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Precious Metal 18K vs 24K

Precious Metal · grade comparison

Precious Metal 18K and 24K are both precious metal grades. 18K is the stronger of the two: yield strength 240 MPa (34.8 ksi) against 30 MPa (4.35 ksi) for 24K, about 8.0 times as much; tensile strength follows at 450 MPa (65.3 ksi) vs 125 MPa (18.1 ksi). In exchange, 24K is the more ductile: elongation 45% versus 38% for 18K, and 18K is harder (143 HB vs 25 HB). 18K is lighter (15.5 g/cm³ vs 19.32 g/cm³ for 24K) and 24K runs hotter in service (600°C vs 300°C continuous). On the shop floor, 18K machines more easily (fair vs poor).

18KChoose it when strength drives the design, or when weight is the constraint.

24KChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.

18K vs 24K: properties

18K24K

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

80 GPa11.6 Msi
78 GPa11.3 Msi

Shear Modulus

29 GPa4.2 Msi
27 GPa3.9 Msi

Bulk Modulus

135 GPa19.6 Msi
180 GPa26.1 Msi

Poisson's Ratio

0.4
0.42

Tensile Strength (Ultimate)

450 MPa65.3 ksi
125 MPa18.1 ksi

Yield Strength (0.2% offset)

240 MPa34.8 ksi
30 MPa4.4 ksi

Elongation at Break

38%
45%

Reduction in Area

48%
90%

Compressive Strength

245 MPa35.5 ksi
—

Shear Strength

280 MPa40.6 ksi
90 MPa13.1 ksi

Fatigue Strength (Endurance Limit)

250 MPa36.3 ksi
35 MPa5.1 ksi

Fracture Toughness (K_IC)

50 MPa·√m45.5 ksi·√in
—

Charpy V-Notch Impact (RT)

38 J28 ft·lbf
—

Hardness, Brinell

143 HB
25 HB

Hardness, Rockwell B

80 HRB
—

Hardness, Vickers

150 HV
25 HV

Physical

Density and transition temperatures.

Density

15.5 g/cm³0.56 lb/in³
19.32 g/cm³0.7 lb/in³

Melting Point (Solidus)

885°C1,625 °F
1,064°C1,947 °F

Liquidus Temperature

910°C1,670 °F
1,064°C1,947 °F

Thermal

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

Thermal Conductivity

150 W/m·K86.7 BTU/hr·ft·°F
318 W/m·K184 BTU/hr·ft·°F

Specific Heat Capacity

165 J/kg·K0.04 BTU/lb·°F
129 J/kg·K0.03 BTU/lb·°F

Thermal Expansion (CTE, 20–100 °C)

15.5 µm/m·K8.6 µin/in·°F
14.2 µm/m·K7.9 µin/in·°F

Latent Heat of Fusion

75 J/g32.2 BTU/lb
64 J/g27.4 BTU/lb

Max Service Temperature (continuous)

300°C572 °F
600°C1,112 °F

Min Service Temperature

-200°C-328 °F
-250°C-418 °F

Electrical

Conductivity and insulation.

Electrical Conductivity

16 % IACS
71 % IACS

Electrical Resistivity

1.08×10⁻⁷ Ω·m4.25 µΩ·in
2.44×10⁻⁸ Ω·m0.961 µΩ·in

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Galvanic Potential (seawater, vs SCE)

0.2 V
0.25 V

Corrosion Resistance

93 / 100
100 / 100

Manufacturability

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

Machinability

50 / 100
30 / 100

Machinability Rating (AISI 1212 = 100 %)

45%
25%

Weldability

82 / 100
90 / 100

Formability (cold)

92 / 100
100 / 100

Polishability

98 / 100
90 / 100

Same in both: Castability 85 / 100 · Brazeability / Solderability 95 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

190,000 MJ/kg8.17×10⁷ BTU/lb
250,000 MJ/kg1.07×10⁸ BTU/lb

Embodied Carbon (primary production)

15,000 kg CO₂/kg
20,000 kg CO₂/kg

Embodied Water

200,000 L/kg23,965 gal/lb
150,000 L/kg17,974 gal/lb

Typical Recycled Content

35%
28%

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

29 kN·m/kg
6 kN·m/kg

Specific Stiffness (E / density)

5.2 MN·m/kg
4 MN·m/kg

Modulus of Resilience

360 kJ/m³
6 kJ/m³

Thermal Diffusivity

58.7 mm²/s
127.6 mm²/s

Thermal Shock Resistance Index

54
36

Strength versus weight

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

50100200500101520Density (g/cm³)Yield strength (MPa) — log scale24K18K

Manufacturing and finishing

Capability18K24K
Default condition——
Relative cost$$$$ High$$$$ High
Min. machined wall——
Best machined surface——

18K vs 24K — frequently asked

Is 18K stronger than 24K?

Yes. 18K has a typical yield strength of 240 MPa (34.8 ksi) against 30 MPa (4.35 ksi) for 24K — about 8.0 times as much. Tensile strength is 450 MPa (65.3 ksi) vs 125 MPa (18.1 ksi).

Which is cheaper, 18K or 24K?

Both sit in the same relative cost tier ($$$$, high); the part price will be decided by machining time, tolerance and quantity rather than by the material.

Which is easier to machine, 18K or 24K?

18K. Its machinability rates fair (50/100) against poor (30/100) for 24K; for welding the order is 24K first (excellent, 90/100) then 18K (very good, 82/100).

Ready to make it?

Upload a CAD file and FabDigit prices the part in 18K and 24K 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.