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Solder & Low-Melting Alloy Sn60Pb40E vs Sn91Zn9

Solder & Low-Melting Alloy · grade comparison

Solder & Low-Melting Alloy Sn60Pb40E and Sn91Zn9 are both solder & low-melting alloy grades. Sn91Zn9 is the stronger of the two: yield strength 38 MPa (5.51 ksi) against 30 MPa (4.35 ksi) for Sn60Pb40E, about 27% more; tensile strength follows at 65 MPa (9.43 ksi) vs 50 MPa (7.25 ksi). Sn91Zn9 is the more ductile: elongation 40% versus 35% for Sn60Pb40E, and Sn91Zn9 is harder (21 HB vs 16 HB). Sn91Zn9 is lighter (7.27 g/cm³ vs 8.5 g/cm³ for Sn60Pb40E) and Sn91Zn9 is stiffer (40 GPa vs 30 GPa). On the shop floor, Sn60Pb40E welds better (poor vs not recommended).

Sn60Pb40EChoose it when it will be welded.

Sn91Zn9Choose it when strength drives the design, or when the part is bent, formed or impact-loaded.

Sn60Pb40E vs Sn91Zn9: properties

Sn60Pb40ESn91Zn9

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

30 GPa4.4 Msi
40 GPa5.8 Msi

Shear Modulus

11 GPa1.6 Msi
15 GPa2.2 Msi

Bulk Modulus

48 GPa7 Msi
47 GPa6.8 Msi

Poisson's Ratio

0.4
0.36

Tensile Strength (Ultimate)

50 MPa7.3 ksi
65 MPa9.4 ksi

Yield Strength (0.2% offset)

30 MPa4.4 ksi
38 MPa5.5 ksi

Elongation at Break

35%
40%

Shear Strength

34 MPa4.9 ksi
40 MPa5.8 ksi

Fatigue Strength (Endurance Limit)

20 MPa2.9 ksi
—

Hardness, Brinell

16 HB
21 HB

Hardness, Vickers

14 HV
22 HV

Physical

Density and transition temperatures.

Density

8.5 g/cm³0.31 lb/in³
7.27 g/cm³0.26 lb/in³

Melting Point (Solidus)

183°C361 °F
199°C390 °F

Liquidus Temperature

190°C374 °F
199°C390 °F

Thermal

How each material carries heat and how hot it can run.

Thermal Conductivity

50 W/m·K28.9 BTU/hr·ft·°F
61 W/m·K35.2 BTU/hr·ft·°F

Specific Heat Capacity

180 J/kg·K0.04 BTU/lb·°F
230 J/kg·K0.05 BTU/lb·°F

Thermal Expansion (CTE, 20–100 °C)

24.5 µm/m·K13.6 µin/in·°F
24 µm/m·K13.3 µin/in·°F

Latent Heat of Fusion

42 J/g18.1 BTU/lb
65 J/g27.9 BTU/lb

Same in both: Max Service Temperature (continuous) 100°C212 °F · Min Service Temperature -55°C-67 °F

Electrical

Conductivity and insulation.

Electrical Conductivity

11.5 % IACS
12.5 % IACS

Electrical Resistivity

1.5×10⁻⁷ Ω·m5.91 µΩ·in
1.38×10⁻⁷ Ω·m5.43 µΩ·in

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Galvanic Potential (seawater, vs SCE)

-0.5 V
-0.75 V

Corrosion Resistance

40 / 100
25 / 100

Manufacturability

FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.

Weldability

20 / 100
10 / 100

Formability (cold)

90 / 100
85 / 100

Castability

92 / 100
85 / 100

Brazeability / Solderability

100 / 100
80 / 100

Polishability

20 / 100
—

Same in both: Machinability 30 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

200 MJ/kg85,985 BTU/lb
295 MJ/kg126,827 BTU/lb

Embodied Carbon (primary production)

10.5 kg CO₂/kg
16.5 kg CO₂/kg

Typical Recycled Content

15%
30%

Same in both: Embodied Water 300 L/kg35.9 gal/lb

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

6 kN·m/kg
9 kN·m/kg

Specific Stiffness (E / density)

3.5 MN·m/kg
5.5 MN·m/kg

Modulus of Resilience

15 kJ/m³
18 kJ/m³

Thermal Diffusivity

32.7 mm²/s
36.5 mm²/s

Thermal Shock Resistance Index

3
4

Strength versus weight

Yield strength against density for every solder & low-melting alloy grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.

125102050891011Density (g/cm³)Yield strength (MPa) — log scaleSn60Pb40ESn91Zn9

Manufacturing and finishing

CapabilitySn60Pb40ESn91Zn9
Default condition——
Relative cost$$$$ High$$$$ High
Min. machined wall——
Best machined surface——

Sn60Pb40E vs Sn91Zn9 — frequently asked

Is Sn91Zn9 stronger than Sn60Pb40E?

Yes. Sn91Zn9 has a typical yield strength of 38 MPa (5.51 ksi) against 30 MPa (4.35 ksi) for Sn60Pb40E — about 27% more. Tensile strength is 65 MPa (9.43 ksi) vs 50 MPa (7.25 ksi).

Which is cheaper, Sn60Pb40E or Sn91Zn9?

Both sit in the same relative cost tier ($$$$, high); the part price will be decided by machining time, tolerance and quantity rather than by the material.

Which welds better, Sn60Pb40E or Sn91Zn9?

Sn60Pb40E. Its weldability rates poor (20/100) against not recommended (10/100) for Sn91Zn9.

Ready to make it?

Upload a CAD file and FabDigit prices the part in Sn60Pb40E and Sn91Zn9 side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.

Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.