Alloy K-500 UNS N05500: Properties and Applications

# Alloy K-500 UNS N05500: Properties and Applications

## Introduction to Alloy K-500

Alloy K-500, also known as UNS N05500, is a nickel-copper alloy that combines the excellent corrosion resistance of Monel 400 with the added benefits of precipitation hardening. This unique combination makes it suitable for a wide range of demanding applications in various industries.

## Chemical Composition

The chemical composition of Alloy K-500 includes:

– Nickel: 63% minimum
– Copper: 27-33%
– Aluminum: 2.3-3.15%
– Titanium: 0.35-0.85%
– Iron: 2.0% maximum
– Manganese: 1.5% maximum
– Carbon: 0.25% maximum
– Silicon: 0.5% maximum
– Sulfur: 0.01% maximum

## Mechanical Properties

Alloy K-500 offers impressive mechanical properties:

– Tensile strength: 1100-1500 MPa (160-220 ksi)
– Yield strength: 690-1100 MPa (100-160 ksi)
– Elongation: 20-35%
– Hardness: 25-35 HRC
– Modulus of elasticity: 179 GPa (26 x 10^6 psi)

## Physical Properties

Key physical properties of Alloy K-500 include:

– Density: 8.44 g/cm³ (0.305 lb/in³)
– Melting range: 1315-1350°C (2400-2460°F)
– Electrical resistivity: 51.0 μΩ·cm
– Thermal conductivity: 21.8 W/m·K (151 BTU·in/hr·ft²·°F)
– Coefficient of thermal expansion: 13.9 μm/m·°C (20-100°C)

## Corrosion Resistance

Alloy K-500 exhibits excellent corrosion resistance similar to Monel 400, with additional benefits:

– Outstanding resistance to seawater and saltwater corrosion
– Good resistance to sulfuric and hydrofluoric acids
– Excellent performance in alkaline environments
– Resistance to stress corrosion cracking
– Superior resistance to pitting and crevice corrosion

## Heat Treatment

The precipitation hardening process for Alloy K-500 typically involves:

1. Solution annealing at 982°C (1800°F) followed by rapid cooling
2. Aging at 593-621°C (1100-1150°F) for 4-16 hours
3. Air cooling to room temperature

## Applications of Alloy K-500

Alloy K-500 finds applications in various industries:

### Marine Engineering

– Pump shafts and impellers
– Marine propeller shafts
– Fasteners and bolts for offshore platforms
– Valve components in seawater systems

### Oil and Gas Industry

– Downhole tools and equipment
– Wellhead components
– Valve stems and trim
– Instrumentation components

### Aerospace Industry

– Aircraft fuel pump components
– Turbine blades and discs
– Rocket motor cases
– Fasteners and fittings

### Chemical Processing

– Mixer shafts and agitators
– Heat exchanger tubes
– Reactor vessels
– Process piping systems

## Fabrication and Machining

Alloy K-500 can be fabricated using standard techniques:

– Machining: Similar to austenitic stainless steels but requires rigid setups
– Welding: Can be welded using GTAW, GMAW, and SMAW processes
– Forming: Can be cold worked but requires more force than Monel 400
– Heat treatment: Requires precise control for optimal properties

## Advantages of Alloy K-500

The key advantages of Alloy K-500 include:

– High strength combined with excellent corrosion resistance
– Good fatigue resistance
– Non-magnetic properties
– Maintains