Precious Metal B596-OA (Order-hardened)
Heat-treated state
GB B596
Choose for maximum hardness, wear life and the lowest resistivity, after parts are formed.
Values for the OA condition
Other B596 tempers and conditions
B596 is listed in 4 conditions; see the grade overview at B596.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Pick for forming, heading, riveting or coiling of contacts before final hardening. | 190 | 420 | 32 | 135 HV | 16 % IACS |
Half hard | Intermediate temper when both moderate spring force and some bending ductility are needed. | 450 | 600 | 10 | 166 HB | 15 % IACS |
HDefault Hardened | Default stock condition for sliding, wiping and slip-ring contacts needing wear resistance and contact force. | 620 | 760 | 3 | 215 HV | 15 % IACS |
OAThis page Order-hardened | Choose for maximum hardness, wear life and the lowest resistivity, after parts are formed. | 780 | 900 | 3 | 265 HV | 25 % IACS |
What is B596-OA?
B596-OA is B596 heat treated to OA — choose for maximum hardness, wear life and the lowest resistivity, after parts are formed. B596-OA has a yield strength of 780 MPa (113 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 100% of precious metal grades. Elongation at break is 3% and the elastic modulus is 92 GPa (13.3 Msi). B596-OA has a density of 15.5 g/cm³ (0.56 lb/in³), heavier than 77% of precious metal grades. It melts at 885°C (1,625 °F). H is the default condition FabDigit quotes; OA is available on request or by drawing note.
Advantages
- High strength — 780 MPa (113 ksi), better than 100% of precious metal grades
- Easy to machine — 55/100, better than 86% of precious metal grades
- Polishes to a fine finish — 95/100, better than 86% of precious metal grades
- Readily welded — 75/100, better than 78% of precious metal grades
Limitations
- Limited formability — 20/100, worse than 96% of precious metal grades
- Limited ductility — 3%, worse than 95% of precious metal grades
- Heavy — 15.5 g/cm³ (0.56 lb/in³), worse than 77% of precious metal grades
- High embodied carbon — 12,000 kg CO₂/kg, worse than 76% of precious metal grades
B596-OA properties
Typical room-temperature values for B596-OA; 10 are specific to this condition. Other listed values are B596 reference data and may not represent this condition. Bars are the position among precious metal grades.
Physical3
B596-OA has a density of 15.5 g/cm³ (0.56 lb/in³), heavier than 77% of precious metal grades. It melts at 885°C (1,625 °F).
Mechanical10
B596-OA has a yield strength of 780 MPa (113 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 100% of precious metal grades. Elongation at break is 3% and the elastic modulus is 92 GPa (13.3 Msi).
Thermal6
B596-OA is rated for continuous service to 250°C (482 °F). It conducts heat at 100 W/m·K (57.8 BTU/hr·ft·°F), better than 55% of precious metal grades. Thermal expansion is 16 µm/m·K (8.89 µin/in·°F).
Electrical3
B596-OA conducts electricity at 25 % IACS, better than 64% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (90/100), better than 69% of precious metal grades.
Sustainability4
Producing a kilogram of B596-OA takes about 200,000 MJ of energy and emits 12,000 kg of CO₂ — more than 85% of precious metal grades. Typical recycled content is 45%.
Manufacturability8
B596-OA's machinability is good (55/100, better than 86% of precious metal grades); weldability very good (75/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with B596-OA
Is B596 easy to machine?
Turns and skives cleanly with sharp, polished-rake carbide or diamond tooling and light oil; keep all swarf for refining.
Can B596 be welded?
Resistance, percussion and laser welding to contact carriers are standard; avoid gas welding to prevent copper oxidation and gold loss.
Can B596 be formed, bent or molded?
Anneal at 600–700 °C in reducing or inert atmosphere and quench to the soft, disordered state before heavy drawing, coiling or heading; cold-work rates of 40–60 % between anneals are routine.
What surface finishes work on B596?
Bright-drawn or buffed to a mirror finish; no plating needed, but hard-gold flash or Rh overlay is occasionally applied to wiping surfaces.
B596 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 content per specification (18 karat class) | 74.5 – 75.5 | 75 |
| Agincidental | ≤ 0.1 | — |
| Other (total impurities)total of all elements other than Au and Cu | ≤ 0.15 | — |
| Cubalance copper | balance | — |
B596-OA — frequently asked
What is B596-OA used for?
B596-OA is typically used for slip rings, potentiometers and connector contacts. In short: hardest gold contact alloy; tarnish-free wiping contacts; low conductivity, gold cost.
What is the yield strength of B596-OA?
B596-OA has a typical yield strength of 780 MPa (113 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 100% of precious metal grades. Strength varies by condition: see the 4 listed tempers.
Is B596-OA easy to machine?
Reasonably — machinability is rated good (55/100, better than 86% of precious metal grades). Turns and skives cleanly with sharp, polished-rake carbide or diamond tooling and light oil; keep all swarf for refining.
Can B596-OA be welded?
Yes — weldability is rated very good (75/100). Resistance, percussion and laser welding to contact carriers are standard; avoid gas welding to prevent copper oxidation and gold loss.
What surface finishes work on B596-OA?
Bright-drawn or buffed to a mirror finish; no plating needed, but hard-gold flash or Rh overlay is occasionally applied to wiping surfaces.
Can B596-OA be formed, bent or molded?
Anneal at 600–700 °C in reducing or inert atmosphere and quench to the soft, disordered state before heavy drawing, coiling or heading; cold-work rates of 40–60 % between anneals are routine.
What is the maximum service temperature of B596-OA?
B596-OA 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 B596-H and B596-O?
H is the default condition — default stock condition for sliding, wiping and slip-ring contacts needing wear resistance and contact force. O: pick for forming, heading, riveting or coiling of contacts before final hardening. Yield strength is 620 MPa in H versus 190 MPa in O.
Sources
- ASTM B596 — Specification for Gold-Copper Alloy Electrical Contact Material — ASTM International (2021)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (precious metals and electrical contact materials) — ASM International (1990)
- ASM Alloy Phase Diagrams — Au-Cu system — ASM International (2016)
- Precious-metal contact wire and strip alloy data (Au-Cu tempers) — Deringer-Ney / Heraeus (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.