Cobalt-Chrome Alloy AWS BCo-1 AS-BRAZED
Heat-treated state
UNS R39001
Property set for the solidified seam straight out of the braze cycle — hardest and most brittle condition.
Values for the AS-BRAZED condition
Other AWS BCo-1 tempers and conditions
AWS BCo-1 is listed in 2 conditions; see the grade overview at AWS BCo-1.
- AS-BRAZED
- DIFFUSION
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AS-BRAZEDThis page As-brazed joint (1149–1204 °C, vacuum or dry H₂, no diffusion cycle) | Property set for the solidified seam straight out of the braze cycle — hardest and most brittle condition. | 400 | 450 | 1 | 55 HRC | 1.5 % IACS |
Brazed + diffusion heat treatment (hold near/above braze temperature to homogenize B/Si) | Pick when joint ductility, remelt temperature and stress-rupture life must be raised for hot-section service. | 470 | 620 | 4 | 43 HRC | 1.7 % IACS |
What is AWS BCo-1 AS-BRAZED?
AWS BCo-1 AS-BRAZED is AWS BCo-1 heat treated to AS-BRAZED — property set for the solidified seam straight out of the braze cycle — hardest and most brittle condition. AWS BCo-1 AS-BRAZED has a density of 8.4 g/cm³ (0.303 lb/in³), lighter than 57% of cobalt-chrome alloy grades. It melts at 1,121°C (2,050 °F).
Advantages
- High service temperature — 950°C (1,742 °F), better than 89% of cobalt-chrome alloy grades
Limitations
- Difficult to weld — 5/100, worse than 100% of cobalt-chrome alloy grades
- Needs corrosion protection — 65/100, worse than 86% of cobalt-chrome alloy grades
- Poor heat conductor — 12 W/m·K (6.93 BTU/hr·ft·°F), worse than 82% of cobalt-chrome alloy grades
AWS BCo-1 AS-BRAZED properties
Typical room-temperature values for AWS BCo-1 AS-BRAZED; 22 are specific to this condition. Other listed values are AWS BCo-1 reference data and may not represent this condition. Bars are the position among cobalt-chrome alloy grades.
Physical3
AWS BCo-1 AS-BRAZED has a density of 8.4 g/cm³ (0.303 lb/in³), lighter than 57% of cobalt-chrome alloy grades. It melts at 1,121°C (2,050 °F).
Mechanical3
Thermal5
AWS BCo-1 AS-BRAZED is rated for continuous service to 950°C (1,742 °F). It conducts heat at 12 W/m·K (6.93 BTU/hr·ft·°F), worse than 82% of cobalt-chrome alloy grades. Thermal expansion is 13.8 µm/m·K (7.67 µin/in·°F).
Electrical2
AWS BCo-1 AS-BRAZED has an electrical resistivity of 1.15×10⁻⁶ Ω·m.
Chemical & Environmental2
Corrosion resistance is good (65/100), worse than 86% of cobalt-chrome alloy grades.
Sustainability3
Producing a kilogram of AWS BCo-1 AS-BRAZED takes about 155 MJ of energy and emits 12 kg of CO₂ — more than 52% of cobalt-chrome alloy grades. Typical recycled content is 10%.
Manufacturability4
AWS BCo-1 AS-BRAZED's machinability is not recommended (5/100, worse than 82% of cobalt-chrome alloy grades); weldability not recommended (5/100); formability not recommended (2/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with AWS BCo-1 AS-BRAZED
Is AWS BCo-1 easy to machine?
The alloy is never machined as a bulk product; the as-brazed seam is hard and brittle — dress only by grinding with SiC/diamond wheels.
Can AWS BCo-1 be welded?
Not a welding consumable: fusion welding of the boron-bearing seam cracks; repair by re-brazing in a fresh furnace cycle.
Can AWS BCo-1 be formed, bent or molded?
B and Si make the alloy unworkable, so it is atomized to powder and supplied as paste, transfer tape or pressed/sintered preforms.
What surface finishes work on AWS BCo-1?
Vacuum or dry-hydrogen brazing at 1149–1204 °C with 0.025–0.075 mm joint clearance and scrupulously clean, oxide-free surfaces; add a post-braze diffusion cycle to raise remelt temperature and reduce seam brittleness.
AWS BCo-1 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 |
|---|---|---|
| Croxidation/sulfidation resistance | 18 – 20 | 19 |
| Ni | 16 – 18 | 17 |
| Wsolid-solution strengthening | 3 – 4 | 4 |
| Simelting point depressant | 7.5 – 8.5 | 8 |
| Bmelting point depressant; diffuses into base metal | 0.7 – 0.9 | 0.8 |
| C | 0.35 – 0.45 | 0.4 |
| Fe | ≤ 1 | — |
| other (total)total of all other elements, max | ≤ 0.5 | — |
| Cobalance, ~ 50 % | balance | — |
AWS BCo-1 AS-BRAZED — frequently asked
What is AWS BCo-1 AS-BRAZED used for?
AWS BCo-1 AS-BRAZED is typically used for hardfacing overlays, valve seats, pump sleeves and wear plates. In short: cobalt-base brazing filler; 980 °C joint service; not a welding consumable.
Is AWS BCo-1 AS-BRAZED easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 82% of cobalt-chrome alloy grades). The alloy is never machined as a bulk product; the as-brazed seam is hard and brittle — dress only by grinding with SiC/diamond wheels.
Can AWS BCo-1 AS-BRAZED be welded?
Not readily — weldability is rated not recommended (5/100). Not a welding consumable: fusion welding of the boron-bearing seam cracks; repair by re-brazing in a fresh furnace cycle.
What surface finishes work on AWS BCo-1 AS-BRAZED?
Vacuum or dry-hydrogen brazing at 1149–1204 °C with 0.025–0.075 mm joint clearance and scrupulously clean, oxide-free surfaces; add a post-braze diffusion cycle to raise remelt temperature and reduce seam brittleness.
Can AWS BCo-1 AS-BRAZED be formed, bent or molded?
B and Si make the alloy unworkable, so it is atomized to powder and supplied as paste, transfer tape or pressed/sintered preforms.
What is the maximum service temperature of AWS BCo-1 AS-BRAZED?
AWS BCo-1 AS-BRAZED is rated for continuous use to about 950°C (1,742 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- AWS A5.8/A5.8M — Specification for Filler Metals for Brazing and Braze Welding (BCo-1, UNS R39001) — American Welding Society (2019)
- ASM Handbook Vol.6 — Welding, Brazing and Soldering (cobalt-base brazing filler metals) — ASM International (1993)
- ASM Specialty Handbook: Nickel, Cobalt and Their Alloys — ASM International (2000)
- High-temperature braze powder / paste datasheets (Co-base BCo-1 type) — Höganäs / Wall Colmonoy / Lucas-Milhaupt (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.