Precious Metal Gold 18K-O (Annealed)
Temper · default condition
Default stocked condition for sheet, wire and tube that will be bent, stamped, drawn or stone-set.
Values for the O condition
Other Gold 18K tempers and conditions
Gold 18K is listed in 6 conditions; see the grade overview at Gold 18K.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ODefaultThis page Annealed | Default stocked condition for sheet, wire and tube that will be bent, stamped, drawn or stone-set. | 200 | 450 | 40 | 140 HB | — |
investment / centrifugal cast, no post heat treatment | Standard state of cast jewellery bodies and hollowware; coarse dendritic grain gives lower ductility than annealed wrought stock. | 230 | 420 | 22 | 145 HB | 185 W/m·K |
Half hard | Compromise temper for sheet and wire that must still take moderate bending but resist deformation in service. | 500 | 640 | 10 | 14 HRC | 15 % IACS |
cold worked + low-temperature relief (250–300 °C) | Use after cold forming or machining to cut residual stress and stress-corrosion risk while keeping most of the work-hardened strength. | 580 | 700 | 9 | 17 HRC | 15 % IACS |
hard (≈50–70 % reduction) | Choose for springy clasps, pins, wire and thin sections needing maximum strength and dent resistance. | 660 | 780 | 4 | 220 HB | 15 % IACS |
order-hardened (quench from ~650 °C, age 250–300 °C) | Applies to Cu-rich 18K yellow/rose (AuCu ordering) and to Ni/Pd 18K white: raises hardness of finished, non-deformable parts such as watch cases and prong settings. | 680 | 800 | 6 | 22 HRC | 19 % IACS |
What is Gold 18K-O?
Gold 18K-O is Gold 18K in the O temper — default stocked condition for sheet, wire and tube that will be bent, stamped, drawn or stone-set. Gold 18K-O has a yield strength of 200 MPa (29 ksi) and a tensile strength of 450 MPa (65.3 ksi) — stronger than 51% of precious metal grades. Elongation at break is 40% and the elastic modulus is 78 GPa (11.3 Msi). Gold 18K-O has a density of 15.5 g/cm³ (0.56 lb/in³), heavier than 77% of precious metal grades. It melts at 895°C (1,643 °F).
Advantages
- Polishes to a fine finish — 98/100, better than 98% of precious metal grades
- Easy to machine — 60/100, better than 97% of precious metal grades
- Readily welded — 85/100, better than 93% of precious metal grades
- Ductile — tolerates forming and impact — 40%, better than 92% of precious metal grades
- Forms and bends easily — 95/100, better than 91% of precious metal grades
Limitations
- Low stiffness — 78 GPa (11.3 Msi), worse than 90% of precious metal grades
- Heavy — 15.5 g/cm³ (0.56 lb/in³), worse than 77% of precious metal grades
Gold 18K-O properties
Typical room-temperature values for Gold 18K-O; 10 are specific to this condition. Other listed values are Gold 18K reference data and may not represent this condition. Bars are the position among precious metal grades.
Physical3
Gold 18K-O has a density of 15.5 g/cm³ (0.56 lb/in³), heavier than 77% of precious metal grades. It melts at 895°C (1,643 °F).
Mechanical12
Gold 18K-O has a yield strength of 200 MPa (29 ksi) and a tensile strength of 450 MPa (65.3 ksi) — stronger than 51% of precious metal grades. Elongation at break is 40% and the elastic modulus is 78 GPa (11.3 Msi).
Thermal6
Gold 18K-O is rated for continuous service to 400°C (752 °F). It conducts heat at 190 W/m·K (109.8 BTU/hr·ft·°F), better than 68% of precious metal grades. Thermal expansion is 16 µm/m·K (8.89 µin/in·°F).
Electrical3
Gold 18K-O conducts electricity at 16 % IACS, worse than 60% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (93/100), better than 77% of precious metal grades.
Sustainability4
Producing a kilogram of Gold 18K-O takes about 180,000 MJ of energy and emits 11,000 kg of CO₂ — more than 77% of precious metal grades. Typical recycled content is 30%.
Manufacturability8
Gold 18K-O's machinability is good (60/100, better than 97% of precious metal grades); weldability excellent (85/100); formability excellent (95/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Gold 18K-O
Is Gold 18K easy to machine?
Turns and engraves beautifully with sharp PCD/carbide tools, high speed, low feed and light cuts; annealed material is gummy, so half-hard stock and swarf recovery for refining are standard practice.
Can Gold 18K be welded?
Excellent with pulsed Nd:YAG/fibre laser and PUK micro-TIG using matching 18K filler; oxyacetylene brazing with graded gold solders is routine, but avoid overheating Zn-bearing casting alloys.
Can Gold 18K be formed, bent or molded?
In the annealed temper it rolls, draws, spins and stamps readily with interstage anneals at 650–700 °C; investment casting at 950–1050 °C mould temperature is the dominant route, plus SLM for complex parts.
What surface finishes work on Gold 18K?
Polishes to a mirror with tripoli/rouge and can be electroformed, rhodium- or Pd-plated (whites) and PVD coated; no anodising — ultrasonic and steam cleaning are the usual final steps.
Gold 18K chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Au750 ‰ legal fineness minimum; refiners aim 75.2–75.5 % to stay above assay tolerance | 75 – 75.8 | 75 |
| Agyellow 18K; near zero in Ni/Pd whites | 0 – 16 | 12.5 |
| Zndeoxidiser / colour and flow modifier in casting alloys | 0 – 4 | 0.5 |
| Ni18K white (Au-Ni-Cu-Zn) only; restricted by EU nickel-release rules | 0 – 13 | 0 |
| Pdnickel-free 18K white (Au-Pd-Ag-Cu) | 0 – 15 | 0 |
| Co+Ir+Ru+Sigrain refiners / deoxidisers in casting and 3D-printing powders | 0 – 0.3 | 0.05 |
| Cubalance of the 250 ‰ base metal; up to ~25 % in 18K red/rose | ≥ 0 (balance) |
Gold 18K-O — frequently asked
What is Gold 18K-O used for?
Gold 18K-O is typically used for fine jewelry rings and bracelets, watch cases and bezels, dental crowns and inlays, decorative electronics trim, engraved medallions and awards and clasps, cufflinks and findings. In short: premium 18K jewelry gold.
What is the yield strength of Gold 18K-O?
Gold 18K-O has a typical yield strength of 200 MPa (29 ksi) and a tensile strength of 450 MPa (65.3 ksi) — stronger than 51% of precious metal grades. Strength varies by condition: see the 6 listed tempers.
Is Gold 18K-O easy to machine?
Reasonably — machinability is rated good (60/100, better than 97% of precious metal grades). Turns and engraves beautifully with sharp PCD/carbide tools, high speed, low feed and light cuts; annealed material is gummy, so half-hard stock and swarf recovery for refining are standard practice.
Can Gold 18K-O be welded?
Yes — weldability is rated excellent (85/100). Excellent with pulsed Nd:YAG/fibre laser and PUK micro-TIG using matching 18K filler; oxyacetylene brazing with graded gold solders is routine, but avoid overheating Zn-bearing casting alloys.
What surface finishes work on Gold 18K-O?
Polishes to a mirror with tripoli/rouge and can be electroformed, rhodium- or Pd-plated (whites) and PVD coated; no anodising — ultrasonic and steam cleaning are the usual final steps.
Can Gold 18K-O be formed, bent or molded?
In the annealed temper it rolls, draws, spins and stamps readily with interstage anneals at 650–700 °C; investment casting at 950–1050 °C mould temperature is the dominant route, plus SLM for complex parts.
What is the maximum service temperature of Gold 18K-O?
Gold 18K-O is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- The Metallurgy of Carat Gold Alloys / Gold Bulletin property compilations — World Gold Council / Springer (2004)
- ASM Handbook Vol. 2 — Properties of Nonferrous Alloys (Precious Metals) — ASM International (1990)
- ISO 9202 Jewellery — Fineness of precious metal alloys — ISO (2019)
- 18K gold casting alloys and SLM powder data — Cooksongold / Legor Group / Hoover & Strong (2023)
- CES EduPack precious-metal eco-property records (scaled to 750 ‰) — Ansys Granta (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.