Alloy 90 UNS N07090: Properties and Applications

July 13, 2025 / By

# Alloy 90 UNS N07090: Properties and Applications

## Introduction to Alloy 90 UNS N07090

Alloy 90, also known as UNS N07090, is a nickel-chromium-cobalt alloy that offers exceptional high-temperature strength and corrosion resistance. This superalloy is widely used in demanding applications where materials must withstand extreme conditions while maintaining structural integrity.

## Chemical Composition

The unique properties of Alloy 90 stem from its carefully balanced chemical composition:

– Nickel (Ni): 55-60%
– Chromium (Cr): 18-21%
– Cobalt (Co): 15-21%
– Molybdenum (Mo): 3-5%
– Titanium (Ti): 2.5-3.5%
– Aluminum (Al): 1.0-2.0%
– Iron (Fe): ≤2.0%
– Carbon (C): ≤0.12%
– Manganese (Mn): ≤1.0%
– Silicon (Si): ≤1.0%

## Mechanical Properties

Alloy 90 exhibits impressive mechanical characteristics that make it suitable for high-stress applications:

– Tensile Strength: 1200-1400 MPa (at room temperature)
– Yield Strength: 800-1000 MPa (at room temperature)
– Elongation: 10-20%
– Hardness: 30-40 HRC
– Creep Resistance: Excellent at temperatures up to 980°C (1800°F)

## Physical Properties

The physical characteristics of Alloy 90 include:

– Density: 8.19 g/cm³
– Melting Range: 1290-1350°C (2350-2460°F)
– Thermal Expansion Coefficient: 12.6 μm/m·°C (20-1000°C)
– Thermal Conductivity: 11.2 W/m·K (at 100°C)
– Electrical Resistivity: 1.25 μΩ·m (at 20°C)

## Key Advantages

Alloy 90 offers several distinct advantages over other high-temperature alloys:

– Exceptional high-temperature strength and stability
– Outstanding oxidation resistance up to 1100°C (2010°F)
– Good resistance to thermal fatigue
– Excellent creep-rupture properties
– Maintains mechanical properties at elevated temperatures
– Good fabricability and weldability

## Common Applications

Due to its remarkable properties, Alloy 90 finds use in numerous demanding applications:

### Aerospace Industry

– Turbine blades and vanes
– Combustion chambers
– Afterburner components
– Rocket engine parts

### Power Generation

– Gas turbine components
– Steam turbine blades
– High-temperature fasteners
– Heat exchangers

### Industrial Applications

– Furnace components
– Heat treating equipment
– Chemical processing equipment
– Nuclear reactor components

## Fabrication and Processing

Alloy 90 can be processed using standard techniques, though some considerations are necessary:

### Machining

– Requires rigid machine setups
– Use positive rake tools with carbide or ceramic inserts
– Maintain adequate coolant flow
– Lower cutting speeds than for steel

### Welding

– Gas tungsten arc welding (GTAW) is preferred
– Use matching filler metal
– Preheating to 200-300°C (400-600°F) recommended
– Post-weld heat treatment often required

### Heat Treatment

– Solution annealing at 1080-1120°C (1975-2050°F)
– Aging at 700-800°C (1290-1470°F)
– Stress relieving at 870-900°C (1600-1650°F)

## Comparison with Similar Alloys

Alloy 90 offers distinct advantages compared to other high-temperature alloys:

– Higher creep strength than Inconel 718 at temperatures above