FabDigit

Gray Iron vs Ductile Iron and 2 more: properties

Gray IronDuctile Iron10061008

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

103 GPa14.9 Msi
169 GPa24.5 Msi
205 GPa29.7 Msi
200 GPa29 Msi

Shear Modulus

41 GPa5.9 Msi
65 GPa9.4 Msi
80 GPa11.6 Msi
80 GPa11.6 Msi

Bulk Modulus

72 GPa10.4 Msi
130 GPa18.9 Msi
160 GPa23.2 Msi
160 GPa23.2 Msi

Poisson's Ratio

0.26
0.28
0.29
0.29

Tensile Strength (Ultimate)

220 MPa31.9 ksi
480 MPa69.6 ksi
300 MPa43.5 ksi
300 MPa43.5 ksi

Yield Strength (0.2% offset)

165 MPa23.9 ksi
340 MPa49.3 ksi
170 MPa24.7 ksi
175 MPa25.4 ksi

Elongation at Break

0.5%
14%
30%
30%

Reduction in Area

0%
12%
55%
55%

Compressive Strength

750 MPa109 ksi
700 MPa102 ksi

Shear Strength

275 MPa39.9 ksi
430 MPa62.4 ksi
200 MPa29 ksi
185 MPa26.8 ksi

Fatigue Strength (Endurance Limit)

100 MPa14.5 ksi
230 MPa33.4 ksi
150 MPa21.8 ksi
150 MPa21.8 ksi

Fracture Toughness (K_IC)

15 MPa·√m13.7 ksi·√in
42 MPa·√m38.2 ksi·√in
130 MPa·√m118 ksi·√in

Charpy V-Notch Impact (RT)

3 J2.2 ft·lbf
10 J7.4 ft·lbf
120 J88.5 ft·lbf
90 J66.4 ft·lbf

Hardness, Brinell

187 HB
187 HB
86 HB
86 HB

Hardness, Rockwell B

90 HRB
90 HRB
41 HRB
45 HRB

Hardness, Vickers

195 HV
90 HV

Physical

Density and transition temperatures.

Density

7.15 g/cm³0.26 lb/in³
7.1 g/cm³0.26 lb/in³
7.87 g/cm³0.28 lb/in³
7.87 g/cm³0.28 lb/in³

Melting Point (Solidus)

1,150°C2,102 °F
1,150°C2,102 °F
1,515°C2,759 °F
1,495°C2,723 °F

Liquidus Temperature

1,200°C2,192 °F
1,175°C2,147 °F
1,535°C2,795 °F
1,530°C2,786 °F

Thermal

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

Thermal Conductivity

46 W/m·K26.6 BTU/hr·ft·°F
33 W/m·K19.1 BTU/hr·ft·°F
65 W/m·K37.6 BTU/hr·ft·°F
60 W/m·K34.7 BTU/hr·ft·°F

Specific Heat Capacity

460 J/kg·K0.11 BTU/lb·°F
460 J/kg·K0.11 BTU/lb·°F
481 J/kg·K0.11 BTU/lb·°F
481 J/kg·K0.11 BTU/lb·°F

Thermal Expansion (CTE, 20–100 °C)

11.5 µm/m·K6.4 µin/in·°F
12 µm/m·K6.7 µin/in·°F
12 µm/m·K6.7 µin/in·°F
12.2 µm/m·K6.8 µin/in·°F

Latent Heat of Fusion

220 J/g94.6 BTU/lb
220 J/g94.6 BTU/lb
247 J/g106 BTU/lb
247 J/g106 BTU/lb

Max Service Temperature (continuous)

400°C752 °F
400°C752 °F
400°C752 °F
425°C797 °F

Min Service Temperature

-30°C-22 °F
-40°C-40 °F
-30°C-22 °F
-30°C-22 °F

Electrical

Conductivity and insulation.

Electrical Conductivity

1.7 % IACS
3.1 % IACS
12 % IACS
11.5 % IACS

Electrical Resistivity

1×10⁻⁶ Ω·m39.4 µΩ·in
5.6×10⁻⁷ Ω·m22 µΩ·in
1.43×10⁻⁷ Ω·m5.63 µΩ·in
1.5×10⁻⁷ Ω·m5.91 µΩ·in

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Galvanic Potential (seawater, vs SCE)

-0.61 V
-0.61 V
-0.65 V
-0.65 V

Corrosion Resistance

18 / 100
16 / 100
10 / 100
10 / 100

Manufacturability

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

Machinability

85 / 100
68 / 100
45 / 100
48 / 100

Machinability Rating (AISI 1212 = 100 %)

80%
70%
50%
45%

Weldability

25 / 100
35 / 100
97 / 100
95 / 100

Formability (cold)

3 / 100
8 / 100
95 / 100
85 / 100

Castability

95 / 100
88 / 100
35 / 100

Brazeability / Solderability

50 / 100
40 / 100
80 / 100
80 / 100

Polishability

35 / 100
55 / 100
45 / 100
50 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

18 MJ/kg7,739 BTU/lb
21 MJ/kg9,028 BTU/lb
25 MJ/kg10,748 BTU/lb
25 MJ/kg10,748 BTU/lb

Embodied Carbon (primary production)

1.5 kg CO₂/kg
1.9 kg CO₂/kg
2.1 kg CO₂/kg
1.9 kg CO₂/kg

Embodied Water

40 L/kg4.8 gal/lb
40 L/kg4.8 gal/lb
55 L/kg6.6 gal/lb
40 L/kg4.8 gal/lb

Typical Recycled Content

90%
85%
28%
25%

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

31 kN·m/kg
68 kN·m/kg
38 kN·m/kg
38 kN·m/kg

Specific Stiffness (E / density)

14.4 MN·m/kg
23.8 MN·m/kg
26 MN·m/kg
25.4 MN·m/kg

Modulus of Resilience

132 kJ/m³
342 kJ/m³
70 kJ/m³
77 kJ/m³

Thermal Diffusivity

14 mm²/s
10.1 mm²/s
17.2 mm²/s
15.9 mm²/s

Thermal Shock Resistance Index

9
8
8
7

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 scale10061008Ductile IronGray Iron

Manufacturing and finishing

CapabilityGray IronDuctile Iron10061008
CNC machiningYesYes
Casting & forgingYesYes
Sheet metalYesYes
Default conditionAs CastAs CastHRHR
Relative cost$$ Standard$$ Standard$ Budget$ Budget
Min. machined wall0.8 mm0.8 mm
Best machined surfaceRa 1.6 µmRa 1.6 µm
AlCrNYesYes
AlTiNYesYes
CVD Al2O3YesYes
CVD TiCNYesYes
CVD TiNYesYes
CrNYesYes
DLCYesYes
HVOF CoatingYesYes
MoS2YesYes
Multilayer CVDYesYes
TiAlNYesYes
TiB2YesYes
TiCNYesYes
TiNYesYes
WC/CYesYes
ZrNYesYes

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.

Ready to make it?

Upload a CAD file and FabDigit prices the part in Gray Iron and Ductile Iron 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.