Precious Metal B780
GB B780
ASTM B780 is a silver-copper alloy with a nickel addition for grain refinement, giving higher hardness and wear resistance than plain coin silver while retaining 78% IACS and 320 W/m·K.
Reference datasheet — B780 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the ANN condition
B780 tempers and conditions
B780 is supplied in 6 conditions, soft to hard. ANN is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefault 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?
ASTM B780 is a silver-copper alloy with a nickel addition for grain refinement, giving higher hardness and wear resistance than plain coin silver while retaining 78% IACS and 320 W/m·K. It is specified for moderate-duty contacts and wear surfaces and is available in annealed through spring tempers (ANN, 1/8H, 1/4H, 1/2H, FH, SPR) as strip, wire and cold-headed rivets, with 310 MPa tensile strength, 30% elongation and 38 HRB. Service is limited to about 250 °C and the silver surface tarnishes in sulfur-bearing air; Ag-CdO or Ag-Ni composites are used where arcing duty is heavier. B780 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). B780 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).
What is B780 used for?
- switchgear contacts
- relay contact tips
- connector wear surfaces
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 properties
Typical room-temperature values for B780-ANN; bars are the position among precious metal grades.
Physical3
B780 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 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 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 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 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'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. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the precious metal family
Yield strength against density for every precious metal grade FabDigit runs. B780 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with B780
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.
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 | — |
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.
Equivalent designations
Standards and trade names that resolve to Precious Metal B780 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Also called
- Ag-Cu-Ni Contact Alloy
How much does B780 cost?
B780 is a high-cost precious metal ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
B780 — frequently asked
What is B780 used for?
B780 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?
B780 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 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 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?
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 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?
B780 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.
How much does B780 cost?
B780 is a high-cost precious metal ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.