Precious Metal Silver 999-H08
Supply condition
also Fine Silver, Pure Silver
H08 = spring hard
Heavily drawn fine-silver wire/strip for springy contacts; near-zero remaining ductility, must be formed with generous radii.
Values for the H08 condition
Other Silver 999 tempers and conditions
Silver 999 is listed in 7 conditions; see the grade overview at Silver 999.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As fabricated | Casting grain/shot and lost-wax or ingot castings; coarse grain and possible gas porosity give lower strength than wrought sheet. | 40 | 125 | 30 | 22 HB | 104 % IACS |
ODefault Annealed | Default stock condition for jewellery sheet/wire, deep forming, chasing, bezel work and electrical contacts requiring maximum conductivity and ductility. | 55 | 140 | 48 | 25 HB | 106 % IACS |
Eighth Hard | Fine silver (99.9 % Ag) lightly cold-worked to roughly 1/8-hard temper — slightly stiffer than annealed strip while retaining near-full ductility and >100 % IACS conductivity for contacts and formed parts. | 95 | 175 | 32 | 38 HB | 104 % IACS |
Quarter hard | Light cold work when soft sheet is too floppy but bending and raising must still be easy. | 130 | 180 | 25 | 50 HB | 105 % IACS |
Half hard | Most common non-soft jewellery/technical temper: keeps shape in rings, findings and stampings while still bending without cracking. | 170 | 215 | 12 | 62 HB | 104 % IACS |
Full hard | Hard-drawn wire and hard strip for springy findings, contact wire and applications needing maximum strength without alloying. | 220 | 265 | 5 | 75 HB | 103 % IACS |
H08This page Spring hard | Heavily drawn fine-silver wire/strip for springy contacts; near-zero remaining ductility, must be formed with generous radii. | 265 | 305 | 3 | 85 HB | 102 % IACS |
What is Silver 999-H08?
Silver 999-H08 is Silver 999 supplied in the H08 condition — heavily drawn fine-silver wire/strip for springy contacts; near-zero remaining ductility, must be formed with generous radii. Silver 999-H08 has a yield strength of 265 MPa (38.4 ksi) and a tensile strength of 305 MPa (44.2 ksi) — stronger than 88% of precious metal grades. Elongation at break is 3% and the elastic modulus is 77 GPa (11.2 Msi). Silver 999-H08 has a density of 10.49 g/cm³ (0.379 lb/in³), heavier than 55% of precious metal grades. It melts at 962°C (1,763 °F). O is the default condition FabDigit quotes; H08 is available on request or by drawing note.
Advantages
- Conducts heat well — 415 W/m·K (239.8 BTU/hr·ft·°F), better than 98% of precious metal grades
- High electrical conductivity — 102 % IACS, better than 98% of precious metal grades
- Polishes to a fine finish — 98/100, better than 98% of precious metal grades
- High strength — 265 MPa (38.4 ksi), better than 88% of precious metal grades
Limitations
- Limited service temperature — 100°C (212 °F), worse than 100% of precious metal grades
- Limited ductility — 3%, worse than 95% of precious metal grades
- Low stiffness — 77 GPa (11.2 Msi), worse than 93% of precious metal grades
- Limited formability — 35/100, worse than 92% of precious metal grades
Silver 999-H08 properties
Typical room-temperature values for Silver 999-H08; 19 are specific to this condition. Other listed values are Silver 999 reference data and may not represent this condition. Bars are the position among precious metal grades.
Physical3
Silver 999-H08 has a density of 10.49 g/cm³ (0.379 lb/in³), heavier than 55% of precious metal grades. It melts at 962°C (1,763 °F).
Mechanical12
Silver 999-H08 has a yield strength of 265 MPa (38.4 ksi) and a tensile strength of 305 MPa (44.2 ksi) — stronger than 88% of precious metal grades. Elongation at break is 3% and the elastic modulus is 77 GPa (11.2 Msi).
Thermal6
Silver 999-H08 is rated for continuous service to 100°C (212 °F). It conducts heat at 415 W/m·K (239.8 BTU/hr·ft·°F), better than 98% of precious metal grades. Thermal expansion is 19.6 µm/m·K (10.9 µin/in·°F).
Electrical3
Silver 999-H08 conducts electricity at 102 % IACS, better than 98% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is very good (80/100), worse than 52% of precious metal grades.
Sustainability4
Producing a kilogram of Silver 999-H08 takes about 1,550 MJ of energy and emits 96 kg of CO₂ — more than 55% of precious metal grades. Typical recycled content is 30%.
Manufacturability8
Silver 999-H08's machinability is fair (52/100, better than 78% of precious metal grades); weldability fair (45/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Silver 999-H08
Is Silver 999 easy to machine?
Very gummy and prone to smearing — use sharp polished high-rake carbide/HSS tools, high speed, light positive-rake cuts and generous lubrication; collect all chips for refining.
Can Silver 999 be welded?
Best joined by laser or resistance welding, or by silver brazing/soldering; the extreme thermal conductivity makes conventional arc welding wasteful and oxygen pickup causes porosity.
Can Silver 999 be formed, bent or molded?
Outstanding cold formability — deep drawing, raising, rolling to foil and drawing to fine wire; interanneal at 550–650 °C (quench or air cool) to restore dead-soft temper.
What surface finishes work on Silver 999?
Polishes to a mirror finish easily; protect against H2S tarnish with lacquer, anti-tarnish coatings or rhodium plating, and avoid pickling in sulfur-bearing media.
Silver 999 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 |
|---|---|---|
| Cuprincipal residual | ≤ 0.08 | 0.03 |
| Pb | ≤ 0.03 | |
| Fe | ≤ 0 | |
| Bi | ≤ 0 | |
| Se+Te | ≤ 0 | |
| total impuritiesper ASTM B413 / GB/T 4135 grade IC-Ag99.90 | ≤ 0.1 | 0.05 |
| Ag999 fineness minimum; 99.99 (4N) grades also traded | ≥ 99.9 (balance) |
Silver 999-H08 — frequently asked
What is Silver 999-H08 used for?
Silver 999-H08 is typically used for electrical contacts and contact rivets, solar cell busbars and contacts, bullion bars, brazing filler and conductive paste feedstock, RF plating and waveguide liners and thermal interface and bonding foil. In short: pure fine silver.
What is the yield strength of Silver 999-H08?
Silver 999-H08 has a typical yield strength of 265 MPa (38.4 ksi) and a tensile strength of 305 MPa (44.2 ksi) — stronger than 88% of precious metal grades. Strength varies by condition: see the 7 listed tempers.
Is Silver 999-H08 easy to machine?
Reasonably — machinability is rated fair (52/100, better than 78% of precious metal grades). Very gummy and prone to smearing — use sharp polished high-rake carbide/HSS tools, high speed, light positive-rake cuts and generous lubrication; collect all chips for refining.
Can Silver 999-H08 be welded?
With care — weldability is rated fair (45/100). Best joined by laser or resistance welding, or by silver brazing/soldering; the extreme thermal conductivity makes conventional arc welding wasteful and oxygen pickup causes porosity.
What surface finishes work on Silver 999-H08?
Polishes to a mirror finish easily; protect against H2S tarnish with lacquer, anti-tarnish coatings or rhodium plating, and avoid pickling in sulfur-bearing media.
Can Silver 999-H08 be formed, bent or molded?
Outstanding cold formability — deep drawing, raising, rolling to foil and drawing to fine wire; interanneal at 550–650 °C (quench or air cool) to restore dead-soft temper.
What is the maximum service temperature of Silver 999-H08?
Silver 999-H08 is rated for continuous use to about 100°C (212 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Silver 999-O and Silver 999-H08?
O is the default condition — default stock condition for jewellery sheet/wire, deep forming, chasing, bezel work and electrical contacts requiring maximum conductivity and ductility. H08: heavily drawn fine-silver wire/strip for springy contacts; near-zero remaining ductility, must be formed with generous radii. Yield strength is 55 MPa in O versus 265 MPa in H08.
Sources
- ASTM B413 — Standard Specification for Refined Silver — ASTM International (2019)
- GB/T 4135 — (Silver ingot) — SAC / (2016)
- ASTM B601 — Temper designations for copper and copper alloy wrought products (temper code convention) — ASTM International (2019)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (pure silver) — ASM International (1990)
- ASM Specialty Handbook — Precious Metals and Their Alloys section — ASM International (1998)
- CRC Handbook of Chemistry and Physics — physical properties of silver — CRC Press (2020)
- Fine silver (999) sheet, wire and grain technical data — precious-metal fabricators (e.g. Hoover & Strong / Umicore) (2023)
- (SMM) / LBMA silver price — SMM / LBMA (2026)
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.