# Alloy 925 UNS N09925: Properties and Applications
## Introduction to Alloy 925 UNS N09925
Alloy 925, also known as UNS N09925, is a precipitation-hardened nickel-iron-chromium alloy with additions of molybdenum, copper, and titanium. This superalloy is renowned for its excellent combination of strength, corrosion resistance, and mechanical properties, making it suitable for demanding applications in various industries.
## Chemical Composition
The chemical composition of Alloy 925 plays a crucial role in its performance characteristics:
Keyword: Alloy 925 UNS N09925
– Nickel (Ni): 42-46%
– Iron (Fe): Balance
– Chromium (Cr): 19.5-22.5%
– Molybdenum (Mo): 2.5-3.5%
– Copper (Cu): 1.5-3.0%
– Titanium (Ti): 1.9-2.4%
– Aluminum (Al): 0.1-0.5%
– Carbon (C): ≤0.03%
## Mechanical Properties
Alloy 925 exhibits impressive mechanical properties, especially after precipitation hardening:
– Tensile Strength: 1100-1400 MPa (160-200 ksi)
– Yield Strength: 760-1100 MPa (110-160 ksi)
– Elongation: 15-25%
– Hardness: 30-40 HRC (after heat treatment)
## Physical Properties
The physical characteristics of Alloy 925 include:
– Density: 8.14 g/cm³ (0.294 lb/in³)
– Melting Point: 1350-1400°C (2460-2550°F)
– Thermal Expansion: 13.9 μm/m·°C (20-100°C)
– Electrical Resistivity: 0.98 μΩ·m
## Corrosion Resistance
Alloy 925 offers excellent corrosion resistance in various environments:
– Outstanding resistance to sour gas environments (H2S)
– Good resistance to chloride stress corrosion cracking
– Excellent performance in acidic environments
– Resistant to pitting and crevice corrosion
## Heat Treatment
The optimal properties of Alloy 925 are achieved through proper heat treatment:
– Solution Annealing: 980-1010°C (1800-1850°F) followed by rapid cooling
– Aging Treatment: 620-650°C (1150-1200°F) for 4 hours, air cooling
## Applications of Alloy 925
Due to its exceptional properties, Alloy 925 finds applications in various demanding industries:
### Oil and Gas Industry
– Downhole components
– Valve bodies and stems
– Wellhead equipment
– Tubing hangers
### Chemical Processing
– Pumps and valves
– Heat exchangers
– Reaction vessels
– Fasteners and springs
### Marine Applications
– Subsea equipment
– Propeller shafts
– Pump components
– Marine fasteners
## Advantages of Alloy 925
The key advantages that make Alloy 925 a preferred material choice include:
– High strength-to-weight ratio
– Excellent fatigue resistance
– Good weldability
– Maintains properties at elevated temperatures
– Resistance to sulfide stress cracking
## Conclusion
Alloy 925 UNS N09925 is a versatile nickel-iron-chromium superalloy that offers an exceptional combination of strength, corrosion resistance, and mechanical properties. Its unique characteristics make it particularly valuable in oil and gas, chemical processing, and marine applications where materials must withstand harsh environments while maintaining structural integrity. The alloy’s ability to be precipitation hardened allows for tailored mechanical properties to meet specific application requirements.
