# N07090 Stainless Steel Alloy Properties and Applications

## Introduction to N07090 Stainless Steel

N07090 is a high-performance nickel-chromium alloy that falls under the category of superalloys. While not technically a stainless steel, it is often grouped with stainless alloys due to its excellent corrosion resistance and high-temperature performance. This alloy is known for its exceptional strength, oxidation resistance, and creep resistance at elevated temperatures.

## Chemical Composition of N07090

The N07090 alloy consists of:

– Nickel (Ni): 58-63%
– Chromium (Cr): 19-23%
– Cobalt (Co): 13-16%
– Molybdenum (Mo): 4-6%
– Titanium (Ti): 1.5-2.5%
– Aluminum (Al): 1.2-1.6%
– Iron (Fe): ≤1.0%
– Carbon (C): ≤0.08%
– Manganese (Mn): ≤0.50%

– Silicon (Si): ≤0.50%

## Mechanical Properties

N07090 exhibits impressive mechanical properties across a wide temperature range:

– Tensile Strength: 1200-1400 MPa (at room temperature)
– Yield Strength: 800-1000 MPa (at room temperature)
– Elongation: 15-25%
– Hardness: 30-40 HRC
– Creep Strength: Excellent at temperatures up to 980°C (1800°F)

## Physical Properties

Key physical characteristics of N07090 include:

– Density: 8.22 g/cm³
– Melting Range: 1290-1345°C (2350-2450°F)
– Thermal Expansion Coefficient: 12.5 μm/m°C (20-1000°C)
– Thermal Conductivity: 11.4 W/m·K (at 100°C)
– Electrical Resistivity: 1.25 μΩ·m (at 20°C)

## Corrosion Resistance

N07090 offers outstanding corrosion resistance in various environments:

– Excellent oxidation resistance up to 1100°C (2000°F)
– Good resistance to carburizing and nitriding atmospheres
– Performs well in sulfur-containing environments
– Resistant to chloride-ion stress-corrosion cracking

## Heat Treatment

Proper heat treatment is crucial for optimizing N07090’s properties:

– Solution Annealing: 1080-1120°C (1975-2050°F) followed by rapid cooling
– Aging Treatment: 700-800°C (1290-1470°F) for 16 hours (typical)

## Fabrication and Machining

Working with N07090 requires special considerations:

– Hot Working: Performed at 1050-1200°C (1920-2190°F)
– Cold Working: Possible but requires intermediate annealing
– Machining: More difficult than standard stainless steels; requires rigid setups and positive rake tools
– Welding: Can be welded using matching filler metal; post-weld heat treatment recommended

## Applications of N07090 Alloy

N07090 finds use in demanding high-temperature applications:

– Gas turbine components (blades, vanes, combustors)
– Aerospace engine parts
– Industrial furnace components
– Nuclear reactor systems
– Chemical processing equipment
– Power generation systems
– Heat treatment fixtures

## Advantages Over Other Alloys

N07090 offers several benefits compared to similar alloys:

– Higher temperature capability than most stainless steels
– Better creep resistance than Inconel 718
– Superior oxidation resistance compared to cobalt-based alloys
– Excellent fatigue resistance under thermal cycling conditions

## Limitations and Considerations

While N07090 is an exceptional material, it has some limitations:

– Higher cost than standard stainless steels
– More difficult to machine and fabricate
– Requires specialized