Material Comparison
Compare verified engineering materials side by side with condition-specific mechanical properties.
| Parameter | Britannia Silver 958 | Fine Silver 999 |
|---|---|---|
| Material Family | Silver & Silver Alloys | Silver & Silver Alloys |
| Subfamily | Alloyed Silver | Fine Silver |
| UK-HALLMARK Designation | 958 | 999 |
| ISO Designation | Ag958 | Ag99.9 |
| DIN Designation | Ag958 | Ag99.9 |
| EN Designation | AgCu4.2 | — |
| SPECIFICATION Designation | British Hallmarking Act 1973 Schedule 2 Standards of Fineness | ASTM B742 Standard Specification for Fine Silver Contact Material |
| UNS Designation | — | P07010 |
| ASTM Designation | — | Grade 99.90 |
| W-Nr Designation | — | 2.1211 |
| Element | Britannia Silver 958 | Fine Silver 999 |
|---|---|---|
| Ag (Silver) | ≥ 95.84% | ≥ 99.9% |
| Cu (Copper) | 4 – 4.16% | ≤ 0.08% |
| Fe (Iron) | — | ≤ 0.01% |
| Pb (Lead) | — | ≤ 0.015% |
| Bi (Bismuth) | — | ≤ 0.005% |
| Property | Britannia Silver 958 | Fine Silver 999 |
|---|---|---|
| Density · TYPICAL · 20 °CUnit: g/cm³ | 10.4 g/cm³ | 10.49 g/cm³ |
| Mechanical Parameter | Britannia Silver 958Annealed (Soft) | Fine Silver 999Annealed (Soft) |
|---|---|---|
| Modulus of Elasticity · TYPICALUnit: GPa | 78 GPa | 76 GPa |
| Yield Strength (0.2% Offset) · Strip, Sheet, Wire · Annealed (Soft) · TYPICALUnit: MPa | ≥ 80 MPa | — MPa |
| Yield Strength (0.2% Offset) · Strip, Sheet, Wire, Bar · Annealed (Soft) · TYPICALUnit: MPa | — MPa | ≥ 40 MPa |
| Ultimate Tensile Strength · Strip, Sheet, Wire · Annealed (Soft) · TYPICALUnit: MPa | ≥ 185 MPa | — MPa |
| Ultimate Tensile Strength · Strip, Sheet, Wire, Bar · Annealed (Soft) · TYPICALUnit: MPa | — MPa | ≥ 125 MPa |
| Elongation at Break · Strip, Sheet, Wire · Annealed (Soft) · TYPICALUnit: % | ≥ 35 % | — % |
| Elongation at Break · Strip, Sheet, Wire, Bar · in 50 mm (2 in) · Annealed (Soft) · TYPICALUnit: % | — % | ≥ 40 % |
| Poisson's Ratio · TYPICALUnit: dimensionless | — dimensionless | 0.37 dimensionless |
| Property | Britannia Silver 958 | Fine Silver 999 |
|---|---|---|
| Electrical Conductivity · TYPICAL · 20 °CCategory: ELECTRICAL • Unit: % IACS | 92 % IACS | 106 % IACS |
| Electrical Resistivity · TYPICAL · 20 °CCategory: ELECTRICAL • Unit: nΩ·m | — nΩ·m | 15.9 nΩ·m |
| Thermal Conductivity · TYPICAL · 20 °CCategory: THERMAL • Unit: W/(m·K) | 420 W/(m·K) | 429 W/(m·K) |
| Melting Range (Solidus-Liquidus) · RANGECategory: THERMAL • Unit: °C | 870–940 °C | — °C |
| Melting Point · TYPICALCategory: THERMAL • Unit: °C | — °C | 962 °C |
| Specific Heat Capacity · TYPICAL · 20 °CCategory: THERMAL • Unit: J/(kg·K) | — J/(kg·K) | 235 J/(kg·K) |
| Hardness Scale | Britannia Silver 958 | Fine Silver 999 |
|---|---|---|
| HV Hardness · Annealed (Soft) · TYPICAL | 48–62 HV | 25–35 HV |
Machinability: Rated at approximately 35% relative to C36000. Softer and more ductile than sterling silver; tends to form continuous chips requiring chip-breaker tool geometries.
Weldability: Readily brazed using silver-bearing filler metals. Less prone to deep firescale oxidation than sterling silver due to lower copper fraction.
Formability / Cold Working: Superb spinning and deep drawing performance; requires fewer intermediate annealing steps than 925 sterling.
Heat Treatment & Annealing: Annealed at 450°C to 550°C for 20 minutes, followed by water quench. Demonstrates minor precipitation hardening capability due to copper supersaturation.
Machinability: Rated at approximately 30% relative to free-cutting brass (C36000). Highly ductile and gummy; produces long continuous chips. Requires sharp high-rake carbide or diamond tooling, light feed rates, and continuous flood coolant to prevent tearing and galling.
Weldability: Weldable with gas tungsten arc (GTAW/TIG) and resistance welding; requires significant preheat and higher heat input due to extremely high thermal diffusivity (1.74 cm²/s). Readily brazed with silver-bearing fluxed fillers.
Formability / Cold Working: Exceptional cold workability. Capable of severe deep drawing, spinning, wire drawing down to micro-diameters, and cold swaging without intermediate annealing.
Heat Treatment & Annealing: Full recrystallization annealing occurs between 200°C and 300°C (392°F to 572°F) for 30 minutes, followed by rapid water quench or air cooling to preserve soft annealed ductility.