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 (Ni): 34-37%
– Chromium (Cr): 17-20%
– Iron (Fe): Balance
– Silicon (Si): 0.75-1.50%
– Manganese (Mn): ≤2.00%
– Carbon (C): ≤0.08%
– Sulfur (S): ≤0.030%
– Phosphorus (P): ≤0.040%

## 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

Key physical properties of Alloy 330 include:

– Density: 8.08 g/cm³ (0.292 lb/in³)
– Melting Range: 1371-1427°C (2500-2600°F)
– Electrical Resistivity: 98.0 μΩ·cm
– Thermal Conductivity: 12.2 W/m·K (at 100°C)

## Corrosion Resistance

Alloy 330 demonstrates excellent resistance to:

– Oxidation at high temperatures
– Carburization
– Sulfidation
– Nitriding environments

## High-Temperature Performance

One of the most notable features of Alloy 330 is its ability to maintain strength and resist oxidation at elevated temperatures up to 1200°C (2200°F). The alloy forms a protective chromium oxide scale that prevents further oxidation.

## Fabrication and Welding

Alloy 330 can be readily fabricated using standard techniques:

– Hot working should be performed between 870-1230°C (1600-2250°F)
– Cold working requires intermediate annealing
– Welding can be performed using matching filler metals or nickel-based alloys

## Heat Treatment

The recommended heat treatment for Alloy 330 is:

– Annealing: 1038-1121°C (1900-2050°F) followed by rapid cooling
– Stress relieving: 899-927°C (1650-1700°F)

## Applications of Alloy 330

Alloy 330 finds applications in numerous industries, including:

### Heat Treating Industry

– Furnace muffles
– Retorts
– Trays and baskets
– Radiant tubes

### Petrochemical Industry

– Reformer tubes
– Catalyst support grids
– Pyrolysis equipment

### Power Generation

– Heat exchangers
– Superheater tubes
– Boiler components

### Other Applications

– Food processing equipment
– Chemical processing vessels
– Thermal oxidizers

## Advantages Over Other Alloys

Compared to other high-temperature alloys, Alloy 330 offers:

– Better thermal fatigue resistance than many austenitic stainless steels
– Superior carburization resistance compared to standard 300-series stainless steels
– More cost-effective than many nickel-based superalloys for certain applications

## Limitations

While Alloy 330 performs exceptionally well in many environments, it has some limitations:

– Not recommended for use in strongly reducing atmospheres
– Limited resistance to halogen acids
– Not suitable for marine environments with chloride exposure

## Conclusion

Alloy 330 UNS N08330 remains a versatile and reliable material for high-temperature applications where oxidation and carburization