Cobalt-Chrome Alloy AWS BCo-1
UNS R39001
AWS BCo-1 (UNS R39001) is a cobalt-chromium-tungsten brazing filler metal alloyed with boron and silicon, with a melting point of 1121 °C and a density of 8.4 g/cm³.
Reference datasheet — AWS BCo-1 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
AWS BCo-1 tempers and conditions
AWS BCo-1 is supplied in 2 conditions, soft to hard.
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
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 |
Supply forms, finishes and certifications
Ways AWS BCo-1 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
PREFORM | Sintered/pressed preform | Supply form |
PASTE | Braze paste | Printing process |
POWDERDefault | Atomized powder | Printing process |
TAPE | Transfer tape / flexible sheet preform | Printing process |
What is AWS BCo-1?
AWS BCo-1 (UNS R39001) is a cobalt-chromium-tungsten brazing filler metal alloyed with boron and silicon, with a melting point of 1121 °C and a density of 8.4 g/cm³. It is used for vacuum or dry-hydrogen brazing of cobalt- and nickel-base high-temperature assemblies, and because boron and silicon make the alloy unworkable it is supplied only as atomised powder, paste, transfer tape or pressed/sintered preforms, in as-brazed or diffusion-treated condition. Joints serve to about 980 °C, but the as-brazed seam is hard and brittle, cannot be fusion welded, and demands 0.025–0.075 mm clearance with oxide-free surfaces. AWS BCo-1 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).
What is AWS BCo-1 used for?
- hardfacing overlays
- valve seats
- pump sleeves
- wear plates
Advantages
- High service temperature — 980°C (1,796 °F), better than 93% of cobalt-chrome alloy grades
Limitations
- Difficult to weld — 10/100, worse than 100% of cobalt-chrome alloy grades
- Needs corrosion protection — 68/100, worse than 80% of cobalt-chrome alloy grades
AWS BCo-1 properties
Typical room-temperature values; bars are the position among cobalt-chrome alloy grades.
Physical3
AWS BCo-1 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 is rated for continuous service to 980°C (1,796 °F). It conducts heat at 13 W/m·K (7.51 BTU/hr·ft·°F), worse than 68% of cobalt-chrome alloy grades. Thermal expansion is 13.8 µm/m·K (7.67 µin/in·°F).
Electrical2
AWS BCo-1 has an electrical resistivity of 1.1×10⁻⁶ Ω·m.
Chemical & Environmental2
Corrosion resistance is good (68/100), worse than 80% of cobalt-chrome alloy grades.
Sustainability3
Producing a kilogram of AWS BCo-1 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's machinability is not recommended (5/100, worse than 82% of cobalt-chrome alloy grades); weldability not recommended (10/100); formability not recommended (5/100).
Common Calculations1
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the cobalt-chrome alloy family
Yield strength against density for every cobalt-chrome alloy grade FabDigit runs. AWS BCo-1 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with AWS BCo-1
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.
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 |
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.
Equivalent designations
Standards and trade names that resolve to Cobalt-Chrome Alloy AWS BCo-1 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- R39001
- Also called
- AWS A5.21 BCo-1
How much does AWS BCo-1 cost?
AWS BCo-1 is a high-cost cobalt-chrome alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
AWS BCo-1 — frequently asked
What is AWS BCo-1 used for?
AWS BCo-1 is typically used for hardfacing overlays, valve seats, pump sleeves and wear plates. In short: cobalt-base brazing filler; 980 °C joint service; not a welding consumable.
Is AWS BCo-1 easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 82% of cobalt-chrome alloy grades). The alloy is never machined as a bulk product; the as-brazed seam is hard and brittle — dress only by grinding with SiC/diamond wheels.
Can AWS BCo-1 be welded?
Not readily — weldability is rated not recommended (10/100). Not a welding consumable: fusion welding of the boron-bearing seam cracks; repair by re-brazing in a fresh furnace cycle.
What surface finishes work on AWS BCo-1?
Vacuum or dry-hydrogen brazing at 1149–1204 °C with 0.025–0.075 mm joint clearance and scrupulously clean, oxide-free surfaces; add a post-braze diffusion cycle to raise remelt temperature and reduce seam brittleness.
Can AWS BCo-1 be formed, bent or molded?
B and Si make the alloy unworkable, so it is atomized to powder and supplied as paste, transfer tape or pressed/sintered preforms.
What is the maximum service temperature of AWS BCo-1?
AWS BCo-1 is rated for continuous use to about 980°C (1,796 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does AWS BCo-1 cost?
AWS BCo-1 is a high-cost cobalt-chrome alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.