Alloy 36 (UNS K93600) – Low Expansion Nickel-Iron Alloy for Precision Applications
# Alloy 36 (UNS K93600) – Low Expansion Nickel-Iron Alloy for Precision Applications
Introduction to Alloy 36
Alloy 36, also known by its UNS designation K93600, is a nickel-iron alloy renowned for its exceptionally low coefficient of thermal expansion (CTE) at temperatures up to 400°F (204°C). This unique property makes it an ideal material for applications requiring dimensional stability across varying temperature ranges.
Chemical Composition
The composition of Alloy 36 is carefully balanced to achieve its distinctive thermal properties:
- Nickel (Ni): 35-37%
- Iron (Fe): Balance
- Carbon (C): 0.05% max
- Manganese (Mn): 0.60% max
- Silicon (Si): 0.30% max
- Phosphorus (P): 0.025% max
- Sulfur (S): 0.025% max
Key Properties
Alloy 36 offers several remarkable characteristics that make it valuable for precision applications:
- Low coefficient of thermal expansion (approximately 1.2 × 10-6/°C from 20-100°C)
- Good mechanical properties at both room and elevated temperatures
- Excellent resistance to corrosion and oxidation
- High thermal conductivity
- Good machinability and weldability
Keyword: Alloy 36 UNS K93600
Applications
The unique properties of Alloy 36 make it indispensable in various industries:
1. Aerospace Industry
Used in aircraft instruments, gyroscopes, and other components requiring dimensional stability under temperature fluctuations.
2. Electronics
Essential for lead frames, semiconductor packages, and other electronic components where thermal expansion matching is critical.
3. Scientific Instruments
Employed in precision measuring devices, laser components, and optical systems where dimensional stability is paramount.
4. Energy Sector
Used in power generation equipment, particularly where thermal cycling occurs.
Comparison with Other Low Expansion Alloys
| Alloy | Composition | CTE (×10-6/°C) | Primary Applications |
|---|---|---|---|
| Alloy 36 | 36% Ni, bal. Fe | 1.2 | General precision applications |
| Invar 36 | 36% Ni, bal. Fe | 1.3 | Similar to Alloy 36 |
| Kovar | 29% Ni, 17% Co, bal. Fe | 5.3 | Glass-to-metal seals |
Fabrication and Processing
Alloy 36