Precious Metal B780-ANN (Annealed)
Heat-treated state · default condition
GB B780
Pick for deep drawing, cold heading of contact rivets and any severe forming before final assembly.
Values for the ANN condition
Other B780 tempers and conditions
B780 is listed in 6 conditions; see the grade overview at B780.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefaultThis page Annealed | Pick for deep drawing, cold heading of contact rivets and any severe forming before final assembly. | 125 | 310 | 30 | 38 HRB | 78 % IACS |
1/8-Hard | Use when annealed strip is too soft to handle/blank cleanly but full forming ductility is still required. | 240 | 360 | 18 | 55 HRB | 77 % IACS |
Quarter hard | Balanced blanking/bending temper for stamped contact carriers and light spring blades. | 300 | 400 | 12 | 63 HRB | 76 % IACS |
Half hard | Most common temper for stamped moving contacts needing moderate stiffness with some bendability. | 400 | 470 | 6 | 74 HRB | 75 % IACS |
Full hard | Choose for maximum wear resistance and stiffness on flat contacts, sliding rings and shear-cut parts with minimal forming. | 500 | 550 | 3 | 84 HRB | 74 % IACS |
Spring | Highest strength and elastic limit — for self-sprung contact fingers, blades and clips where forming is limited to gentle radii. | 690 | 760 | 2 | 98 HRB | 56 % IACS |
What is B780-ANN?
B780-ANN is B780 heat treated to ANN — pick for deep drawing, cold heading of contact rivets and any severe forming before final assembly. B780-ANN has a yield strength of 125 MPa (18.1 ksi) and a tensile strength of 310 MPa (45 ksi) — weaker than 74% of precious metal grades. Elongation at break is 30% and the elastic modulus is 88 GPa (12.8 Msi). B780-ANN has a density of 10.05 g/cm³ (0.363 lb/in³), lighter than 64% of precious metal grades. It melts at 779°C (1,434 °F).
Advantages
- Conducts heat well — 320 W/m·K (184.9 BTU/hr·ft·°F), better than 80% of precious metal grades
- High electrical conductivity — 78 % IACS, better than 79% of precious metal grades
B780-ANN properties
Typical room-temperature values for B780-ANN; 16 are specific to this condition. Other listed values are B780 reference data and may not represent this condition. Bars are the position among precious metal grades.
Physical3
B780-ANN has a density of 10.05 g/cm³ (0.363 lb/in³), lighter than 64% of precious metal grades. It melts at 779°C (1,434 °F).
Mechanical13
B780-ANN has a yield strength of 125 MPa (18.1 ksi) and a tensile strength of 310 MPa (45 ksi) — weaker than 74% of precious metal grades. Elongation at break is 30% and the elastic modulus is 88 GPa (12.8 Msi).
Thermal6
B780-ANN is rated for continuous service to 250°C (482 °F). It conducts heat at 320 W/m·K (184.9 BTU/hr·ft·°F), better than 80% of precious metal grades. Thermal expansion is 18.5 µm/m·K (10.3 µin/in·°F).
Electrical3
B780-ANN conducts electricity at 78 % IACS, better than 79% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is very good (75/100), worse than 61% of precious metal grades.
Sustainability4
Producing a kilogram of B780-ANN takes about 1,200 MJ of energy and emits 95 kg of CO₂ — less than 66% of precious metal grades. Typical recycled content is 45%.
Manufacturability8
B780-ANN's machinability is fair (50/100, better than 74% of precious metal grades); weldability good (60/100); formability excellent (85/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with B780-ANN
Is B780 easy to machine?
Machines like soft copper — very gummy; use sharp, high-rake carbide or HSS tools, high speed, light feed and flood lubricant, and collect all chips for refining.
Can B780 be welded?
Joined almost exclusively by resistance/projection welding, laser welding or brazing of contact buttons to carriers; fusion arc welding is not practiced.
Can B780 be formed, bent or molded?
Excellent cold formability in the annealed temper (deep drawing, cold heading, wire-to-rivet upsetting); interanneal near 600–650 °C in a low-sulfur atmosphere between heavy reductions.
What surface finishes work on B780?
Bright-dip or electropolish; apply anti-tarnish passivation or a thin gold/rhodium flash for low-level signal contacts, and avoid sulfur-containing packaging elastomers.
B780 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 |
|---|---|---|
| Agsilver content per ASTM B780 | 74.5 – 75.5 | 75 |
| Nigrain refiner / hardener | 0.4 – 0.6 | 0.5 |
| Other (total impurities)typical total residual limit | ≤ 0.15 | — |
| Cubalance copper | balance | — |
B780-ANN — frequently asked
What is B780-ANN used for?
B780-ANN is typically used for switchgear contacts, relay contact tips and connector wear surfaces. In short: harder than coin silver; high-conductivity silver contact; tarnishes in sulfur air.
What is the yield strength of B780-ANN?
B780-ANN has a typical yield strength of 125 MPa (18.1 ksi) and a tensile strength of 310 MPa (45 ksi) — weaker than 74% of precious metal grades. Strength varies by condition: see the 6 listed tempers.
Is B780-ANN easy to machine?
Reasonably — machinability is rated fair (50/100, better than 74% of precious metal grades). Machines like soft copper — very gummy; use sharp, high-rake carbide or HSS tools, high speed, light feed and flood lubricant, and collect all chips for refining.
Can B780-ANN be welded?
Yes — weldability is rated good (60/100). Joined almost exclusively by resistance/projection welding, laser welding or brazing of contact buttons to carriers; fusion arc welding is not practiced.
What surface finishes work on B780-ANN?
Bright-dip or electropolish; apply anti-tarnish passivation or a thin gold/rhodium flash for low-level signal contacts, and avoid sulfur-containing packaging elastomers.
Can B780-ANN be formed, bent or molded?
Excellent cold formability in the annealed temper (deep drawing, cold heading, wire-to-rivet upsetting); interanneal near 600–650 °C in a low-sulfur atmosphere between heavy reductions.
What is the maximum service temperature of B780-ANN?
B780-ANN is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between B780-ANN and B780-SPR?
ANN is the default condition — pick for deep drawing, cold heading of contact rivets and any severe forming before final assembly. SPR: highest strength and elastic limit — for self-sprung contact fingers, blades and clips where forming is limited to gentle radii. Yield strength is 125 MPa in ANN versus 690 MPa in SPR.
Sources
- ASTM B780 Standard Specification for 75 % Silver, 24.5 % Copper, 0.5 % Nickel Electrical Contact Alloy — ASTM International (2020)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (precious metals & electrical contact materials) — ASM International (1990)
- ASM Handbook Vol. 3 — Alloy Phase Diagrams (Ag-Cu system) — ASM International (1992)
- Electrical contact material datasheets (Ag-Cu and Ag-Cu-Ni strip/rivet stock) — Precious-metal contact fabricators (2023)
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.