Hastelloy N
About Hastelloy N
Name and Equivalent Name: Hastelloy N, identified as UNS N10003, conforms to ASTM standards B619 and B622 and is known by the Chinese standard GB/T 14992: NS321. Commonly referred to as Alloy N, it offers exceptional performance under thermal stress and corrosive conditions.
Hastelloy N Basic Introduction
Hastelloy N is a nickel-based superalloy designed for high-temperature service, particularly in nuclear reactors. It maintains exceptional thermal fatigue and corrosion resistance, making it suitable for environments with significant thermal cycling and chemical exposure.
The alloy is optimized for long service life at temperatures up to 600°C, with excellent mechanical strength and stability in cyclic environments. Hastelloy N is frequently used in molten salt reactors and aerospace applications requiring extreme heat resistance.
Alternative Superalloys of Hastelloy N
Alternative superalloys include Hastelloy C-276, which offers superior corrosion resistance but is better suited for chemical environments. Inconel 625 provides excellent high-temperature strength but lacks the specific corrosion resistance for molten salts. Alloy 600 is another option, excelling in heat and corrosion resistance but with slightly different mechanical properties. Monel 400 can be used in marine applications but has lower thermal fatigue resistance.
Hastelloy N Design Intention
Hastelloy N was designed to meet the demands of high-temperature applications, particularly in nuclear reactors and molten salt systems. Its composition minimizes the risk of cracking due to thermal fatigue and ensures structural integrity under cyclic conditions.
The alloy was also intended to resist corrosion from highly reactive chemicals and salts, allowing for extended service life with minimal degradation. This makes it suitable for critical components requiring high reliability in harsh environments.
Hastelloy N Chemical Composition
The chemical composition of Hastelloy N is tailored to provide superior resistance to corrosion and mechanical stress.
Element | Content (wt%) |
|---|---|
Nickel (Ni) | 71.0 min |
Chromium (Cr) | 6.0 - 10.0 |
Molybdenum (Mo) | 15.0 - 18.0 |
Iron (Fe) | 5.0 - 6.0 |
Carbon (C) | Max 0.02 |
Cobalt (Co) | Max 0.5 |
Hastelloy N Physical Properties
Hastelloy N exhibits physical solid properties, ensuring performance in extreme conditions.
Property | Value |
|---|---|
Density (g/cm³) | 9.19 |
Melting Point (°C) | 1427 |
Thermal Conductivity (W/(m·K)) | 11.9 |
Modulus of Elasticity (GPa) | 207 |
Metallographic Structure of Hastelloy N Superalloy
Hastelloy N has a face-centered cubic (FCC) structure, providing high ductility and stability under thermal stress. This microstructure enables the alloy to maintain mechanical strength at high temperatures, preventing deformation in cyclic environments.
The low carbon content of Hastelloy N ensures minimal carbide formation, reducing the risk of intergranular corrosion. This stability is essential for welding applications and high-temperature exposure, ensuring the alloy’s long-term reliability in critical systems.
Hastelloy N Mechanical Properties
Hastelloy N offers robust mechanical properties, making it ideal for demanding environments.
Mechanical Property | Value |
|---|---|
Tensile Strength (MPa) | 760 - 800 |
Yield Strength (MPa) | 320 - 450 |
Creep Strength | Effective at 600°C |
Fracture Toughness | Good |
Fatigue Strength | Strong for cyclic environments |
Thermal Fatigue Resistance | High |
Creep Rupture Life | Long service at 600°C |
Hardness (HRC) | Rockwell C25 - 35 |
Elongation (%) | ~45 |
Elastic Modulus (GPa) | ~210 |
Key Features of Hastelloy N Superalloy
1. High-Temperature Stability
Hastelloy N maintains mechanical strength and structural integrity at temperatures up to 600°C, making it suitable for molten salt reactors and other high-heat applications.
2. Exceptional Corrosion Resistance
The alloy provides superior resistance to corrosion from reactive chemicals, including molten salts and high-temperature gases, ensuring long service life in extreme environments.
3. Resistance to Thermal Fatigue
Hastelloy N performs exceptionally well under cyclic thermal stress, reducing the risk of cracking and failure in components exposed to fluctuating temperatures.
4. Weldability and Fabrication
With low carbon content, Hastelloy N minimizes carbide precipitation during welding, allowing for easy fabrication without compromising corrosion resistance or mechanical properties.
5. Long Service Life
The alloy’s stress, fatigue, and chemical corrosion resistance ensures long-lasting performance in critical systems with minimal maintenance.
Hastelloy N Superalloy’s Machinability
Vacuum Investment Casting: Hastelloy N is not ideal for Vacuum Investment Casting due to its composition, which limits precise dimensional control and surface finish needed for intricate castings.
Single Crystal Casting: Hastelloy N cannot be used for Single Crystal Casting as it is not formulated to develop single-crystal structures essential for turbine blades and aerospace components.
Equiaxed Crystal Casting: Hastelloy N is compatible with Equiaxed Crystal Casting, as its alloy composition supports the formation of randomly oriented grains suitable for structural applications.
Directional Casting: Hastelloy N can be employed in Superalloy Directional Casting because it offers the desired strength for high-stress environments like reactors and heat exchangers.
Powder Metallurgy Turbine Disc: Hastelloy N is generally not used for Powder Metallurgy Turbine Discs due to its tendency to form grain boundaries under extreme conditions, reducing efficiency.
Precision Forging: The alloy performs well in Superalloy Precision Forging, ensuring good mechanical strength and fatigue resistance in cyclic thermal environments.
Superalloy 3D Printing: Hastelloy N is not widely adopted in Superalloy 3D Printing due to challenges with printing complex geometries and maintaining its corrosion-resistant properties.
Superalloy CNC Machining: The alloy is compatible with CNC Machining techniques, provided proper cooling and tooling are used to mitigate machining difficulty caused by high hardness.
Superalloy Welding: Hastelloy N is suitable for Superalloy Welding due to its low carbon content, minimizing carbide precipitation and preserving corrosion resistance.
Hot Isostatic Pressing (HIP): The alloy benefits from Hot Isostatic Pressing (HIP), which improves density and reduces porosity for enhanced mechanical properties.
Hastelloy N Superalloy Applications
Aerospace and Aviation: Hastelloy N is used in Aerospace and Aviation for components like heat exchangers and exhaust systems, thanks to its high-temperature resistance.
Power Generation: In Power Generation, the alloy serves in turbines and reactors, enduring cyclic thermal stress effectively.
Oil and Gas: Hastelloy N is ideal for Oil and Gas pipelines and valves exposed to corrosive and high-temperature environments.
Energy: The alloy finds application in Energy systems such as molten salt reactors, ensuring long-term performance at elevated temperatures.
Marine: In marine environments, Hastelloy N resists corrosion and serves in desalination plants and offshore structures.
Mining: Mining operations utilize Hastelloy N in harsh chemical environments, ensuring durability in pumps and mixers.
Automotive: Hastelloy N is employed in Automotive exhaust systems where high-temperature stability and corrosion resistance are essential.
Chemical Processing: In Chemical Processing, the alloy handles reactive chemicals without compromising integrity, offering superior corrosion resistance.
Pharmaceutical and Food: The alloy ensures hygiene and chemical stability in Pharmaceutical and Food applications, particularly in mixers and storage tanks.
Military and Defense: Hastelloy N supports critical military and defense systems that can withstand extreme conditions in military aircraft and reactors.
Nuclear: Nuclear reactors benefit from Hastelloy N’s high-temperature resistance and ability to handle radiation exposure.
When to Choose Hastelloy N Superalloy
Hastelloy N is the go-to material for thermal stability and corrosion resistance applications. Ideal for high-temperature reactors, aerospace heat exchangers, and chemical processing, the alloy offers reliable performance in environments with fluctuating temperatures and aggressive chemicals. For custom superalloy parts, Hastelloy N ensures structural integrity and long service life.
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