Precious Metal B596-O (Annealed)
Temper
GB B596
Pick for forming, heading, riveting or coiling of contacts before final hardening.
Values for the O 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 |
|---|---|---|---|---|---|---|
OThis page 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 |
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-O?
B596-O is B596 in the O temper — pick for forming, heading, riveting or coiling of contacts before final hardening. B596-O has a yield strength of 190 MPa (27.6 ksi) and a tensile strength of 420 MPa (60.9 ksi) — weaker than 56% of precious metal grades. Elongation at break is 32% and the elastic modulus is 92 GPa (13.3 Msi). B596-O 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; O is available on request or by drawing note.
Advantages
- Readily welded — 80/100, better than 87% of precious metal grades
- Polishes to a fine finish — 95/100, better than 86% of precious metal grades
- Ductile — tolerates forming and impact — 32%, better than 75% of precious metal grades
Limitations
- 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-O properties
Typical room-temperature values for B596-O; 14 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-O 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-O has a yield strength of 190 MPa (27.6 ksi) and a tensile strength of 420 MPa (60.9 ksi) — weaker than 56% of precious metal grades. Elongation at break is 32% and the elastic modulus is 92 GPa (13.3 Msi).
Thermal6
B596-O is rated for continuous service to 300°C (572 °F). It conducts heat at 66 W/m·K (38.1 BTU/hr·ft·°F), worse than 65% of precious metal grades. Thermal expansion is 16 µm/m·K (8.89 µin/in·°F).
Electrical3
B596-O conducts electricity at 16 % IACS, worse than 60% 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-O 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-O's machinability is fair (45/100, better than 59% of precious metal grades); weldability very good (80/100); formability excellent (88/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with B596-O
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-O — frequently asked
What is B596-O used for?
B596-O 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-O?
B596-O has a typical yield strength of 190 MPa (27.6 ksi) and a tensile strength of 420 MPa (60.9 ksi) — weaker than 56% of precious metal grades. Strength varies by condition: see the 4 listed tempers.
Is B596-O easy to machine?
Reasonably — machinability is rated fair (45/100, better than 59% 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-O be welded?
Yes — weldability is rated very good (80/100). 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-O?
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-O 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-O?
B596-O 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 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.