Precious Metal AuNi-H08
Supply condition
H08 = spring hard
Highest strength temper for fine contact springs and probe wires; almost no formability left.
Values for the H08 condition
Other AuNi tempers and conditions
AuNi is listed in 6 conditions; see the grade overview at AuNi.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As cast | Intermediate form from the refinery before rolling/drawing; not used in service. | 150 | 350 | 20 | 105 HB | 12.5 % IACS |
Annealed | Pick for deep drawing, riveting, bonding wire and any part that must be formed before service. | 180 | 400 | 30 | 125 HV | 14 % IACS |
Quarter hard | Light temper for stampings that still need moderate bending but a bit more stiffness than soft. | 380 | 500 | 15 | 147 HB | 13.5 % IACS |
Half hard | Balanced temper for connector contacts formed with generous bend radii. | 480 | 590 | 8 | 171 HB | 13.2 % IACS |
H04Default Full hard | Standard stocked condition for contact wire, pins and slip-ring brushes needing wear resistance. | 620 | 700 | 3 | 215 HV | 13 % IACS |
H08This page Spring hard | Highest strength temper for fine contact springs and probe wires; almost no formability left. | 760 | 820 | 1.5 | 21 HRC | 12.8 % IACS |
What is AuNi-H08?
AuNi-H08 is AuNi supplied in the H08 condition — highest strength temper for fine contact springs and probe wires; almost no formability left. AuNi-H08 has a yield strength of 760 MPa (110 ksi) and a tensile strength of 820 MPa (119 ksi) — stronger than 100% of precious metal grades. Elongation at break is 1.5% and the elastic modulus is 96 GPa (13.9 Msi). AuNi-H08 has a density of 18.3 g/cm³ (0.661 lb/in³), heavier than 89% of precious metal grades. It melts at 955°C (1,751 °F). H04 is the default condition FabDigit quotes; H08 is available on request or by drawing note.
Advantages
- High strength — 760 MPa (110 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
- Good corrosion resistance — 96/100, better than 85% of precious metal grades
Limitations
- Limited ductility — 1.5%, worse than 99% of precious metal grades
- High embodied carbon — 24,000 kg CO₂/kg, worse than 98% of precious metal grades
- Limited formability — 35/100, worse than 92% of precious metal grades
- Heavy — 18.3 g/cm³ (0.661 lb/in³), worse than 89% of precious metal grades
AuNi-H08 properties
Typical room-temperature values for AuNi-H08; 21 are specific to this condition. Other listed values are AuNi reference data and may not represent this condition. Bars are the position among precious metal grades.
Physical3
AuNi-H08 has a density of 18.3 g/cm³ (0.661 lb/in³), heavier than 89% of precious metal grades. It melts at 955°C (1,751 °F).
Mechanical10
AuNi-H08 has a yield strength of 760 MPa (110 ksi) and a tensile strength of 820 MPa (119 ksi) — stronger than 100% of precious metal grades. Elongation at break is 1.5% and the elastic modulus is 96 GPa (13.9 Msi).
Thermal6
AuNi-H08 is rated for continuous service to 300°C (572 °F). It conducts heat at 57 W/m·K (32.9 BTU/hr·ft·°F), worse than 74% of precious metal grades. Thermal expansion is 14.2 µm/m·K (7.89 µin/in·°F).
Electrical3
AuNi-H08 conducts electricity at 12.8 % IACS, worse than 73% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (96/100), better than 85% of precious metal grades.
Sustainability4
Producing a kilogram of AuNi-H08 takes about 240,000 MJ of energy and emits 24,000 kg of CO₂ — more than 91% of precious metal grades. Typical recycled content is 30%.
Manufacturability8
AuNi-H08's machinability is good (55/100, better than 86% of precious metal grades); weldability good (68/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with AuNi-H08
Is AuNi easy to machine?
Gummy and expensive — use sharp, polished-flute carbide or diamond tools, high speed, light feed, oil mist, and capture every chip for refining.
Can AuNi be welded?
Resistance, percussion and laser welding of contact rivets/wires to Cu-alloy carriers is routine; avoid fusion welding to steels which forms brittle intermetallics.
Can AuNi be formed, bent or molded?
Anneal at 600–750 °C in inert or reducing atmosphere, then cold roll/draw with >70 % reduction possible between anneals; hard tempers must be formed with generous radii (≥2t).
What surface finishes work on AuNi?
Not anodizable; finish by burnishing, diamond turning or fine polishing — or apply as an electrodeposited hard-gold layer over 1–2 µm Ni underplate to block copper diffusion.
AuNi 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 |
|---|---|---|
| Nisolid-solution hardener; raises hardness and wear life | 4.5 – 5.5 | 5 |
| Cuimpurity limit | ≤ 0.05 | — |
| Feimpurity limit | ≤ 0.03 | — |
| Agimpurity limit | ≤ 0.05 | — |
| Other, totaltotal residuals | ≤ 0.1 | — |
| Aubalance, ≥94.9 % typical (Au 950 fineness) | balance | — |
AuNi-H08 — frequently asked
What is AuNi-H08 used for?
AuNi-H08 is typically used for reed switch contacts, connector plating overlays, low-level signal relay contacts and precision instrument connectors. In short: hardest tarnish-free contact gold; dry-circuit signal reliability; thin-overlay cost control.
What is the yield strength of AuNi-H08?
AuNi-H08 has a typical yield strength of 760 MPa (110 ksi) and a tensile strength of 820 MPa (119 ksi) — stronger than 100% of precious metal grades. Strength varies by condition: see the 6 listed tempers.
Is AuNi-H08 easy to machine?
Reasonably — machinability is rated good (55/100, better than 86% of precious metal grades). Gummy and expensive — use sharp, polished-flute carbide or diamond tools, high speed, light feed, oil mist, and capture every chip for refining.
Can AuNi-H08 be welded?
Yes — weldability is rated good (68/100). Resistance, percussion and laser welding of contact rivets/wires to Cu-alloy carriers is routine; avoid fusion welding to steels which forms brittle intermetallics.
What surface finishes work on AuNi-H08?
Not anodizable; finish by burnishing, diamond turning or fine polishing — or apply as an electrodeposited hard-gold layer over 1–2 µm Ni underplate to block copper diffusion.
Can AuNi-H08 be formed, bent or molded?
Anneal at 600–750 °C in inert or reducing atmosphere, then cold roll/draw with >70 % reduction possible between anneals; hard tempers must be formed with generous radii (≥2t).
What is the maximum service temperature of AuNi-H08?
AuNi-H08 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 AuNi-H04 and AuNi Cast?
H04 is the default condition — standard stocked condition for contact wire, pins and slip-ring brushes needing wear resistance. Cast: intermediate form from the refinery before rolling/drawing; not used in service. Yield strength is 620 MPa in H04 versus 150 MPa in Cast.
Sources
- ASTM B541 — Standard Specification for Gold Electrical Contact Alloy — ASTM International (2018)
- ASTM B488 — Electrodeposited Coatings of Gold for Engineering Uses — ASTM International (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Precious Metals) — ASM International (1990)
- ASM Alloy Phase Diagrams — Au-Ni system — ASM International (2016)
- Precious-metal electrical contact alloy wire and strip data (Deringer-Ney / Materion / Heraeus style datasheets) — 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.