Solder & Low-Melting Alloy Pb80Sn20: Properties

What is Pb80Sn20?

Pb80Sn20 is a high-lead, low-tin soft solder (ASTM B32 Sn20, HLSnPb20-80) whose 183–277 °C pasty range gives a long plastic working window. It is specified where working time matters more than joint strength — dent and seam filling on steel bodywork and low-cost general soldering — and is supplied as bar, ingot, solid and cored wire, paste and preforms. Mechanical values are low at 27 MPa tensile, 14 MPa yield, 40 % elongation and 11 HB, so it carries no structural load and creeps under sustained stress. Lead content rules it out of RoHS electronics; Pb70Sn30 wets better and is stronger where a shorter pasty range is acceptable. Pb80Sn20 has a density of 10.2 g/cm³ (0.368 lb/in³), heavier than 81% of solder & low-melting alloy grades. It melts at 183°C (361 °F). Pb80Sn20 has a yield strength of 14 MPa (2.03 ksi) and a tensile strength of 27 MPa (3.92 ksi) — weaker than 85% of solder & low-melting alloy grades. Elongation at break is 40% and the elastic modulus is 23 GPa (3.34 Msi).

What is Pb80Sn20 used for?

auto body solder
seam filling
low-cost general soldering

Advantages

Low embodied carbon — 4.5 kg CO₂/kg, better than 78% of solder & low-melting alloy grades

Limitations

Low strength — 14 MPa (2.03 ksi), worse than 85% of solder & low-melting alloy grades
Heavy — 10.2 g/cm³ (0.368 lb/in³), worse than 81% of solder & low-melting alloy grades
Low stiffness — 23 GPa (3.34 Msi), worse than 75% of solder & low-melting alloy grades

Pb80Sn20 properties

Typical room-temperature values; bars are the position among solder & low-melting alloy grades.

Physical3

Pb80Sn20 has a density of 10.2 g/cm³ (0.368 lb/in³), heavier than 81% of solder & low-melting alloy grades. It melts at 183°C (361 °F).

Density10.2 g/cm³0.37 lb/in³

Melting Point (Solidus)183°C361 °F

Liquidus Temperature277°C531 °F

Mechanical9

Pb80Sn20 has a yield strength of 14 MPa (2.03 ksi) and a tensile strength of 27 MPa (3.92 ksi) — weaker than 85% of solder & low-melting alloy grades. Elongation at break is 40% and the elastic modulus is 23 GPa (3.34 Msi).

Elastic (Young's) Modulus23 GPa3.3 Msi

Shear Modulus8.2 GPa1.2 Msi

Bulk Modulus46 GPa6.7 Msi

Poisson's Ratio0.42

Tensile Strength (Ultimate)27 MPa3.9 ksi

Yield Strength (0.2% offset)14 MPa2 ksi

Elongation at Break40%

Shear Strength21 MPa3 ksi

Hardness, Brinell11 HB

Thermal6

Pb80Sn20 is rated for continuous service to 100°C (212 °F). It conducts heat at 40 W/m·K (23.1 BTU/hr·ft·°F), worse than 58% of solder & low-melting alloy grades. Thermal expansion is 26.5 µm/m·K (14.7 µin/in·°F).

Thermal Conductivity40 W/m·K23.1 BTU/hr·ft·°F

Specific Heat Capacity150 J/kg·K0.04 BTU/lb·°F

Thermal Expansion (CTE, 20–100 °C)26.5 µm/m·K14.7 µin/in·°F

Latent Heat of Fusion30 J/g12.9 BTU/lb

Max Service Temperature (continuous)100°C212 °F

Min Service Temperature-60°C-76 °F

Electrical3

Pb80Sn20 conducts electricity at 8.7 % IACS, worse than 59% of solder & low-melting alloy grades.

Electrical Conductivity8.7 % IACS

Electrical Resistivity1.98×10⁻⁷ Ω·m7.8 µΩ·in

Magnetic Responsenon-magnetic

Chemical & Environmental3

Corrosion resistance is fair (40/100), worse than 82% of solder & low-melting alloy grades.

Galvanic Potential (seawater, vs SCE)-0.5 V

Corrosion ResistanceFair40/100

Chemical Resistance SummaryResists neutral water, atmosphere and sulfuric acid (protective sulfate film); attacked by acetic and other organic acids, nitric acid and strong alkalis; corrodes rapidly under active/acid flux residues if not cleaned.

Sustainability4

Producing a kilogram of Pb80Sn20 takes about 64 MJ of energy and emits 4.5 kg of CO₂ — less than 77% of solder & low-melting alloy grades. Typical recycled content is 60%.

Embodied Energy (primary production)64 MJ/kg27,515 BTU/lb

Embodied Carbon (primary production)4.5 kg CO₂/kg

Embodied Water200 L/kg24 gal/lb

Typical Recycled Content60%

Manufacturability7

Pb80Sn20's machinability is fair (35/100, better than 58% of solder & low-melting alloy grades); weldability poor (20/100); formability excellent (85/100).

MachinabilityFair35/100

WeldabilityPoor20/100

Formability (cold)Excellent85/100

CastabilityVery good80/100

Brazeability / SolderabilityExcellent90/100

PolishabilityFair40/100

Anodizing Responsen/a — not an anodizable alloy; surfaces are painted, tinned or left as filed

Common Calculations5

Specific Strength (UTS / density)calculated3 kN·m/kg

Specific Stiffness (E / density)calculated2.3 MN·m/kg

Modulus of Resiliencecalculated4 kJ/m³

Thermal Diffusivitycalculated26.1 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 solder & low-melting alloy family

Yield strength against density for every solder & low-melting alloy grade FabDigit runs. Pb80Sn20 is highlighted; hover a dot for its name, or open the interactive family chart.

Working with Pb80Sn20

Is Pb80Sn20 easy to machine?

Extremely soft and gummy — use sharp, high-rake tools, generous clearance and no coolant creep; in practice it is shaped by body files, vixen files and sanding rather than cut.

Can Pb80Sn20 be welded?

Not fusion welded; joints are made by re-melting with torch or iron, using an acid (zinc chloride) flux on steel and tinning the base metal first.

Can Pb80Sn20 be formed, bent or molded?

The long 183–277 °C pasty range lets it be paddled, wiped and modelled with wooden or steel paddles; keep the workpiece in the plastic range and avoid overheating past liquidus, which makes it run.

Pb80Sn20 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
SnASTM B32 grade Sn20	19.5 – 20.5	20
Sb0.20 max for low-antimony variants	≤ 0.5	0.1
Bi	≤ 0.25
Cu	≤ 0.08
Ag	≤ 0.02
Fe	≤ 0.02
As	≤ 0.03
Zn	≤ 0.01
Al	≤ 0.01
Pbbalance, nominally 80 %	balance

What surface finishes work on Pb80Sn20?

File and sand flush, then wash off all acid flux residue with alkaline neutralizer before priming — trapped chloride flux will blister paint and corrode the steel substrate.

Equivalent designations

Standards and trade names that resolve to Solder & Low-Melting Alloy Pb80Sn20 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.

ASTM: B32 Sn20
ISO: 9453-117
GB (China): HLSnPb20-80

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How much does Pb80Sn20 cost?

Pb80Sn20 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.

Pb80Sn20 — frequently asked

What is Pb80Sn20 used for?

Pb80Sn20 is typically used for auto body solder, seam filling and low-cost general soldering. In short: very long plastic range; cheapest wiping solder; filling, not structural joining.

What is the yield strength of Pb80Sn20?

Pb80Sn20 has a typical yield strength of 14 MPa (2.03 ksi) and a tensile strength of 27 MPa (3.92 ksi) — weaker than 85% of solder & low-melting alloy grades.

Is Pb80Sn20 easy to machine?

Not especially — machinability is rated fair (35/100, better than 58% of solder & low-melting alloy grades). Extremely soft and gummy — use sharp, high-rake tools, generous clearance and no coolant creep; in practice it is shaped by body files, vixen files and sanding rather than cut.

Can Pb80Sn20 be welded?

Not readily — weldability is rated poor (20/100). Not fusion welded; joints are made by re-melting with torch or iron, using an acid (zinc chloride) flux on steel and tinning the base metal first.