Grade D Tin is a commercial-industrial refined tin with a minimum purity of 99.85% Sn. It is widely used where good tin content, easy processability, and cost efficiency are more important than ultra-high chemical purity.
This grade is typically selected for alloying, foundry work, and bulk industrial uses.
Basic Identification
| Property | Value |
|---|---|
| Purity | ≥ 99.85% Sn |
| Allotropic Form | β-Tin (White Tin) |
| Crystal Structure | Body-Centered Tetragonal (BCT) |
| Standards | ASTM B339, ISO 21948, EN 610 |
Typical Chemical Composition
| Element | Max Content (%) |
|---|---|
| Tin (Sn) | ≥ 99.85 |
| Lead (Pb) | ≤ 0.20 |
| Antimony (Sb) | ≤ 0.15 |
| Copper (Cu) | ≤ 0.10 |
| Iron (Fe) | ≤ 0.05 |
| Bismuth (Bi) | ≤ 0.05 |
| Arsenic (As) | ≤ 0.05 |
Mechanical Properties
| Property | Typical Value |
|---|---|
| Tensile Strength | 18 – 28 MPa |
| Yield Strength | Very low |
| Elongation | 25 – 35% |
| Hardness | ~8 – 12 HV |
| Ductility | Good |
| Creep Resistance | Moderate (for tin) |
Physical Properties
| Property | Value |
|---|---|
| Density | ~7.30 g/cm³ |
| Melting Point | ~231 – 232 °C |
| Electrical Conductivity | ~12 – 14% IACS |
| Thermal Conductivity | ~60 – 64 W/m·K |
| Magnetic Behavior | Diamagnetic |
| Appearance | Silvery-white to dull gray |
Strengthening & Metallurgical Behavior
Grade D tin is not heat treatable. Strength is achieved through solid-solution strengthening from lead, antimony, and copper, with minor work hardening.
This grade shows lower tin-whisker tendency than higher-purity tin and good dimensional stability in bulk industrial use.
Key Characteristics
✔ Economical and widely available
✔ Excellent castability and fluidity
✔ Good alloying behavior
✔ Reduced whisker risk
✔ Suitable for large-volume use
❌ Not food-grade or electronics-grade
Refining & Processing
Produced by smelting and fire refining with limited impurity control. No full electrolytic refining is applied, making it optimized for volume production and cost.
| Process | Performance |
|---|---|
| Melting | Excellent |
| Casting | Excellent |
| Rolling | Fair |
| Machining | Poor |
| Solderability | Fair |
Available Forms
Tin ingots / pigs
Tin bars
Granulated tin
Alloy feedstock
Recycled refined tin
Applications
🏭 Bronze alloys, Babbitt metals, pewter (industrial)
🏗 Float glass bath tin and industrial coatings
⚡ Low-grade solders and cable sheathing
Advantages
✔ Lower cost than Grade A, B, and C tin
✔ Excellent casting performance
✔ Ideal for alloying and foundry use
✔ Stable bulk supply
Limitations
❌ Not suitable for precision electronics
❌ Not food or pharma compliant
❌ Impurity-driven corrosion risk
❌ Limited electrical reliability
Grade Comparison
| Feature | Grade D | Grade C | Grade B |
|---|---|---|---|
| Purity | 99.85% | 99.90% | 99.95% |
| Cost | Lower | Medium | Higher |
| Electronics Use | No | Limited | Yes |
| Alloying Use | Excellent | Excellent | Excellent |
| Whisker Risk | Low | Lower | Low |
Why Choose Grade D Tin?
Grade D Tin (99.85%) is chosen for economy and metallurgical practicality. It delivers excellent processability, reduced whisker risk, and strong value for high-volume industrial and foundry applications where purity regulations are not critical.