V/mil

Dielectric Constant (1 MHz)

5.5
6.5

Dissipation Factor (1 MHz)

0.05
0.03

Volume Resistivity

1×10¹¹ Ω·cm
1×10¹³ Ω·cm

Surface Resistivity

1×10¹⁰ Ω
1×10¹² Ω

Comparative Tracking Index (CTI)

150 V
600 V

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

UV / Weathering Resistance

40 / 100
45 / 100

Same in both: Corrosion Resistance 70 / 100

Manufacturability

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

Machinability

70 / 100
30 / 100

Polishability

40 / 100
20 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

78 MJ/kg33,534 BTU/lb
100 MJ/kg42,992 BTU/lb

Embodied Carbon (primary production)

4.5 kg CO₂/kg
6 kg CO₂/kg

Embodied Water

250 L/kg30 gal/lb
200 L/kg24 gal/lb

Same in both: Typical Recycled Content 0%

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

56 kN·m/kg
123 kN·m/kg

Specific Stiffness (E / density)

5.1 MN·m/kg
9.7 MN·m/kg

Thermal Diffusivity

0.2 mm²/s
0.1 mm²/s

Same in both: Thermal Shock Resistance Index 0

Strength versus weight

Yield strength against density for every composite grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.

1101001,000510Density (g/cm³)Yield strength (MPa) — log scale

Manufacturing and finishing

CapabilityCG-9
Default condition——
Relative cost$$$ Premium$$$$ High
Min. machined wall——
Best machined surface——

C vs G-9 — frequently asked

Is G-9 stronger than C?

Yes. G-9 has a typical tensile strength of 240 MPa (34.8 ksi) against 76 MPa (11 ksi) for C — about 3.2 times as much.

Which is cheaper, C or G-9?

C is the lower-cost material: it sits in the premium tier ($$$) while G-9 is high ($$$$). 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, C or G-9?

C. Its machinability rates very good (70/100) against poor (30/100) for G-9.

Ready to make it?

Upload a CAD file and FabDigit prices the part in C and G-9 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.