Nickel Alloy BNi-8: Properties, Machinability & Uses

BNi-8 tempers and conditions

BNi-8 is supplied in one standard condition, AS-BRAZED.

AS-BRAZED

Supply forms, finishes and certifications

Ways BNi-8 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.

Option	What it is	Type
PASTE	Powder in organic binder, syringe/cartridge	Printing process
POWDERDefault	Gas-atomised, -140/+325 or -325 mesh	Printing process
TAPE	Flexible tape / preform	Printing process

What is BNi-8?

BNi-8 is a nickel-manganese-silicon brazing filler metal (UNS N99800) in the AWS A5.8 family, free of both boron and phosphorus so that brittle boride and phosphide phases are avoided in the joint. It is specified for nickel-alloy and stainless assemblies that must stay ductile or be formed after brazing; melting point is 980 C and deposit density 8.1 g/cm3, supplied as powder, paste, tape and preform. Manganese evaporates in hard vacuum, so brazing needs an argon partial pressure, and the fillet is still hard enough to require grinding rather than machining. BNi-8 has a density of 8.1 g/cm³ (0.293 lb/in³), lighter than 80% of nickel alloy grades. It melts at 980°C (1,796 °F). BNi-8 has a tensile strength of 420 MPa (60.9 ksi), weaker than 97% of nickel alloy grades. Elongation at break is 2% and the elastic modulus is 180 GPa (26.1 Msi).

What is BNi-8 used for?

Ductile nickel alloy joints
Components requiring post-braze forming
Boron-free joints for nuclear and neutron-sensitive parts
Stainless steel brazed assemblies
Thin-section heat exchanger joints
Instrument and vacuum hardware

Advantages

Conducts heat well — 15 W/m·K (8.67 BTU/hr·ft·°F), better than 81% of nickel alloy grades

Limitations

Limited ductility — 2%, worse than 95% of nickel alloy grades
Needs corrosion protection — 40/100, worse than 95% of nickel alloy grades
Difficult to weld — 10/100, worse than 94% of nickel alloy grades
Low stiffness — 180 GPa (26.1 Msi), worse than 85% of nickel alloy grades

BNi-8 properties

Typical room-temperature values; bars are the position among nickel alloy grades.

Physical3

BNi-8 has a density of 8.1 g/cm³ (0.293 lb/in³), lighter than 80% of nickel alloy grades. It melts at 980°C (1,796 °F).

Density8.1 g/cm³0.29 lb/in³

Melting Point (Solidus)980°C1,796 °F

Liquidus Temperature1,010°C1,850 °F

Mechanical6

BNi-8 has a tensile strength of 420 MPa (60.9 ksi), weaker than 97% of nickel alloy grades. Elongation at break is 2% and the elastic modulus is 180 GPa (26.1 Msi).

Elastic (Young's) Modulus180 GPa26.1 Msi

Poisson's Ratio0.31

Tensile Strength (Ultimate)420 MPa60.9 ksi

Elongation at Break2%

Shear Strength200 MPa29 ksi

Hardness, Vickers350 HV

Thermal5

BNi-8 is rated for continuous service to 600°C (1,112 °F). It conducts heat at 15 W/m·K (8.67 BTU/hr·ft·°F), better than 81% of nickel alloy grades. Thermal expansion is 14.5 µm/m·K (8.06 µin/in·°F).

Thermal Conductivity15 W/m·K8.7 BTU/hr·ft·°F

Specific Heat Capacity450 J/kg·K0.11 BTU/lb·°F

Thermal Expansion (CTE, 20–100 °C)14.5 µm/m·K8.1 µin/in·°F

Max Service Temperature (continuous)600°C1,112 °F

Min Service Temperature-196°C-321 °F

Electrical2

BNi-8 has an electrical resistivity of 1.1×10⁻⁶ Ω·m.

Electrical Resistivity1.1×10⁻⁶ Ω·m43.3 µΩ·in

Magnetic Responseweakly magnetic — high Mn content suppresses the Ni Curie point close to or below room temperature

Chemical & Environmental2

Corrosion resistance is fair (40/100), worse than 95% of nickel alloy grades.

Corrosion ResistanceFair40/100

Chemical Resistance SummaryAdequate in mild atmospheres, water and many organics; chromium-free so it oxidises above ~650 °C and is attacked by oxidising acids, sulphur-bearing hot gases and halides — not for aggressive corrosion service.

Sustainability4

Producing a kilogram of BNi-8 takes about 150 MJ of energy and emits 12 kg of CO₂ — less than 68% of nickel alloy grades. Typical recycled content is 15%.

Embodied Energy (primary production)150 MJ/kg64,488 BTU/lb

Embodied Carbon (primary production)12 kg CO₂/kg

Embodied Water250 L/kg30 gal/lb

Typical Recycled Content15%

Manufacturability3

BNi-8's machinability is poor (15/100, worse than 76% of nickel alloy grades); weldability not recommended (10/100).

MachinabilityPoor15/100

WeldabilityNot recommended10/100

Brazeability / SolderabilityExcellent88/100

Common Calculations4

Specific Strength (UTS / density)calculated52 kN·m/kg

Specific Stiffness (E / density)calculated22.2 MN·m/kg

Thermal Diffusivitycalculated4.1 mm²/s

Thermal Shock Resistance Indexcalculated2

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-8 is highlighted; hover a dot for its name, or open the interactive family chart.

Working with BNi-8

Is BNi-8 easy to machine?

Solidified fillets are hard and brittle — remove excess by grinding or EDM rather than turning/milling.

Can BNi-8 be welded?

Not a structural weld filler; fusion welding over a BNi-8 joint remelts it and causes cracking, so keep weld heat away from brazed seams.

Can BNi-8 be formed, bent or molded?

Supplied only as powder, paste, tape or sintered preform; joint gap of 0.05–0.13 mm gives best capillary fill.

BNi-8 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
Mn	21.5 – 24.5	23
Si	6 – 8	7
Cu	4 – 5	4.5
C	≤ 0.1
Pintentionally P-free	≤ 0.02
S	≤ 0.02
Bintentionally B-free	≤ 0.03
Al	≤ 0.05
Ti	≤ 0.05
Zr	≤ 0.05
Other, total	≤ 0.5
Ni	balance

What surface finishes work on BNi-8?

Braze in vacuum with 0.1–1 mbar argon partial pressure to suppress Mn evaporation and furnace contamination; grit-blast and passivate stainless assemblies afterwards.

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

Plasma Spray

Equivalent designations

Standards and trade names that resolve to Nickel Alloy BNi-8 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.

UNS: N99800
ISO: B-Ni8

Other Inconel & Incoloy (Ni-Cr-Fe) nickel alloy grades

Closest nickel alloy grades by properties

Compare BNi-8 with…

Benchmark BNi-8 against the top 3 neighbours

How much does BNi-8 cost?

BNi-8 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-8 — frequently asked

What is BNi-8 used for?

BNi-8 is typically used for ductile nickel alloy joints, components requiring post-braze forming, boron-free joints for nuclear and neutron-sensitive parts, stainless steel brazed assemblies, thin-section heat exchanger joints and instrument and vacuum hardware. In short: boron and phosphorus free; most ductile nickel braze; needs argon partial pressure.

What is the tensile strength of BNi-8?

BNi-8 has a typical tensile strength of 420 MPa (60.9 ksi) — weaker than 97% of nickel alloy grades.

Is BNi-8 easy to machine?

Not especially — machinability is rated poor (15/100, worse than 76% of nickel alloy grades). Solidified fillets are hard and brittle — remove excess by grinding or EDM rather than turning/milling.

Can BNi-8 be welded?

Not readily — weldability is rated not recommended (10/100). Not a structural weld filler; fusion welding over a BNi-8 joint remelts it and causes cracking, so keep weld heat away from brazed seams.