Precious Metal 9K-H04
Supply condition
GB Au375 · ISO 9202
H04 = full hard
Pick for earring posts, clasp springs, pin stems and thin wire needing maximum stiffness and wear resistance.
Values for the H04 condition
Other 9K tempers and conditions
9K is listed in 8 conditions; see the grade overview at 9K.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Condition of lost-wax cast rings and pendants straight from the flask, before work hardening or ageing. | 200 | 330 | 18 | 124 HB | 16 % IACS |
ANNDefault Annealed | Pick for forming, stone setting, bending and chain assembly where maximum ductility is needed. | 210 | 360 | 35 | 115 HB | 17 % IACS |
9K Yellow | Standard yellow colour composition — the default 9K sold for chain, sheet and casting grain. | 210 | 360 | 35 | 115 HB | 17 % IACS |
9K Red / Rose | Copper-rich colour variant for rose-tone jewellery; hardest 9K colour but most tarnish-prone and hot-short. | 250 | 400 | 28 | 133 HB | 20 % IACS |
9K White | Choose for white-metal look at lowest gold cost; harder and stiffer, but check EU nickel-release limits. | 300 | 480 | 22 | 165 HV | 60 W/m·K |
Half hard | General-purpose stock temper for wire, sheet and tube that must hold shape yet still bend. | 400 | 520 | 10 | 157 HB | 16 % IACS |
Age hardened | Optional low-temperature ageing of Au-Cu-Ag compositions to raise hardness and wear life of set pieces. | 480 | 600 | 6 | 190 HB | 19 % IACS |
H04This page Full hard | Pick for earring posts, clasp springs, pin stems and thin wire needing maximum stiffness and wear resistance. | 560 | 660 | 3 | 198 HB | 15.5 % IACS |
What is 9K-H04?
9K-H04 is 9K supplied in the H04 condition — pick for earring posts, clasp springs, pin stems and thin wire needing maximum stiffness and wear resistance. 9K-H04 has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 660 MPa (95.7 ksi) — stronger than 97% of precious metal grades. Elongation at break is 3% and the elastic modulus is 92 GPa (13.3 Msi). 9K-H04 has a density of 11.3 g/cm³ (0.408 lb/in³), heavier than 59% of precious metal grades. It melts at 880°C (1,616 °F). ANN is the default condition FabDigit quotes; H04 is available on request or by drawing note.
Advantages
- Easy to machine — 72/100, better than 101% of precious metal grades
- High strength — 560 MPa (81.2 ksi), better than 97% of precious metal grades
Limitations
- Limited service temperature — 175°C (347 °F), worse than 100% of precious metal grades
- Needs corrosion protection — 53/100, worse than 98% of precious metal grades
- Limited ductility — 3%, worse than 95% of precious metal grades
- Limited formability — 25/100, worse than 95% of precious metal grades
9K-H04 properties
Typical room-temperature values for 9K-H04; 19 are specific to this condition. Other listed values are 9K reference data and may not represent this condition. Bars are the position among precious metal grades.
Physical3
9K-H04 has a density of 11.3 g/cm³ (0.408 lb/in³), heavier than 59% of precious metal grades. It melts at 880°C (1,616 °F).
Mechanical13
9K-H04 has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 660 MPa (95.7 ksi) — stronger than 97% of precious metal grades. Elongation at break is 3% and the elastic modulus is 92 GPa (13.3 Msi).
Thermal6
9K-H04 is rated for continuous service to 175°C (347 °F). It conducts heat at 103 W/m·K (59.5 BTU/hr·ft·°F), better than 59% of precious metal grades. Thermal expansion is 17.5 µm/m·K (9.72 µin/in·°F).
Electrical3
9K-H04 conducts electricity at 15.5 % IACS, worse than 62% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is fair (53/100), worse than 98% of precious metal grades.
Sustainability4
Producing a kilogram of 9K-H04 takes about 95,000 MJ of energy and emits 6,500 kg of CO₂ — more than 68% of precious metal grades. Typical recycled content is 35%.
Manufacturability8
9K-H04's machinability is very good (72/100, better than 101% of precious metal grades); weldability good (65/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 9K-H04
Is 9K easy to machine?
Turns and mills cleanly with sharp carbide or HSS tools and light cuts; work in the half-hard temper to avoid smearing and always collect swarf for refining.
Can 9K be welded?
Laser and PUK micro-welding with matching 9K filler are standard; torch work needs matching 9K easy/medium/hard solders and borax-type flux to avoid firescale from the high copper.
Can 9K be formed, bent or molded?
Rolls, draws and stamps well when annealed at 600–650 °C with rapid quench; anneal every 40–50 % reduction because the copper-rich matrix work-hardens quickly.
What surface finishes work on 9K?
Polishes to a high lustre with tripoli then rouge; white 9K is normally rhodium plated, and copper-rich yellow/red benefits from a protective lacquer or e-coat to slow tarnish.
9K 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 |
|---|---|---|
| Au375‰ minimum fineness per ISO 9202 / UK Hallmarking Act | 37.5 – 38.5 | 37.6 |
| Agcolour and ductility control (yellow grades) | 4 – 15 | 10 |
| Zndeoxidiser, lowers melting range | 3 – 12 | 7.5 |
| Niwhite grades only; must meet EN 1811 nickel-release limits | 0 – 15 | — |
| Pdnickel-free white grades | 0 – 10 | — |
| Cubalance, typically 40–55 % in yellow/red grades | balance | — |
9K-H04 — frequently asked
What is 9K-H04 used for?
9K-H04 is typically used for UK and European mass-market rings, chains and bracelets, budget engagement and eternity rings, stamped findings and settings, cast pendants and charms and earrings and studs. In short: lowest legal UK karat; hardest standard karat; most affordable karat gold.
What is the yield strength of 9K-H04?
9K-H04 has a typical yield strength of 560 MPa (81.2 ksi) and a tensile strength of 660 MPa (95.7 ksi) — stronger than 97% of precious metal grades. Strength varies by condition: see the 8 listed tempers.
Is 9K-H04 easy to machine?
Yes — machinability is rated very good (72/100, better than 101% of precious metal grades). Turns and mills cleanly with sharp carbide or HSS tools and light cuts; work in the half-hard temper to avoid smearing and always collect swarf for refining.
Can 9K-H04 be welded?
Yes — weldability is rated good (65/100). Laser and PUK micro-welding with matching 9K filler are standard; torch work needs matching 9K easy/medium/hard solders and borax-type flux to avoid firescale from the high copper.
What surface finishes work on 9K-H04?
Polishes to a high lustre with tripoli then rouge; white 9K is normally rhodium plated, and copper-rich yellow/red benefits from a protective lacquer or e-coat to slow tarnish.
Can 9K-H04 be formed, bent or molded?
Rolls, draws and stamps well when annealed at 600–650 °C with rapid quench; anneal every 40–50 % reduction because the copper-rich matrix work-hardens quickly.
What is the maximum service temperature of 9K-H04?
9K-H04 is rated for continuous use to about 175°C (347 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 9K-ANN and 9K-H04?
ANN is the default condition — pick for forming, stone setting, bending and chain assembly where maximum ductility is needed. H04: pick for earring posts, clasp springs, pin stems and thin wire needing maximum stiffness and wear resistance. Yield strength is 210 MPa in ANN versus 560 MPa in H04.
Sources
- ISO 9202 Jewellery — Fineness of precious metal alloys — ISO (2019)
- Metallurgy of Gold Jewellery Alloys (Grimwade) — World Gold Council (2009)
- ASM Handbook Vol. 2 — Precious Metals and Their Alloys — ASM International (1990)
- Gold Bulletin — mechanical properties of carat golds — Springer / World Gold Council (2005)
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.