Precious Metal B477
GB B477
ASTM B477 covers a gold-based electrical contact alloy hardened with nickel and alloyed with silver, supplied in Tempers A through D.
Reference datasheet — B477 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 A condition
B477 tempers and conditions
B477 is supplied in 4 conditions, soft to hard. A is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Softest mill condition for deep drawing, coining, cladding and riveting of contact blanks before any age hardening. | 250 | 470 | 30 | 130 HV | 9 % IACS |
Temper B | Intermediate temper when the part still needs bending or staking but higher contact-face hardness than annealed. | 500 | 650 | 14 | 190 HV | 9.3 % IACS |
Temper C | Hard strip/wire for contact springs and low-wear sliding contacts where only mild forming is required. | 700 | 800 | 6 | 240 HV | 9.5 % IACS |
Temper D | Maximum hardness condition (cold work plus nickel age-hardening heat treatment) for self-sprung contact fingers and wear-critical low-level switching. | 890 | 980 | 3 | 300 HV | 11 % IACS |
What is B477?
ASTM B477 covers a gold-based electrical contact alloy hardened with nickel and alloyed with silver, supplied in Tempers A through D. Engineers specify it for low, stable contact resistance and a tarnish-free surface in low-level signal switching, usually as strip, fine wire, coined rivets and clad contact strip rather than solid parts. Electrical conductivity is only 9% IACS, thermal conductivity 40 W/m·K and service is limited to about 400 °C, and the precious-metal content dominates cost. Where a harder wiping surface is needed, the Au-Ag-Pt alloys of ASTM B522 are the nearest alternative. B477 has a density of 15 g/cm³ (0.542 lb/in³), heavier than 75% of precious metal grades. It melts at 960°C (1,760 °F). B477 has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 470 MPa (68.2 ksi) — stronger than 81% of precious metal grades. Elongation at break is 30% and the elastic modulus is 100 GPa (14.5 Msi).
What is B477 used for?
- low-level signal contacts
- connector contacts
- precision relays
Advantages
- Polishes to a fine finish — 95/100, better than 86% of precious metal grades
- Good corrosion resistance — 95/100, better than 82% of precious metal grades
- High strength — 250 MPa (36.3 ksi), better than 81% of precious metal grades
Limitations
- Poor heat conductor — 40 W/m·K (23.1 BTU/hr·ft·°F), worse than 85% of precious metal grades
- Low electrical conductivity — 9 % IACS, worse than 84% of precious metal grades
- Heavy — 15 g/cm³ (0.542 lb/in³), worse than 75% of precious metal grades
B477 properties
Typical room-temperature values for B477-A; bars are the position among precious metal grades.
Physical3
B477 has a density of 15 g/cm³ (0.542 lb/in³), heavier than 75% of precious metal grades. It melts at 960°C (1,760 °F).
Mechanical10
B477 has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 470 MPa (68.2 ksi) — stronger than 81% of precious metal grades. Elongation at break is 30% and the elastic modulus is 100 GPa (14.5 Msi).
Thermal6
B477 is rated for continuous service to 400°C (752 °F). It conducts heat at 40 W/m·K (23.1 BTU/hr·ft·°F), worse than 85% of precious metal grades. Thermal expansion is 15 µm/m·K (8.33 µin/in·°F).
Electrical3
B477 conducts electricity at 9 % IACS, worse than 84% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (95/100), better than 82% of precious metal grades.
Sustainability4
Producing a kilogram of B477 takes about 150,000 MJ of energy and emits 11,000 kg of CO₂ — more than 73% of precious metal grades. Typical recycled content is 60%.
Manufacturability8
B477's machinability is fair (40/100, worse than 60% of precious metal grades); weldability good (65/100); formability excellent (90/100).
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. B477 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with B477
Is B477 easy to machine?
Machine with sharp, high-rake carbide or diamond tooling, light cuts and oil mist; soft tempers are gummy and chips must be recovered for refining.
Can B477 be welded?
Joined to substrates by resistance, percussion or laser welding and by brazing; conventional arc welding is not used.
Can B477 be formed, bent or molded?
Temper A strip stamps, coins, draws and rivets easily; harden by cold work plus a low-temperature nickel ageing treatment after forming for Temper D properties.
B477 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 |
|---|---|---|
| Augold, principal element | 68.5 – 69.5 | 69 |
| Ag | 24.5 – 25.5 | 25 |
| Nihardening addition | 5.5 – 6.5 | 6 |
| Other (total impurities)per ASTM B477 impurity limit | ≤ 0.15 | — |
What surface finishes work on B477?
Used bare with a bright buffed or burnished contact face; optional hard-gold or Rh flash plating; no anodizing, and avoid sulfur-bearing polishing compounds.
How much does B477 cost?
B477 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.
B477 — frequently asked
What is B477 used for?
B477 is typically used for low-level signal contacts, connector contacts and precision relays. In short: nickel-hardened gold contact alloy; tarnish-free signal surface; formable in Temper A.
What is the yield strength of B477?
B477 has a typical yield strength of 250 MPa (36.3 ksi) and a tensile strength of 470 MPa (68.2 ksi) — stronger than 81% of precious metal grades. Strength varies by condition: see the 4 listed tempers.
Is B477 easy to machine?
Not especially — machinability is rated fair (40/100, worse than 60% of precious metal grades). Machine with sharp, high-rake carbide or diamond tooling, light cuts and oil mist; soft tempers are gummy and chips must be recovered for refining.
Can B477 be welded?
Yes — weldability is rated good (65/100). Joined to substrates by resistance, percussion or laser welding and by brazing; conventional arc welding is not used.
What surface finishes work on B477?
Used bare with a bright buffed or burnished contact face; optional hard-gold or Rh flash plating; no anodizing, and avoid sulfur-bearing polishing compounds.
Can B477 be formed, bent or molded?
Temper A strip stamps, coins, draws and rivets easily; harden by cold work plus a low-temperature nickel ageing treatment after forming for Temper D properties.
What is the maximum service temperature of B477?
B477 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between B477-A and B477-D?
A is the default condition — softest mill condition for deep drawing, coining, cladding and riveting of contact blanks before any age hardening. D: maximum hardness condition (cold work plus nickel age-hardening heat treatment) for self-sprung contact fingers and wear-critical low-level switching. Yield strength is 250 MPa in A versus 890 MPa in D.
How much does B477 cost?
B477 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 B477 Standard Specification for Gold-Silver-Nickel Electrical Contact Material — ASTM International (2019)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Precious Metals, Electrical Contact Materials) — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials (Precious Metals) — ASM International (2005)
- Precious-metal electrical contact alloy strip and wire datasheets (Au-Ag-Ni family) — Deringer-Ney / Heraeus (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.