Precious Metal B685
GB B685
ASTM B685 covers wrought palladium-copper contact alloy, supplied in annealed through hard tempers (O, 1/4H, 1/2H, H).
Reference datasheet — B685 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 O condition
B685 tempers and conditions
B685 is supplied in 4 conditions, soft to hard. O 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 |
|---|---|---|---|---|---|---|
ODefault Annealed | Choose for maximum ductility when the part must be deep-drawn, headed, coined into rivets or wire-bonded before final forming. | 200 | 500 | 30 | 78 HRB | 5 % IACS |
Quarter hard | Compromise temper for stamped contact springs that still need moderate bending without cracking. | 450 | 620 | 15 | 90 HRB | 4.9 % IACS |
Half hard | Standard temper for reed and leaf contact blades needing spring force with limited forming. | 620 | 760 | 8 | 19 HRC | 4.8 % IACS |
Hardened | Choose for maximum hardness, wear resistance and contact spring force in low-energy relay and connector contacts; very little forming possible after supply. | 860 | 1,000 | 2.5 | 26 HRC | 4.7 % IACS |
What is B685?
ASTM B685 covers wrought palladium-copper contact alloy, supplied in annealed through hard tempers (O, 1/4H, 1/2H, H). Engineers use it for low-energy signal switching where tarnish resistance, low contact resistance and minimal sparking or material transfer are required; typical forms are strip, wire, contact rivets and stamped blades, with 500 MPa tensile strength, 30% elongation and 78 HRB. Conductivity is only 5% IACS and thermal conductivity 22 W/m·K, so it is unsuited to power switching, and palladium cost pushes designs toward thin claddings. ASTM B780 Ag-Cu-Ni is the higher-conductivity alternative. B685 has a density of 10.4 g/cm³ (0.376 lb/in³), heavier than 51% of precious metal grades. It melts at 1,200°C (2,192 °F). B685 has a yield strength of 200 MPa (29 ksi) and a tensile strength of 500 MPa (72.5 ksi) — stronger than 51% of precious metal grades. Elongation at break is 30% and the elastic modulus is 130 GPa (18.9 Msi).
What is B685 used for?
- telecom relay contacts
- low-level signal switch contacts
- precision instrument contacts
Advantages
- Stiff — 130 GPa (18.9 Msi), better than 83% of precious metal grades
Limitations
- Poor heat conductor — 22 W/m·K (12.7 BTU/hr·ft·°F), worse than 98% of precious metal grades
- Low electrical conductivity — 5 % IACS, worse than 97% of precious metal grades
- Difficult to machine — 30/100, worse than 86% of precious metal grades
B685 properties
Typical room-temperature values for B685-O; bars are the position among precious metal grades.
Physical3
B685 has a density of 10.4 g/cm³ (0.376 lb/in³), heavier than 51% of precious metal grades. It melts at 1,200°C (2,192 °F).
Mechanical12
B685 has a yield strength of 200 MPa (29 ksi) and a tensile strength of 500 MPa (72.5 ksi) — stronger than 51% of precious metal grades. Elongation at break is 30% and the elastic modulus is 130 GPa (18.9 Msi).
Thermal6
B685 is rated for continuous service to 450°C (842 °F). It conducts heat at 22 W/m·K (12.7 BTU/hr·ft·°F), worse than 98% of precious metal grades. Thermal expansion is 14 µm/m·K (7.78 µin/in·°F).
Electrical3
B685 conducts electricity at 5 % IACS, worse than 97% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (92/100), better than 73% of precious metal grades.
Sustainability4
Producing a kilogram of B685 takes about 24,000 MJ of energy and emits 2,200 kg of CO₂ — more than 59% of precious metal grades. Typical recycled content is 45%.
Manufacturability8
B685's machinability is poor (30/100, worse than 86% of precious metal grades); weldability good (62/100); formability excellent (88/100).
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. B685 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with B685
Is B685 easy to machine?
Gummy and abrasive-free but expensive — use sharp carbide/HSS tools, positive rake, light feeds and full swarf recovery for refining.
Can B685 be welded?
Resistance, laser and micro-TIG welding of contact rivets and blades works well; avoid sulfur-bearing fluxes and keep heat input low to retain cold-worked hardness.
Can B685 be formed, bent or molded?
Excellent cold drawability and stampability in the annealed temper (interanneal ~750–850 °C in inert or reducing atmosphere); hard temper tolerates only gentle radii.
B685 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 |
|---|---|---|
| Pdpalladium content per ASTM B685 | 59 – 61 | 60 |
| Other (total)total impurities/other elements | ≤ 0.15 | — |
| Cubalance copper | ≥ 39 (balance) | — |
What surface finishes work on B685?
Not anodizable; polishes to a bright tarnish-stable surface and can carry a thin gold or Pd flash for storage protection and lowest dry-circuit contact resistance.
Equivalent designations
Standards and trade names that resolve to Precious Metal B685 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Also called
- 60Pd-40Cu
How much does B685 cost?
B685 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.
B685 — frequently asked
What is B685 used for?
B685 is typically used for telecom relay contacts, low-level signal switch contacts and precision instrument contacts. In short: tarnish-resistant signal contact; low sparking and transfer; poor conductor, dry-circuit use.
What is the yield strength of B685?
B685 has a typical yield strength of 200 MPa (29 ksi) and a tensile strength of 500 MPa (72.5 ksi) — stronger than 51% of precious metal grades. Strength varies by condition: see the 4 listed tempers.
Is B685 easy to machine?
Not especially — machinability is rated poor (30/100, worse than 86% of precious metal grades). Gummy and abrasive-free but expensive — use sharp carbide/HSS tools, positive rake, light feeds and full swarf recovery for refining.
Can B685 be welded?
Yes — weldability is rated good (62/100). Resistance, laser and micro-TIG welding of contact rivets and blades works well; avoid sulfur-bearing fluxes and keep heat input low to retain cold-worked hardness.
What surface finishes work on B685?
Not anodizable; polishes to a bright tarnish-stable surface and can carry a thin gold or Pd flash for storage protection and lowest dry-circuit contact resistance.
Can B685 be formed, bent or molded?
Excellent cold drawability and stampability in the annealed temper (interanneal ~750–850 °C in inert or reducing atmosphere); hard temper tolerates only gentle radii.
What is the maximum service temperature of B685?
B685 is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between B685-O and B685-H?
O is the default condition — choose for maximum ductility when the part must be deep-drawn, headed, coined into rivets or wire-bonded before final forming. H: choose for maximum hardness, wear resistance and contact spring force in low-energy relay and connector contacts; very little forming possible after supply. Yield strength is 200 MPa in O versus 860 MPa in H.
How much does B685 cost?
B685 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 B685 — Standard Specification for Wrought Palladium-Copper Alloy for Electrical Contacts — ASTM International (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (precious metals and electrical contact materials) — ASM International (1990)
- ASM Handbook Vol. 3 — Alloy Phase Diagrams (Cu-Pd system) — ASM International (1992)
- Palladium-copper contact wire and strip data (precious-metal contact fabricators) — Various producers (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.