Precious Metal 18K-H04 vs 18K-O
Precious Metal · 18K temper comparison
18K-H04 and 18K-O are two conditions of the same precious metal grade, 18K: H04 (full hard) versus O (annealed). The chemistry is identical, so every difference below comes from the condition. 18K-H04 is the stronger of the two: yield strength 680 MPa (98.6 ksi) against 240 MPa (34.8 ksi) for 18K-O, about 183% more; tensile strength follows at 760 MPa (110 ksi) vs 450 MPa (65.3 ksi). In exchange, 18K-O is the more ductile: elongation 38% versus 3% for 18K-H04, and 18K-H04 is harder (204 HB vs 143 HB). 18K-O runs hotter in service (300°C vs 170°C continuous). On the shop floor, 18K-H04 machines more easily (good vs fair) and 18K-O welds better (82 vs 70 out of 100).
18K-H04Choose it when strength drives the design, or when the part is machined in volume.
18K-OChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
18K-H04 vs 18K-O: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all precious metal grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all precious metal grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Vickers
Same in both: Shear Modulus 29 GPa4.2 Msi · Bulk Modulus 135 GPa19.6 Msi · Poisson's Ratio 0.4
Physical
Density and transition temperatures.
Same in both: Density 15.5 g/cm³0.56 lb/in³ · Melting Point (Solidus) 885°C1,625 °F · Liquidus Temperature 910°C1,670 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Max Service Temperature (continuous)
Same in both: Specific Heat Capacity 165 J/kg·K0.04 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 15.5 µm/m·K8.6 µin/in·°F · Latent Heat of Fusion 75 J/g32.2 BTU/lb · Min Service Temperature -200°C-328 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Same in both: Galvanic Potential (seawater, vs SCE) 0.2 V
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Same in both: Castability 85 / 100 · Brazeability / Solderability 95 / 100 · Polishability 98 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 190,000 MJ/kg8.17×10⁷ BTU/lb · Embodied Carbon (primary production) 15,000 kg CO₂/kg · Embodied Water 200,000 L/kg23,965 gal/lb · Typical Recycled Content 35%
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.
18K-H04 vs 18K-O — frequently asked
Is 18K-H04 stronger than 18K-O?
Yes. 18K-H04 has a typical yield strength of 680 MPa (98.6 ksi) against 240 MPa (34.8 ksi) for 18K-O — about 183% more. Tensile strength is 760 MPa (110 ksi) vs 450 MPa (65.3 ksi).
Which condition does FabDigit quote by default, H04 or O?
O is the default 18K condition in the FabDigit quote flow. The other condition is available on request or by drawing note — specify it in the material field or the part notes and the quote is priced for it.
Which is easier to machine, 18K-H04 or 18K-O?
18K-H04. Its machinability rates good (65/100) against fair (50/100) for 18K-O; for welding the order is 18K-O first (very good, 82/100) then 18K-H04 (very good, 70/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in 18K-H04 and 18K-O 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.