Alloy 330 UNS N08330: Properties and Applications

# Alloy 330 UNS N08330: Properties and Applications

## Introduction to Alloy 330 UNS N08330

Alloy 330, also known as UNS N08330, is a nickel-iron-chromium austenitic alloy designed for high-temperature applications. This material offers excellent resistance to oxidation and carburization, making it a popular choice in various industrial sectors.

## Chemical Composition

The chemical composition of Alloy 330 plays a crucial role in its performance characteristics:

– Nickel: 34-37%
– Chromium: 17-20%
– Iron: Balance
– Carbon: 0.08% max

– Manganese: 2.0% max
– Silicon: 1.5% max
– Sulfur: 0.03% max
– Phosphorus: 0.045% max

## Mechanical Properties

Alloy 330 exhibits impressive mechanical properties across a wide temperature range:

– Tensile Strength: 75 ksi (517 MPa) min
– Yield Strength: 30 ksi (207 MPa) min
– Elongation: 30% min
– Hardness: Rb 85 max

## Physical Properties

The physical characteristics of Alloy 330 include:

– Density: 0.286 lb/in³ (7.92 g/cm³)
– Melting Point: 2500-2600°F (1371-1427°C)
– Thermal Expansion Coefficient: 8.9 µin/in-°F (20-1000°C)
– Electrical Resistivity: 780 ohm-cir mil/ft
– Modulus of Elasticity: 28 x 10⁶ psi (193 GPa)

## Key Features and Advantages

Alloy 330 offers several notable benefits:

– Excellent resistance to oxidation and carburization
– Good mechanical strength at elevated temperatures
– Superior resistance to thermal cycling
– Good fabricability and weldability
– Resistance to sulfur-containing atmospheres

## Common Applications

Due to its unique properties, Alloy 330 finds use in numerous demanding applications:

### Industrial Furnace Components

– Radiant tubes
– Muffles
– Retorts
– Furnace baskets

### Heat Treatment Equipment

– Annealing covers
– Carburizing fixtures
– Quenching fixtures

### Petrochemical Industry

– Reformer tubes
– Catalyst support grids
– Heat exchanger tubing

### Power Generation

– Combustion chambers
– Heat recovery systems
– Boiler components

## Fabrication and Welding Considerations

Alloy 330 can be readily fabricated using standard techniques:

– Machining: Requires slower speeds and heavier feeds than carbon steel
– Forming: Can be cold worked but may require annealing for severe forming
– Welding: Recommended methods include GTAW and GMAW with matching filler metal

## Heat Treatment

The standard heat treatment for Alloy 330 involves:

– Annealing at 1800-2100°F (982-1149°C)
– Rapid cooling to room temperature
– Stress relieving at 1200-1400°F (649-760°C) when required

## Corrosion Resistance

Alloy 330 demonstrates excellent resistance to:

– Oxidation up to 2100°F (1149°C)
– Carburizing environments
– Sulfidizing conditions
– Nitriding atmospheres

## Comparison with Similar Alloys

Compared to other high-temperature alloys:

– Better oxidation resistance than 304 and 309 stainless steels
– Superior carburization resistance compared to Alloy 800
– More cost-effective than some nickel-based superalloys

## Conclusion

Alloy 330 UNS N08330 remains a versatile material for high-temperature applications where oxidation resistance and mechanical strength are critical. Its balanced composition and reliable performance make it a preferred choice across multiple industries dealing with extreme thermal conditions.