Precious Metal Gold 18K
18K gold is a 750 ‰ (75 wt %) gold alloy, most commonly balanced with silver and copper (yellow), or with palladium/nickel and zinc (white) and copper-rich (rose).
Reference datasheet — Gold 18K is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the O condition
Gold 18K tempers and conditions
Gold 18K is supplied in 6 conditions, soft to hard. O is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ODefault 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?
18K gold is a 750 ‰ (75 wt %) gold alloy, most commonly balanced with silver and copper (yellow), or with palladium/nickel and zinc (white) and copper-rich (rose). It is chosen for jewellery, watch cases, dental and decorative electronics work because it keeps gold's tarnish resistance and colour while the 25 % base-metal addition raises strength and hardness far above pure gold and allows cold working, casting, laser welding and additive manufacturing. Limits are the very high material cost, low stiffness and creep resistance for a metal, softening above ~300 °C, and the copper/silver content which permits sulfide tarnish, stress-corrosion in chloride/ammonia environments and (for Ni-white grades) skin sensitisation. Gold 18K 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). Gold 18K 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).
What is Gold 18K used for?
- Fine jewelry rings and bracelets
- Watch cases and bezels
- Dental crowns and inlays
- Decorative electronics trim
- Engraved medallions and awards
- Clasps, cufflinks and findings
- Writing instrument nibs and trim
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 properties
Typical room-temperature values for Gold 18K-O; bars are the position among precious metal grades.
Physical3
Gold 18K 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 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 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 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 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'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. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the precious metal family
Yield strength against density for every precious metal grade FabDigit runs. Gold 18K is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Gold 18K
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.
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) |
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.
How much does Gold 18K cost?
Gold 18K is a specialty-cost precious metal ($$$$$), pricier than about 100% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Gold 18K — frequently asked
What is Gold 18K used for?
Gold 18K 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?
Gold 18K 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 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 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?
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 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?
Gold 18K 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.
How much does Gold 18K cost?
Gold 18K is a specialty-cost precious metal ($$$$$), pricier than about 100% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.