Alloy 200,Nickel 200 Forgings,UNS N02200

Alloy 200,Nickel 200 Wire,UNS N02200

Introduction to Alloy 200 (Nickel 200 Wire, UNS N02200)

Alloy 200, commercially known as Nickel 200 and classified under UNS N02200, is a high-purity, commercially pure nickel alloy celebrated for its exceptional corrosion resistance, excellent thermal and electrical conductivity, and outstanding formability. As the foundational alloy of the pure nickel family, it features a minimum nickel content of 99.0 wt%, with controlled impurities to deliver reliable performance across a broad temperature range—from cryogenic conditions (-253°C/-423°F) up to 315°C/600°F. Unlike its low-carbon derivative (Nickel 201), Nickel 200 has a slightly higher carbon content (≤0.15 wt%), which provides moderate strength but requires caution in hydrogen-rich or high-temperature corrosive environments to avoid intergranular cracking. Its fully austenitic microstructure ensures exceptional ductility and toughness, even at near-absolute zero, making it a staple in industries where corrosion resilience, conductivity, and processability are critical. Nickel 200 wire, a key form of this alloy, is widely used in chemical processing, electronics, marine engineering, and aerospace—excelling in components like thermocouple sheaths, electrical connectors, chemical sensor wires, and low-temperature fasteners that demand consistent performance in mild to moderate aggressive environments.

1. Chemical Composition (Typical, wt%)

The chemical composition of UNS N02200 adheres to strict industry standards including ASTM B160 (for nickel and nickel-alloy rod, bar, and wire) and ASME SB160, with a focus on high nickel purity and controlled impurities to optimize corrosion resistance and conductivity. The typical composition is as follows:

Element

Content Range (wt%)

Function

Nickel (Ni)

99.0 min.

Serves as the primary matrix element, stabilizing the austenitic structure; eliminates brittle-to-ductile transition at cryogenic temperatures, ensuring exceptional toughness down to -253°C.

Carbon (C)

≤ 0.15

Provides moderate strength via limited solid-solution strengthening; requires controlled heating/cooling to avoid carbide (Ni₃C) precipitation in hydrogen-rich or corrosive environments.

Iron (Fe)

≤ 0.4

Minimized to avoid forming ferromagnetic phases (which degrade cryogenic performance) and prevent intergranular embrittlement; limited to improve hot workability during wire production.

Copper (Cu)

≤ 0.2

Trace element that slightly enhances corrosion resistance in mild acids without compromising thermal conductivity; controlled to avoid reducing ductility.

Manganese (Mn)

≤ 0.3

Aids in deoxidation during melting and improves cold workability for fine wire drawing; strictly controlled to avoid precipitating brittle intermetallic phases at low temperatures.

Silicon (Si)

≤ 0.1

Reduces oxide formation during hot processing; ultra-low content prevents oxide inclusions that act as stress concentrators in cryogenic or cyclic loading service.

Sulfur (S)

≤ 0.010

Strictly limited to avoid hot cracking during wire drawing and welding; reduces the risk of pitting corrosion in sulfur-containing environments (e.g., H₂S).

Phosphorus (P)

≤ 0.010

Controlled to avoid grain boundary embrittlement, a critical concern for components subjected to cyclic loading or cryogenic temperatures.

Cobalt (Co)

≤ 0.2

Trace element with minimal impact on properties; limited to maintain high nickel purity and preserve cryogenic ductility.

Oxygen (O)

≤ 0.015

Ultra-low content prevents forming oxide inclusions (e.g., NiO) that degrade fatigue life and reduce corrosion resistance.

2. Physical Properties

Nickel 200 wire exhibits exceptional physical properties, with thermal and electrical conductivity among the highest of industrial nickel alloys—making it ideal for heat transfer and electrical applications. Key properties (measured at specified temperatures) are:

Property

Value

Test Condition

Density

8.89 g/cm³

Room temperature (25°C)

Melting Point Range

1435 - 1455°C

-

Thermal Expansion Coefficient

13.5 × 10⁻⁶/°C

20 - 100°C; 4.3 × 10⁻⁶/°C (20 - -200°C)

Thermal Conductivity

90.9 W/(m·K)

25°C; 195 W/(m·K) (-200°C)

Electrical Resistivity

0.069 × 10⁻⁶ Ω·m

25°C; 0.015 × 10⁻⁶ Ω·m (-200°C)

Modulus of Elasticity

207 GPa

Room temperature (tensile); 230 GPa (-200°C)

Poisson’s Ratio

0.31

Room temperature; 0.33 (-200°C)

Curie Temperature

< -269°C

Remains non-ferromagnetic even at liquid helium temperatures (critical for magnetic and superconducting applications).

Tensile Strength

≥ 480 MPa

Room temperature; ≥ 820 MPa (-200°C)

Yield Strength (0.2% Offset)

≥ 170 MPa

Room temperature; ≥ 650 MPa (-200°C)

Elongation

≥ 45%

Room temperature; ≥ 35% (-200°C)

Impact Toughness (Charpy V-Notch)

≥ 200 J

-200°C; No brittle fracture at -253°C

Corrosion Resistance

Passes 1000-hour salt spray test (ASTM B117); Resists 5% H₂SO₄ (room temperature, no pitting)

5% NaCl solution, 35°C; Dilute sulfuric acid

3. Production Process of Nickel 200 Wire

The manufacturing of Nickel 200 wire requires precise control of nickel purity and impurity levels, alongside optimized processing to preserve its corrosion resistance, conductivity, and ductility. Key steps include:

3.1 Raw Material Melting & Casting (High-Purity Focus)

Melting: High-purity nickel (99.99% pure) is melted via vacuum induction melting (VIM) or air induction melting with argon degassing (AIM-AD). This process ensures controlled carbon content (≤0.15 wt%), eliminates gaseous impurities (H₂ < 5 ppm, O₂ < 10 ppm), and removes non-metallic inclusions—critical for consistent corrosion performance and conductivity.

Casting: Molten alloy is cast into small-diameter ingots (200 - 500 kg) to minimize segregation, which undergo homogenization annealing at 1050 - 1100°C for 6 - 8 hours. This step eliminates microsegregation of impurities, refines the austenitic microstructure, and dissolves any residual trace carbides—preparing the material for hot working.

3.2 Hot Working & Wire Rod Production

Hot Forging & Rolling: Ingots are hot-forged at 950 - 1050°C into billets, then hot-rolled into wire rods (diameter: 6 - 15 mm). Hot working is performed in a protective atmosphere (argon or nitrogen) to prevent oxidation (critical for maintaining low oxygen content); rods are water-quenched to room temperature to preserve the fine-grained austenitic structure and avoid excessive carbide formation.

Descaling: Hot-rolled rods undergo ultrasonic cleaning followed by acid pickling (dilute nitric acid) to remove any surface oxides—avoiding inclusions that could degrade corrosion resistance or conductivity.

3.3 Cold Drawing (Wire Formation)

Multi-Pass Cold Drawing: Wire rods are cold-drawn through diamond dies in 7 - 11 passes to achieve the desired diameter (typically 0.05 mm - 5 mm). Each pass reduces diameter by 12 - 18%, with intermediate annealing (950 - 1000°C for 30 - 45 minutes, air-cooled) between passes. This annealing step relieves work hardening, restores ductility, and ensures no excessive carbide precipitation—critical for maintaining conductivity and corrosion resistance.

Dimensional Control: Laser diameter monitoring is used throughout drawing to maintain tight tolerance (±0.01 mm for precision wire)—critical for components like thermocouple sheaths and electrical connectors, where dimensional variations affect performance (e.g., temperature measurement accuracy, current transmission).

3.4 Final Heat Treatment (Stability & Performance Optimization)

Nickel 200 wire undergoes a specialized heat treatment to maximize its key properties:

Solution Annealing: Heating the wire to 1000 - 1050°C for 1 - 2 hours, followed by rapid water quenching. This step dissolves any residual trace carbides, ensures a uniform austenitic microstructure, and eliminates work hardening from cold drawing—critical for maintaining corrosion resistance and ductility.

Stress Relief (Optional): For components used in cyclic loading or cryogenic applications, the wire is heated to 600 - 650°C for 1 - 2 hours, then air-cooled. This step relieves residual stresses from cold drawing, reducing the risk of stress corrosion cracking (SCC) in service.

3.5 Surface Finishing & Quality Inspection

Surface Treatment:

Electropolishing: For high-precision or electrical applications, the wire undergoes electropolishing in a sulfuric-nitric acid solution to achieve a smooth surface finish (Ra ≤ 0.1 μm). This removes surface defects, reduces contact resistance (for electrical connectors), and eliminates contamination.

Passivation: Optional nitric acid passivation to enhance resistance to atmospheric corrosion during storage and handling, without compromising conductivity.

Cleaning: For chemical or food-grade applications, the wire is cleaned with ultra-pure solvents (isopropyl alcohol, deionized water) to remove all contaminants, meeting industry-specific purity standards.

Quality Control:

Chemical Analysis: Glow discharge mass spectrometry (GDMS) to verify nickel purity (≥99.0 wt%) and impurity levels (Fe, O₂, C) meet specifications.

Mechanical Testing: Tensile and impact testing at room temperature and -200°C; fatigue testing (10⁸ cycles) to validate cyclic performance for springs or connectors.

Corrosion Testing: Salt spray testing (ASTM B117) and immersion testing in 5% H₂SO₄ (room temperature) to confirm corrosion resistance.

Non-Destructive Testing: Eddy current testing (for surface defects like cracks or pits) and ultrasonic testing (for internal flaws); magnetic flux leakage testing to confirm non-ferromagnetic properties.

Dimensional Inspection: Coordinate measuring machine (CMM) for precision wire to confirm diameter, straightness (≤0.1 mm/m), and roundness.

Conductivity Testing: Four-point probe testing to verify electrical resistivity (meets ≤0.069 × 10⁻⁶ Ω·m at 25°C) for electrical applications.

4. Product Applications

Nickel 200 wire’s exceptional combination of corrosion resistance, thermal/electrical conductivity, and cryogenic toughness makes it indispensable in diverse industries:

4.1 Chemical Processing & Petrochemical Industry

Corrosion-Resistant Components: Fine wire (0.2 - 1.0 mm) for thermocouple sheaths, sensor probes, and wire mesh filters in sulfuric acid (H₂SO₄), nitric acid (HNO₃), and acetic acid production—resists both oxidizing and reducing acids at moderate temperatures.

Chlor-Alkali Industry: Wire for electrolyzer components (e.g., cathode leads) and brine handling equipment—resists corrosion from sodium chloride brines and chlorine gas, ensuring long service life.

Pharmaceutical Manufacturing: Sanitary wire for mixing blades and filtration systems—complies with FDA standards (21 CFR Part 177) for food/drug contact, and high purity avoids product contamination.

4.2 Electronics & Electrical Engineering

High-Conductivity Connectors: Wire for electrical connectors in aerospace, automotive, and industrial electronics—low electrical resistivity (0.069 × 10⁻⁶ Ω·m at 25°C) ensures efficient current transmission, even at low temperatures.

Thermal Management: Wire for heat exchanger tubes and cooling loops in high-power electronics (e.g., LED arrays, power inverters)—excellent thermal conductivity (90.9 W/(m·K) at 25°C) efficiently dissipates heat.

Thermocouple Extensions: Wire for Type K or Type T thermocouple extensions—compatible with standard thermocouple materials and provides accurate temperature measurement up to 315°C.

4.3 Cryogenic Engineering & Energy Storage

Liquid Nitrogen (LN₂) Systems: Wire for LN₂ storage tank sensors and valve stems—maintains ductility at -196°C and resists corrosion from liquid nitrogen.

Cryogenic Fasteners: Wire for small-diameter rivets and bolts in cryogenic equipment (e.g., freeze-dryers)—combines cryogenic toughness with good formability, avoiding brittle fracture at low temperatures.

Superconducting Support Components: Wire for structural supports in low-temperature superconducting systems—non-ferromagnetic properties avoid interfering with magnetic fields, and high purity reduces current loss.

4.4 Aerospace & Defense

Aerospace Electrical Systems: Wire for aircraft wiring harnesses and satellite power systems—resists corrosion from jet fuel vapors and space vacuum, and maintains conductivity at extreme temperature cycles (-60°C to 150°C).

Military Equipment: Wire for sensor cables in military vehicles and communication devices—resists environmental corrosion (salt spray, humidity) and provides reliable performance in harsh field conditions.

4.5 Marine Engineering & Consumer Goods

Marine Electrical Components: Wire for boat wiring and underwater sensor cables—resists seawater corrosion (3.5% NaCl) and biofouling, extending service life in marine environments.

Consumer Electronics: Wire for high-end audio cables and precision instruments—high purity ensures minimal signal interference, and corrosion resistance maintains performance over time.

Conclusion

Alloy 200 (Nickel 200 Wire, UNS N02200) is a foundational high-purity nickel alloy wire, distinguished by its exceptional corrosion resistance, thermal/electrical conductivity, and cryogenic toughness. Its balanced chemistry and straightforward manufacturing process (no age hardening required) make it a reliable, cost-effective choice for applications in chemical processing, electronics, and cryogenic engineering—where standard metals fail due to corrosion, brittleness, or poor conductivity. While its slightly higher carbon content requires caution in hydrogen-rich environments, its performance in mild to moderate aggressive conditions remains unmatched. For custom requirements—such as ultra-fine wire (down to 0.01 mm diameter) for microelectronics, high-conductivity variants for power applications, or large-diameter wire (up to 8 mm) for structural components—manufacturers offer tailored solutions to meet the most demanding corrosion, conductivity, or low-temperature challenges. As the original pure nickel alloy, it continues to be a go-to material for industries where reliability and performance are non-negotiable.

Packing of Standard Packing: 

Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 625 gallon liquid totes Special package is available on request.