Nickel Alloy BNi-7
UNS N99710 · ISO B-Ni7
BNi-7 is a nickel-chromium-phosphorus brazing filler metal (UNS N99710) from the AWS A5.8 family, combining phosphorus self-fluxing action with chromium for better corrosion resistance than BNi-6.
Reference datasheet — BNi-7 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.
BNi-7 tempers and conditions
BNi-7 is supplied in one standard condition, AS_BRAZED.
Supply forms, finishes and certifications
Ways BNi-7 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
FOIL | Amorphous foil / ribbon | Supply form |
PREFORM | Sintered preform / transfer tape | Supply form |
PASTE | Powder in organic binder for dispensing/screening | Printing process |
POWDERDefault | Gas-atomized braze powder | Printing process |
What is BNi-7?
BNi-7 is a nickel-chromium-phosphorus brazing filler metal (UNS N99710) from the AWS A5.8 family, combining phosphorus self-fluxing action with chromium for better corrosion resistance than BNi-6. It brazes at 950-1065 C in vacuum or dry hydrogen, suits stainless steel and instrument hardware, and is supplied as powder, paste, amorphous foil and preform with a deposit density of 7.6 g/cm3. The deposit contains hard, brittle phosphides and cannot be fusion welded or machined conventionally. Long high-temperature holds drive phosphorus diffusion into the parent metal and form an embrittled layer. BNi-7 has a density of 7.6 g/cm³ (0.275 lb/in³), lighter than 99% of nickel alloy grades. It melts at 890°C (1,634 °F). BNi-7 has a tensile strength of 420 MPa (60.9 ksi), weaker than 97% of nickel alloy grades. Elongation at break is 1% and the elastic modulus is 175 GPa (25.4 Msi).
What is BNi-7 used for?
- stainless steel brazing
- corrosion-resistant instrument fittings
- low-temperature furnace brazing
Limitations
- Limited ductility — 1%, worse than 98% of nickel alloy grades
- Difficult to machine — 8/100, worse than 96% of nickel alloy grades
- Hard to polish — 55/100, worse than 95% of nickel alloy grades
- Difficult to weld — 10/100, worse than 94% of nickel alloy grades
- Low stiffness — 175 GPa (25.4 Msi), worse than 90% of nickel alloy grades
BNi-7 properties
Typical room-temperature values; bars are the position among nickel alloy grades.
Physical3
BNi-7 has a density of 7.6 g/cm³ (0.275 lb/in³), lighter than 99% of nickel alloy grades. It melts at 890°C (1,634 °F).
Mechanical8
BNi-7 has a tensile strength of 420 MPa (60.9 ksi), weaker than 97% of nickel alloy grades. Elongation at break is 1% and the elastic modulus is 175 GPa (25.4 Msi).
Thermal5
BNi-7 is rated for continuous service to 700°C (1,292 °F). It conducts heat at 12 W/m·K (6.93 BTU/hr·ft·°F), better than 65% of nickel alloy grades. Thermal expansion is 13 µm/m·K (7.22 µin/in·°F).
Electrical2
BNi-7 has an electrical resistivity of 1.2×10⁻⁶ Ω·m.
Chemical & Environmental2
Corrosion resistance is good (60/100), worse than 89% of nickel alloy grades.
Sustainability4
Producing a kilogram of BNi-7 takes about 135 MJ of energy and emits 13 kg of CO₂ — less than 84% of nickel alloy grades. Typical recycled content is 10%.
Manufacturability4
BNi-7's machinability is not recommended (8/100, worse than 96% of nickel alloy grades); weldability not recommended (10/100).
Common Calculations4
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 nickel alloy family
Yield strength against density for every nickel alloy grade FabDigit runs. BNi-7 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with BNi-7
Is BNi-7 easy to machine?
The solidified filler contains hard, brittle phosphides and is effectively unmachinable; grind excess braze off with diamond or aluminium oxide wheels. Avoid turning or milling across the fillet.
Can BNi-7 be welded?
Not usable as a fusion welding filler. Re-melting the braze seam or arc contact produces phosphorus segregation cracks, so repair by re-brazing.
Can BNi-7 be formed, bent or molded?
Supplied as powder, paste, amorphous foil or preform; the amorphous foil can be sheared and blanked into shapes. Hold joint clearance at 0.025-0.075 mm for best capillary fill.
BNi-7 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 |
|---|---|---|
| Cr | 13 – 15 | 14 |
| Pself-fluxing element, forms low-melting eutectic | 9.7 – 10.5 | 10.1 |
| C | ≤ 0.06 | |
| Si | ≤ 0.1 | |
| Blow boron, avoids diffusion attack in nuclear/thin-wall parts | ≤ 0.01 | |
| Fe | ≤ 0.2 | |
| S | ≤ 0.02 | |
| Co | ≤ 0.1 | |
| Al | ≤ 0.05 | |
| Ti | ≤ 0.05 | |
| Zr | ≤ 0.05 | |
| Se | ≤ 0.01 | |
| Others (total) | ≤ 0.5 | |
| Ni | balance |
What surface finishes work on BNi-7?
Joints are ready for service after brazing at 950-1065 C in a vacuum or dry hydrogen furnace. Seams can be plated or passivated, but extended high-temperature holds increase phosphorus diffusion into the parent metal and form a brittle layer.
Surface treatments FabDigit runs on nickel alloy parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Nickel Alloy BNi-7 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- N99710
- ISO
- B-Ni7
How much does BNi-7 cost?
BNi-7 is a high-cost nickel alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
BNi-7 — frequently asked
What is BNi-7 used for?
BNi-7 is typically used for stainless steel brazing, corrosion-resistant instrument fittings and low-temperature furnace brazing. In short: chromium-bearing self-fluxing braze; better corrosion than BNi-6; amorphous foil available.
What is the tensile strength of BNi-7?
BNi-7 has a typical tensile strength of 420 MPa (60.9 ksi) — weaker than 97% of nickel alloy grades.
Is BNi-7 easy to machine?
Not especially — machinability is rated not recommended (8/100, worse than 96% of nickel alloy grades). The solidified filler contains hard, brittle phosphides and is effectively unmachinable; grind excess braze off with diamond or aluminium oxide wheels. Avoid turning or milling across the fillet.
Can BNi-7 be welded?
Not readily — weldability is rated not recommended (10/100). Not usable as a fusion welding filler. Re-melting the braze seam or arc contact produces phosphorus segregation cracks, so repair by re-brazing.
What surface finishes work on BNi-7?
Joints are ready for service after brazing at 950-1065 C in a vacuum or dry hydrogen furnace. Seams can be plated or passivated, but extended high-temperature holds increase phosphorus diffusion into the parent metal and form a brittle layer.
Can BNi-7 be formed, bent or molded?
Supplied as powder, paste, amorphous foil or preform; the amorphous foil can be sheared and blanked into shapes. Hold joint clearance at 0.025-0.075 mm for best capillary fill.
What is the maximum service temperature of BNi-7?
BNi-7 is rated for continuous use to about 700°C (1,292 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does BNi-7 cost?
BNi-7 is a high-cost nickel alloy ($$$$), 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 — American Welding Society (2019)
- GB/T 10859 (2008)
- ASM Handbook Vol.6 — Welding, Brazing and Soldering (Brazing Filler Metals) — ASM International (1993)
- Nickel braze filler metal powder & amorphous foil datasheets (BNi-7 / N99710) — Wall Colmonoy / Lucas-Milhaupt / Metglas (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.