# Alloy K-500 UNS N05500: Properties and Applications
## Introduction to Alloy K-500
Alloy K-500, also known as UNS N05500, is a precipitation-hardenable nickel-copper alloy that offers a combination of high strength and excellent corrosion resistance. This alloy is derived from the popular Alloy 400 (UNS N04400) but with the addition of aluminum and titanium, which allow it to be strengthened through heat treatment.
## Chemical Composition
The chemical composition of Alloy K-500 plays a crucial role in its properties:
– Nickel (Ni): 63.0% minimum
– Copper (Cu): 27.0-33.0%
– Aluminum (Al): 2.3-3.15%
– Titanium (Ti): 0.35-0.85%
– Iron (Fe): 2.0% maximum
– Manganese (Mn): 1.5% maximum
– Carbon (C): 0.25% maximum
– Silicon (Si): 0.5% maximum
– Sulfur (S): 0.01% maximum
## Mechanical Properties
Alloy K-500 exhibits impressive mechanical properties, especially in the aged condition:
– Tensile Strength: 1100-1300 MPa (160-190 ksi)
– Yield Strength: 690-1030 MPa (100-150 ksi)
– Elongation: 20-30%
– Hardness: 25-35 HRC
– Modulus of Elasticity: 179 GPa (26 x 10^6 psi)
## Physical Properties
The physical characteristics of Alloy K-500 include:
Keyword: Alloy K-500 UNS N05500
– 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: 21.9 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 maintains excellent corrosion resistance similar to Alloy 400, with additional benefits:
– Outstanding resistance to seawater and marine atmospheres
– Good resistance to sulfuric, hydrochloric, and hydrofluoric acids
– Excellent resistance to stress corrosion cracking
– Superior performance in brackish and chlorinated waters
– Resistance to biofouling and microbiologically influenced 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 or furnace cooling depending on desired properties
## Applications of Alloy K-500
Due to its unique combination of properties, Alloy K-500 finds use in various demanding applications:
### Marine Engineering
– Pump shafts and impellers
– Valve components
– Fasteners and bolts
– Marine propeller shafts
– Offshore drilling components
### Oil and Gas Industry
– Downhole equipment
– Wellhead components
– Valve stems and trim
– Pump shafts in sour gas service
### Aerospace and Defense
– Aircraft fuel and hydraulic systems
– Missile components
– High-strength fasteners
– Bearings and bushings
### Chemical Processing
– Mixer shafts and agitators
– Heat exchanger tubing
– Process vessels in corrosive environments
– Pumps and valves for chemical handling
## Fabrication and Welding
Alloy K-500 can be fabricated using standard techniques with some considerations:
– Hot working should be performed between 871-1149°C (1600-