Stellite6 UNS R30006 Alloy Properties and Applications

# Stellite6 UNS R30006 Alloy Properties and Applications

## Introduction to Stellite6 UNS R30006

Stellite6 (UNS R30006) is a cobalt-based superalloy known for its exceptional wear resistance, high-temperature strength, and excellent corrosion resistance. This alloy belongs to the Stellite family of materials developed by Deloro Stellite (now part of Kennametal) and has become a preferred choice for demanding industrial applications.

## Chemical Composition

The superior properties of Stellite6 stem from its carefully balanced chemical composition:

– Cobalt (Co): 58-65% (base metal)
– Chromium (Cr): 28-32%
– Tungsten (W): 4-6%
– Carbon (C): 1.0-1.4%
– Nickel (Ni): ≤3.0%

– Iron (Fe): ≤3.0%
– Silicon (Si): ≤2.0%
– Manganese (Mn): ≤1.0%

## Mechanical Properties

Stellite6 exhibits remarkable mechanical characteristics:

– Hardness: 38-45 HRC (as cast)
– Tensile Strength: 1000-1200 MPa
– Yield Strength: 700-900 MPa
– Elongation: 1-3%
– Density: 8.4 g/cm³

## Key Characteristics

Several properties make Stellite6 stand out among engineering materials:

### Wear Resistance

The alloy’s primary advantage is its outstanding resistance to various wear mechanisms, including:

– Abrasive wear
– Adhesive wear
– Galling
– Erosion

### Corrosion Resistance

Stellite6 performs well in corrosive environments:

– Excellent resistance to oxidizing acids
– Good performance in reducing acids
– Resistance to seawater corrosion
– Stability in high-temperature oxidizing atmospheres

### High-Temperature Performance

The alloy maintains its properties at elevated temperatures:

– Retains hardness up to 800°C (1472°F)
– Good creep resistance
– Oxidation resistance at high temperatures

## Manufacturing and Processing

Stellite6 can be produced and processed through various methods:

### Casting

– Investment casting
– Sand casting
– Centrifugal casting

### Powder Metallurgy

– Hot isostatic pressing (HIP)
– Metal injection molding (MIM)

### Surface Application

– Plasma transferred arc (PTA) welding
– Laser cladding
– Thermal spraying

## Applications of Stellite6 UNS R30006

The unique combination of properties makes Stellite6 suitable for numerous demanding applications:

### Industrial Components

– Valve seats and trim
– Pump components
– Bearing surfaces
– Wear plates

### Oil and Gas Industry

– Downhole tools
– Drill bits
– Valve components
– Wellhead equipment

### Aerospace Applications

– Turbine blades
– Combustion chamber components
– Exhaust valves

### Medical Devices

– Surgical instruments
– Dental tools
– Orthopedic implants

### Power Generation

– Steam turbine components
– Nuclear reactor parts
– Boiler feed pump wear rings

## Comparison with Other Stellite Alloys

While Stellite6 offers excellent all-around performance, other Stellite grades may be preferable for specific applications:

– Stellite1: Higher hardness for extreme abrasion
– Stellite12: Better machinability
– Stellite21: Superior corrosion resistance
– Stellite190: Improved high-temperature strength

## Maintenance and Machining Considerations

Working with Stellite6 requires special attention:

### Machining

– Use carbide or ceramic tools
– Maintain rigid setups
– Employ slow speeds and heavy feeds
– Use ample coolant

### Grinding

– Silicon carbide or diamond wheels recommended
– Avoid excessive heat buildup
– Frequent dressing of wheels

### Welding

– Preheating to 400-500°C (752-932°F) often required
– Post-weld heat