Precious Metal BAu-4 AS-BRAZED
Heat-treated state
UNS P00820
Reference condition for joint design allowables: lap-shear and tensile capability of the finished braze on superalloy or 300-series stainless.
Values for the AS-BRAZED condition
What is BAu-4 AS-BRAZED?
BAu-4 AS-BRAZED is BAu-4 heat treated to AS-BRAZED — reference condition for joint design allowables: lap-shear and tensile capability of the finished braze on superalloy or 300-series stainless. BAu-4 AS-BRAZED has a yield strength of 210 MPa (30.5 ksi) and a tensile strength of 400 MPa (58 ksi) — stronger than 61% of precious metal grades. Elongation at break is 25% and the elastic modulus is 105 GPa (15.2 Msi). BAu-4 AS-BRAZED has a density of 15.9 g/cm³ (0.574 lb/in³), heavier than 81% of precious metal grades. It melts at 950°C (1,742 °F).
Advantages
- High service temperature — 800°C (1,472 °F), better than 90% of precious metal grades
Limitations
- Low electrical conductivity — 7 % IACS, worse than 89% of precious metal grades
- High embodied carbon — 14,000 kg CO₂/kg, worse than 88% of precious metal grades
- Heavy — 15.9 g/cm³ (0.574 lb/in³), worse than 81% of precious metal grades
BAu-4 AS-BRAZED properties
Typical room-temperature values for BAu-4 AS-BRAZED; 4 are specific to this condition. Other listed values are BAu-4 reference data and may not represent this condition. Bars are the position among precious metal grades.
Physical3
BAu-4 AS-BRAZED has a density of 15.9 g/cm³ (0.574 lb/in³), heavier than 81% of precious metal grades. It melts at 950°C (1,742 °F).
Mechanical9
BAu-4 AS-BRAZED has a yield strength of 210 MPa (30.5 ksi) and a tensile strength of 400 MPa (58 ksi) — stronger than 61% of precious metal grades. Elongation at break is 25% and the elastic modulus is 105 GPa (15.2 Msi).
Thermal6
BAu-4 AS-BRAZED is rated for continuous service to 800°C (1,472 °F). It conducts heat at 60 W/m·K (34.7 BTU/hr·ft·°F), worse than 72% of precious metal grades. Thermal expansion is 15.5 µm/m·K (8.61 µin/in·°F).
Electrical3
BAu-4 AS-BRAZED conducts electricity at 7 % IACS, worse than 89% of precious metal grades.
Chemical & Environmental2
Corrosion resistance is excellent (90/100), better than 69% of precious metal grades.
Sustainability4
Producing a kilogram of BAu-4 AS-BRAZED takes about 205,000 MJ of energy and emits 14,000 kg of CO₂ — more than 87% of precious metal grades. Typical recycled content is 45%.
Manufacturability6
BAu-4 AS-BRAZED's machinability is fair (35/100, worse than 73% of precious metal grades); weldability fair (40/100); formability very good (75/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with BAu-4 AS-BRAZED
Is BAu-4 easy to machine?
Soft and gummy — use sharp, polished carbide or HSS tooling, light cuts and full swarf capture for precious-metal recovery.
Can BAu-4 be welded?
Not a structural weld alloy; joints are made by vacuum or dry-hydrogen furnace brazing at 950–1010 °C with short dwell to limit Ni erosion of thin sections.
Can BAu-4 be formed, bent or molded?
Excellent cold ductility — readily drawn to fine wire, rolled to <50 µm foil and stamped into preforms with interstage annealing.
What surface finishes work on BAu-4?
Braze fillets need no coating; light ultrasonic or acid cleaning removes flux/binder residues, and the joint takes a bright polish without plating.
BAu-4 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, per AWS A5.8 BAu-4 / UNS P00820 | 81.5 – 82.5 | 82 |
| Other (total)total of all other elements, including impurities | ≤ 0.15 | |
| Ni | balance |
BAu-4 AS-BRAZED — frequently asked
What is BAu-4 AS-BRAZED used for?
BAu-4 AS-BRAZED is typically used for jet engine component brazing, nickel superalloy joints, high-temperature vacuum furnace parts and turbine seal assemblies. In short: high-temperature BAu filler; oxidation-resistant Au-Ni braze; superalloy brazing standard.
What is the yield strength of BAu-4 AS-BRAZED?
BAu-4 AS-BRAZED has a typical yield strength of 210 MPa (30.5 ksi) and a tensile strength of 400 MPa (58 ksi) — stronger than 61% of precious metal grades.
Is BAu-4 AS-BRAZED easy to machine?
Not especially — machinability is rated fair (35/100, worse than 73% of precious metal grades). Soft and gummy — use sharp, polished carbide or HSS tooling, light cuts and full swarf capture for precious-metal recovery.
Can BAu-4 AS-BRAZED be welded?
With care — weldability is rated fair (40/100). Not a structural weld alloy; joints are made by vacuum or dry-hydrogen furnace brazing at 950–1010 °C with short dwell to limit Ni erosion of thin sections.
What surface finishes work on BAu-4 AS-BRAZED?
Braze fillets need no coating; light ultrasonic or acid cleaning removes flux/binder residues, and the joint takes a bright polish without plating.
Can BAu-4 AS-BRAZED be formed, bent or molded?
Excellent cold ductility — readily drawn to fine wire, rolled to <50 µm foil and stamped into preforms with interstage annealing.
What is the maximum service temperature of BAu-4 AS-BRAZED?
BAu-4 AS-BRAZED is rated for continuous use to about 800°C (1,472 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- AWS A5.8M/A5.8:2019 Specification for Filler Metals for Brazing and Braze Welding — American Welding Society (2019)
- ASM Handbook Vol.6 — Welding, Brazing and Soldering (Gold brazing filler metals) — ASM International (1993)
- Brazing Handbook, 5th ed. — American Welding Society (2007)
- Gold-nickel braze filler metal (Au-18Ni) product data — precious-metal braze producers (Materion / Umicore / ) (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.