Precious Metal B685 1/4H
Supply condition
GB B685
1/4H = quarter hard
Compromise temper for stamped contact springs that still need moderate bending without cracking.
Values for the 1/4H condition
Other B685 tempers and conditions
B685 is listed in 4 conditions; see the grade overview at B685.
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 |
1/4HThis page 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 1/4H?
B685 1/4H is B685 supplied in the 1/4H condition — compromise temper for stamped contact springs that still need moderate bending without cracking. B685 1/4H has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 97% of precious metal grades. Elongation at break is 15% and the elastic modulus is 130 GPa (18.9 Msi). B685 1/4H 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). O is the default condition FabDigit quotes; 1/4H is available on request or by drawing note.
Advantages
- High strength — 450 MPa (65.3 ksi), better than 97% of precious metal grades
- 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 — 4.9 % IACS, worse than 98% of precious metal grades
- Limited ductility — 15%, worse than 86% of precious metal grades
- Difficult to machine — 30/100, worse than 86% of precious metal grades
- Limited formability — 65/100, worse than 86% of precious metal grades
B685 1/4H properties
Typical room-temperature values for B685 1/4H; 10 are specific to this condition. Other listed values are B685 reference data and may not represent this condition. Bars are the position among precious metal grades.
Physical3
B685 1/4H 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 1/4H has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 97% of precious metal grades. Elongation at break is 15% and the elastic modulus is 130 GPa (18.9 Msi).
Thermal6
B685 1/4H is rated for continuous service to 300°C (572 °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 1/4H conducts electricity at 4.9 % IACS, worse than 98% 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 1/4H 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 1/4H's machinability is poor (30/100, worse than 86% of precious metal grades); weldability good (62/100); formability good (65/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with B685 1/4H
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.
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.
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) | — |
B685 1/4H — frequently asked
What is B685 1/4H used for?
B685 1/4H 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 1/4H?
B685 1/4H has a typical yield strength of 450 MPa (65.3 ksi) and a tensile strength of 620 MPa (89.9 ksi) — stronger than 97% of precious metal grades. Strength varies by condition: see the 4 listed tempers.
Is B685 1/4H 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 1/4H 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 1/4H?
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 1/4H 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 1/4H?
B685 1/4H is rated for continuous use to about 300°C (572 °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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.