Precious Metal B540-DH (Ductile hardened)
Supply condition
GB B540
Choose for sliding contacts, brushes and formed springs needing higher hardness and wear life while still permitting bending and riveting.
Values for the DH condition
Other B540 tempers and conditions
B540 is listed in 4 conditions; see the grade overview at B540.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SADefault Solution annealed | Standard stocked soft temper for stamping, drawing and cladding of contact strip and wire; maximum ductility and lowest contact resistance. | 55 | 195 | 35 | 44 HB | 16 % IACS |
Stress relieved | Pick when formed contact springs and rivets need dimensional stability and reduced springback distortion without losing all cold-work strength. | 170 | 260 | 22 | 68 HB | 15.5 % IACS |
DHThis page Ductile hardened | Choose for sliding contacts, brushes and formed springs needing higher hardness and wear life while still permitting bending and riveting. | 280 | 330 | 10 | 100 HB | 14.8 % IACS |
Age (order) hardened Pd-Cu / Pd-Ag-Cu alloy grade | Use for high-wear, low-force sliding contacts, slip rings and probe tips where maximum hardness and erosion resistance are needed; applies to the ordering Pd-Cu/Pd-Ag-Cu alloy grades, not to pure palladium. | 550 | 750 | 8 | 22 HRC | 6 % IACS |
What is B540-DH?
B540-DH is B540 supplied in the DH condition — choose for sliding contacts, brushes and formed springs needing higher hardness and wear life while still permitting bending and riveting. B540-DH has a yield strength of 280 MPa (40.6 ksi) and a tensile strength of 330 MPa (47.9 ksi) — stronger than 88% of precious metal grades. Elongation at break is 10% and the elastic modulus is 121 GPa (17.5 Msi). B540-DH has a density of 12.02 g/cm³ (0.434 lb/in³), heavier than 67% of precious metal grades. It melts at 1,554°C (2,829 °F). SA is the default condition FabDigit quotes; DH is available on request or by drawing note.
Advantages
- High strength — 280 MPa (40.6 ksi), better than 88% of precious metal grades
- Good corrosion resistance — 95/100, better than 82% of precious metal grades
- Stiff — 121 GPa (17.5 Msi), better than 80% of precious metal grades
Limitations
- Limited ductility — 10%, worse than 89% of precious metal grades
- Limited formability — 55/100, worse than 89% of precious metal grades
B540-DH properties
Typical room-temperature values for B540-DH; 16 are specific to this condition. Other listed values are B540 reference data and may not represent this condition. Bars are the position among precious metal grades.
Physical3
B540-DH has a density of 12.02 g/cm³ (0.434 lb/in³), heavier than 67% of precious metal grades. It melts at 1,554°C (2,829 °F).
Mechanical12
B540-DH has a yield strength of 280 MPa (40.6 ksi) and a tensile strength of 330 MPa (47.9 ksi) — stronger than 88% of precious metal grades. Elongation at break is 10% and the elastic modulus is 121 GPa (17.5 Msi).
Thermal6
B540-DH is rated for continuous service to 250°C (482 °F). It conducts heat at 69 W/m·K (39.9 BTU/hr·ft·°F), worse than 65% of precious metal grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
B540-DH conducts electricity at 14.8 % IACS, worse than 68% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (95/100), better than 82% of precious metal grades.
Sustainability4
Producing a kilogram of B540-DH takes about 55,000 MJ of energy and emits 3,900 kg of CO₂ — more than 62% of precious metal grades. Typical recycled content is 60%.
Manufacturability8
B540-DH's machinability is fair (45/100, better than 59% of precious metal grades); weldability good (65/100); formability good (55/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with B540-DH
Is B540 easy to machine?
Soft and gummy — use sharp positive-rake carbide/diamond tools, high speed, light feed and copious lubrication; collect all chips for refining.
Can B540 be welded?
Resistance, laser and micro-TIG welding of contacts to Cu/CuNi carriers is routine; avoid hydrogen-rich flames to prevent H absorption and embrittlement.
Can B540 be formed, bent or molded?
Excellent cold formability in the annealed temper (stamping, deep drawing, cladding to Ag/Cu strip); interanneal at 700–900 °C in clean inert or slightly oxidizing atmosphere.
What surface finishes work on B540?
No anodizing; finish by polishing, electropolishing or thin Au/Rh flash plating to suppress organic 'brown powder' formation in dry-circuit switching.
B540 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.
| Element | Spec limit (wt %) |
|---|---|
| Ptimpurity limit, pure grade | ≤ 0.02 |
| Rhimpurity limit | ≤ 0.02 |
| Ir+Ruimpurity limit | ≤ 0.02 |
| Feimpurity limit | ≤ 0.01 |
| Cuimpurity limit, pure grade | ≤ 0.01 |
| Pbimpurity limit | ≤ 0 |
| Other elements, totalsum of impurities | ≤ 0.05 |
| PdPure palladium contact grade of ASTM B540; alloy grades of the same specification substitute Ag (up to ~40 %), Cu (up to ~40 %) or Ru (up to ~10 %) for part of the Pd | ≥ 99.95 (balance) |
B540-DH — frequently asked
What is B540-DH used for?
B540-DH is typically used for telecom relays, low-power switches and dry-circuit contacts. In short: tarnish-resistant palladium contact; softest, most formable grade here; dry-circuit relay standard.
What is the yield strength of B540-DH?
B540-DH has a typical yield strength of 280 MPa (40.6 ksi) and a tensile strength of 330 MPa (47.9 ksi) — stronger than 88% of precious metal grades. Strength varies by condition: see the 4 listed tempers.
Is B540-DH easy to machine?
Reasonably — machinability is rated fair (45/100, better than 59% of precious metal grades). Soft and gummy — use sharp positive-rake carbide/diamond tools, high speed, light feed and copious lubrication; collect all chips for refining.
Can B540-DH be welded?
Yes — weldability is rated good (65/100). Resistance, laser and micro-TIG welding of contacts to Cu/CuNi carriers is routine; avoid hydrogen-rich flames to prevent H absorption and embrittlement.
What surface finishes work on B540-DH?
No anodizing; finish by polishing, electropolishing or thin Au/Rh flash plating to suppress organic 'brown powder' formation in dry-circuit switching.
Can B540-DH be formed, bent or molded?
Excellent cold formability in the annealed temper (stamping, deep drawing, cladding to Ag/Cu strip); interanneal at 700–900 °C in clean inert or slightly oxidizing atmosphere.
What is the maximum service temperature of B540-DH?
B540-DH 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 B540-SA and B540-AH?
SA is the default condition — standard stocked soft temper for stamping, drawing and cladding of contact strip and wire; maximum ductility and lowest contact resistance. AH: use for high-wear, low-force sliding contacts, slip rings and probe tips where maximum hardness and erosion resistance are needed; applies to the ordering Pd-Cu/Pd-Ag-Cu alloy grades, not to pure palladium. Yield strength is 55 MPa in SA versus 550 MPa in AH.
Sources
- ASTM B540 — Standard Specification for Palladium Electrical Contact Material — ASTM International (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Precious Metals & Electrical Contact Materials) — ASM International (1990)
- Precious Metal Contact Materials — Palladium and Palladium Alloys — Johnson Matthey (2020)
- CRC Handbook of Chemistry and Physics — Physical Properties of the Elements (Pd) — CRC Press (2022)
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.