# 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 extremely low coefficient of thermal expansion. This unique property makes it an ideal material for applications requiring dimensional stability across a wide temperature range.

## Composition and Properties

The chemical composition of Alloy 36 typically consists of:

– Nickel: 36%
– Iron: Balance
– Small amounts of carbon, manganese, silicon, and sulfur

Key properties include:

– Low coefficient of thermal expansion (approximately 1.2 × 10-6/°C between 20-100°C)
– Good thermal conductivity
– Excellent dimensional stability
– Good machinability and weldability

## Applications of Alloy 36

Due to its unique characteristics, Alloy 36 finds use in various precision applications:

### 1. Aerospace Industry

Used in aircraft instruments, satellite components, and other aerospace applications where dimensional stability is critical.

### 2. Electronics

Essential for precision electronic components, including lead frames and semiconductor manufacturing equipment.

### 3. Scientific Instruments

Widely employed in telescopes, laser systems, and other optical instruments requiring minimal thermal expansion.

### 4. Cryogenic Applications

Performs well in extremely low-temperature environments, making it suitable for cryogenic equipment.

## Advantages Over Other Materials

Alloy 36 offers several advantages compared to other low-expansion materials:

– More cost-effective than many alternatives
– Better machinability than ceramics
– Superior dimensional stability compared to standard steels
– Excellent corrosion resistance in many environments

## Fabrication and Processing

The alloy can be readily fabricated using standard techniques:

– Machining: Can be machined using conventional methods
– Welding: Suitable for most welding processes
– Heat treatment: Typically used in the annealed condition

## Conclusion

Alloy 36 (UNS K93600) remains a critical material for precision engineering applications where thermal expansion must be minimized. Its unique combination of properties ensures continued demand across multiple high-tech industries. As technology advances and the need for precision grows, Alloy 36 will likely maintain its position as a material of choice for critical applications requiring exceptional dimensional stability.