Solder & Low-Melting Alloy Bi50Pb25Sn25
Bi50Pb25Sn25 is a leaded bismuth-tin fusible alloy with a melting range near 98–110 °C, supplied as ingot, wire, powder and as-cast shapes.
Reference datasheet — Bi50Pb25Sn25 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.
Values for the AS-CAST condition
Bi50Pb25Sn25 tempers and conditions
Bi50Pb25Sn25 is supplied in one standard condition, AS-CAST. AS-CAST is the default FabDigit quotes; the values on this page are for it.
Supply forms, finishes and certifications
Ways Bi50Pb25Sn25 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
Ingot | Ingot / bar stock for remelting | Supply form |
WIRE | Extruded/drawn wire or ribbon | Supply form |
POWDER | Atomized powder / shot | Printing process |
What is Bi50Pb25Sn25?
Bi50Pb25Sn25 is a leaded bismuth-tin fusible alloy with a melting range near 98–110 °C, supplied as ingot, wire, powder and as-cast shapes. It is used where a repeatable melt point below boiling water is required, for low-melt pattern casting, fusible safety elements and calibration work; as-cast values are 30 MPa tensile strength, 18 MPa yield, 35% elongation and 11 HB. Maximum service temperature is about 50 °C and the lead content excludes RoHS and food-contact applications, so lead-free Bi32.5In51Sn16.5 or Bi57Sn42Ag1 are the usual substitutes. Bi50Pb25Sn25 has a density of 9.7 g/cm³ (0.35 lb/in³), heavier than 70% of solder & low-melting alloy grades. It melts at 98°C (208 °F). Bi50Pb25Sn25 has a yield strength of 18 MPa (2.61 ksi) and a tensile strength of 30 MPa (4.35 ksi) — weaker than 77% of solder & low-melting alloy grades. Elongation at break is 35% and the elastic modulus is 25 GPa (3.63 Msi).
What is Bi50Pb25Sn25 used for?
- low-temp soldering (historic)
- pattern casting
- fusible safety devices
- thermometry calibration
Limitations
- Poor heat conductor — 17 W/m·K (9.82 BTU/hr·ft·°F), worse than 95% of solder & low-melting alloy grades
- Difficult to weld — 10/100, worse than 94% of solder & low-melting alloy grades
- Limited service temperature — 50°C (122 °F), worse than 93% of solder & low-melting alloy grades
- Low electrical conductivity — 4 % IACS, worse than 93% of solder & low-melting alloy grades
- Limited formability — 60/100, worse than 78% of solder & low-melting alloy grades
Bi50Pb25Sn25 properties
Typical room-temperature values for Bi50Pb25Sn25-AS-CAST; bars are the position among solder & low-melting alloy grades.
Physical3
Bi50Pb25Sn25 has a density of 9.7 g/cm³ (0.35 lb/in³), heavier than 70% of solder & low-melting alloy grades. It melts at 98°C (208 °F).
Mechanical10
Bi50Pb25Sn25 has a yield strength of 18 MPa (2.61 ksi) and a tensile strength of 30 MPa (4.35 ksi) — weaker than 77% of solder & low-melting alloy grades. Elongation at break is 35% and the elastic modulus is 25 GPa (3.63 Msi).
Thermal6
Bi50Pb25Sn25 is rated for continuous service to 50°C (122 °F). It conducts heat at 17 W/m·K (9.82 BTU/hr·ft·°F), worse than 95% of solder & low-melting alloy grades. Thermal expansion is 17 µm/m·K (9.44 µin/in·°F).
Electrical3
Bi50Pb25Sn25 conducts electricity at 4 % IACS, worse than 93% of solder & low-melting alloy grades.
Chemical & Environmental3
Corrosion resistance is fair (45/100), worse than 52% of solder & low-melting alloy grades.
Sustainability4
Producing a kilogram of Bi50Pb25Sn25 takes about 120 MJ of energy and emits 8.5 kg of CO₂ — less than 65% of solder & low-melting alloy grades. Typical recycled content is 60%.
Manufacturability8
Bi50Pb25Sn25's machinability is fair (40/100, better than 65% of solder & low-melting alloy grades); weldability not recommended (10/100); formability good (60/100).
Common Calculations5
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 solder & low-melting alloy family
Yield strength against density for every solder & low-melting alloy grade FabDigit runs. Bi50Pb25Sn25 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Bi50Pb25Sn25
Is Bi50Pb25Sn25 easy to machine?
Machines only with very sharp high-rake tools, light cuts and flood coolant — the alloy smears and creeps; freeze-chucking or wax support is common.
Can Bi50Pb25Sn25 be welded?
Not weldable in any conventional sense; parts are joined by remelting the alloy itself or by soldering with the same composition (rosin flux, 130–160 °C bath).
Can Bi50Pb25Sn25 be formed, bent or molded?
Ideal for gravity/dip casting into silicone, plaster or steel moulds at 130–160 °C; very low shrinkage reproduces fine detail, but overheating above ~250 °C causes dross and dezincification of brass tooling.
Bi50Pb25Sn25 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 |
|---|---|---|
| Biprincipal constituent; gives low melting point and near-zero solidification shrinkage | 49 – 51 | 50 |
| Pbsome historical recipes use 28 % Pb / 22 % Sn | 24 – 28 | 25 |
| Cdimpurity limit; Cd-free composition | ≤ 0.05 | |
| Sbimpurity | ≤ 0.1 | |
| Cuimpurity | ≤ 0.05 | |
| Znimpurity, harmful to wetting | ≤ 0.01 | |
| Feimpurity | ≤ 0.02 | |
| Sn | ≥ 22 (balance) |
What surface finishes work on Bi50Pb25Sn25?
Cannot be anodized or hard-plated; leave as-cast or lightly scrape/burnish. Surfaces dull in humid air; lead content requires handling and disposal controls and rules out RoHS/food-contact use.
Equivalent designations
Standards and trade names that resolve to Solder & Low-Melting Alloy Bi50Pb25Sn25 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Also called
- Rose's Metal
How much does Bi50Pb25Sn25 cost?
Bi50Pb25Sn25 is a high-cost solder & low-melting 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.
Bi50Pb25Sn25 — frequently asked
What is Bi50Pb25Sn25 used for?
Bi50Pb25Sn25 is typically used for low-temp soldering (historic), pattern casting, fusible safety devices and thermometry calibration. In short: legacy leaded fusible alloy; melts near 98–110 °C; superseded by lead-free grades.
What is the yield strength of Bi50Pb25Sn25?
Bi50Pb25Sn25 has a typical yield strength of 18 MPa (2.61 ksi) and a tensile strength of 30 MPa (4.35 ksi) — weaker than 77% of solder & low-melting alloy grades.
Is Bi50Pb25Sn25 easy to machine?
Not especially — machinability is rated fair (40/100, better than 65% of solder & low-melting alloy grades). Machines only with very sharp high-rake tools, light cuts and flood coolant — the alloy smears and creeps; freeze-chucking or wax support is common.
Can Bi50Pb25Sn25 be welded?
Not readily — weldability is rated not recommended (10/100). Not weldable in any conventional sense; parts are joined by remelting the alloy itself or by soldering with the same composition (rosin flux, 130–160 °C bath).
What surface finishes work on Bi50Pb25Sn25?
Cannot be anodized or hard-plated; leave as-cast or lightly scrape/burnish. Surfaces dull in humid air; lead content requires handling and disposal controls and rules out RoHS/food-contact use.
Can Bi50Pb25Sn25 be formed, bent or molded?
Ideal for gravity/dip casting into silicone, plaster or steel moulds at 130–160 °C; very low shrinkage reproduces fine detail, but overheating above ~250 °C causes dross and dezincification of brass tooling.
What is the maximum service temperature of Bi50Pb25Sn25?
Bi50Pb25Sn25 is rated for continuous use to about 50°C (122 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Bi50Pb25Sn25 cost?
Bi50Pb25Sn25 is a high-cost solder & low-melting 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
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys (Low-Melting/Fusible Alloys) — ASM International (1990)
- Smithells Metals Reference Book (Bi-Pb-Sn ternary system) — Butterworth-Heinemann (2004)
- Fusible alloy property tables (Bi-Pb-Sn 98 °C class) — specialty low-melting-alloy producers (2022)
- ASTM B774 — Standard Specification for Low Melting Point Alloys — ASTM (2016)
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.