Precious Metal Britannia Silver (958)-O (Annealed)
Temper · default condition
BS 958 Silver
Standard stocked condition for raising, chasing, spinning and deep forming.
Values for the O condition
Other Britannia Silver (958) tempers and conditions
Britannia Silver (958) is listed in 6 conditions; see the grade overview at Britannia Silver (958).
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ODefaultThis page Annealed | Standard stocked condition for raising, chasing, spinning and deep forming. | 60 | 240 | 48 | 47 HB | 92 % IACS |
As fabricated | Choose for cast holloware, hallmarked giftware and one-off sculptural pieces. | 85 | 215 | 22 | 52 HB | 90 % IACS |
Quarter hard | Pick when the part must keep shape during light forming but still bend without cracking. | 200 | 290 | 25 | 66 HB | 91 % IACS |
Half hard | General-purpose stiffened sheet/wire for bezels, settings and flatware blanks. | 260 | 330 | 12 | 85 HB | 90 % IACS |
Full hard | Maximum strength/wear for rims, hinges, clasps and thin structural sections. | 320 | 380 | 5 | 102 HB | 89 % IACS |
Extra hard | For springy wire, pin stems and clasp tongues where deflection recovery matters. | 370 | 420 | 3 | 114 HB | 88 % IACS |
What is Britannia Silver (958)-O?
Britannia Silver (958)-O is Britannia Silver (958) in the O temper — standard stocked condition for raising, chasing, spinning and deep forming. Britannia Silver (958)-O has a yield strength of 60 MPa (8.7 ksi) and a tensile strength of 240 MPa (34.8 ksi) — weaker than 93% of precious metal grades. Elongation at break is 48% and the elastic modulus is 76 GPa (11 Msi). Britannia Silver (958)-O has a density of 10.41 g/cm³ (0.376 lb/in³), heavier than 52% of precious metal grades. It melts at 779°C (1,434 °F).
Advantages
- Ductile — tolerates forming and impact — 48%, better than 100% of precious metal grades
- Conducts heat well — 385 W/m·K (222.4 BTU/hr·ft·°F), better than 97% of precious metal grades
- Forms and bends easily — 98/100, better than 97% of precious metal grades
- High electrical conductivity — 92 % IACS, better than 96% of precious metal grades
- Polishes to a fine finish — 97/100, better than 96% of precious metal grades
Limitations
- Low stiffness — 76 GPa (11 Msi), worse than 96% of precious metal grades
- Low strength — 60 MPa (8.7 ksi), worse than 93% of precious metal grades
- Limited service temperature — 200°C (392 °F), worse than 89% of precious metal grades
Britannia Silver (958)-O properties
Typical room-temperature values for Britannia Silver (958)-O; 11 are specific to this condition. Other listed values are Britannia Silver (958) reference data and may not represent this condition. Bars are the position among precious metal grades.
Physical3
Britannia Silver (958)-O has a density of 10.41 g/cm³ (0.376 lb/in³), heavier than 52% of precious metal grades. It melts at 779°C (1,434 °F).
Mechanical11
Britannia Silver (958)-O has a yield strength of 60 MPa (8.7 ksi) and a tensile strength of 240 MPa (34.8 ksi) — weaker than 93% of precious metal grades. Elongation at break is 48% and the elastic modulus is 76 GPa (11 Msi).
Thermal6
Britannia Silver (958)-O is rated for continuous service to 200°C (392 °F). It conducts heat at 385 W/m·K (222.4 BTU/hr·ft·°F), better than 97% of precious metal grades. Thermal expansion is 19 µm/m·K (10.6 µin/in·°F).
Electrical3
Britannia Silver (958)-O conducts electricity at 92 % IACS, better than 96% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is very good (78/100), worse than 56% of precious metal grades.
Sustainability4
Producing a kilogram of Britannia Silver (958)-O takes about 1,500 MJ of energy and emits 105 kg of CO₂ — more than 51% of precious metal grades. Typical recycled content is 55%.
Manufacturability8
Britannia Silver (958)-O's machinability is fair (45/100, better than 59% of precious metal grades); weldability very good (70/100); formability excellent (98/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Britannia Silver (958)-O
Is Britannia Silver (958) easy to machine?
Very gummy — use sharp polished HSS or uncoated carbide, high rake, high speed, light feed with oil mist; collect all swarf for refining.
Can Britannia Silver (958) be welded?
Laser/PUK spot welding is the norm; the high thermal conductivity makes TIG difficult, and hard silver solders (Ag-Cu-Zn, 700–800 °C) are preferred for joining.
Can Britannia Silver (958) be formed, bent or molded?
Outstanding cold formability when annealed (raising, spinning, die-forming); anneal at 600–650 °C and quench between ~50% reduction steps, and avoid overheating past 780 °C (eutectic incipient melting).
What surface finishes work on Britannia Silver (958)?
Polishes to a mirror easily; less firescale than sterling but still requires pickling or protective flux; commonly rhodium-plated, lacquered or deliberately patinated with liver of sulfur.
Britannia Silver (958) 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 |
|---|---|---|
| Ag958 parts per thousand minimum fineness (UK Britannia standard / ISO 9202) | 95.84 – 96.5 | 95.9 |
| Znoptional deoxidiser in some casting grades | ≤ 0.3 | — |
| Geused in some proprietary firescale-free 958 alloys | ≤ 0.5 | — |
| Sioptional deoxidiser | ≤ 0.05 | — |
| Pbimpurity limit; causes hot shortness | ≤ 0.01 | — |
| Cuprincipal hardener | ≥ 3.3 (balance) | — |
Britannia Silver (958)-O — frequently asked
What is Britannia Silver (958)-O used for?
Britannia Silver (958)-O is typically used for fine hollowware, hallmarked flatware, ecclesiastical silverware and high-end jewelry. In short: softest formable silver standard; more tarnish-resistant than sterling; near-pure silver conductivity.
What is the yield strength of Britannia Silver (958)-O?
Britannia Silver (958)-O has a typical yield strength of 60 MPa (8.7 ksi) and a tensile strength of 240 MPa (34.8 ksi) — weaker than 93% of precious metal grades. Strength varies by condition: see the 6 listed tempers.
Is Britannia Silver (958)-O easy to machine?
Reasonably — machinability is rated fair (45/100, better than 59% of precious metal grades). Very gummy — use sharp polished HSS or uncoated carbide, high rake, high speed, light feed with oil mist; collect all swarf for refining.
Can Britannia Silver (958)-O be welded?
Yes — weldability is rated very good (70/100). Laser/PUK spot welding is the norm; the high thermal conductivity makes TIG difficult, and hard silver solders (Ag-Cu-Zn, 700–800 °C) are preferred for joining.
What surface finishes work on Britannia Silver (958)-O?
Polishes to a mirror easily; less firescale than sterling but still requires pickling or protective flux; commonly rhodium-plated, lacquered or deliberately patinated with liver of sulfur.
Can Britannia Silver (958)-O be formed, bent or molded?
Outstanding cold formability when annealed (raising, spinning, die-forming); anneal at 600–650 °C and quench between ~50% reduction steps, and avoid overheating past 780 °C (eutectic incipient melting).
What is the maximum service temperature of Britannia Silver (958)-O?
Britannia Silver (958)-O is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Britannia Silver (958)-O and Britannia Silver (958)-H06?
O is the default condition — standard stocked condition for raising, chasing, spinning and deep forming. H06: for springy wire, pin stems and clasp tongues where deflection recovery matters. Yield strength is 60 MPa in O versus 370 MPa in H06.
Sources
- ISO 9202 Jewellery — Fineness of precious metal alloys — ISO (2019)
- Hallmarking Act 1973 (Britannia standard 958) — UK Assay Offices / British Hallmarking Council (1973)
- ASM Specialty Handbook: Precious Metals & Their Alloys / ASM Handbook Vol.2 — ASM International (1990)
- ASM Handbook Vol.3: Alloy Phase Diagrams (Ag-Cu system) — ASM International (1992)
- Santa Fe Symposium on Jewelry Manufacturing Technology — silver alloy property compilations — Met-Chem Research (2018)
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.