The Industrial Cornerstone of Pure Nickel: Nickel 200 (UNS N02200) Alloy Tubes – A Comprehensive Overview

---

Chapter I: Introduction—Definition, Historical Status, and Core Value of Commercially Pure Nickel

1.1 The Significance of Commercially Pure Nickel and the Genesis of Nickel 200

In today’s highly specialized and demanding industrial production environments, material performance requirements extend far beyond basic mechanical strength. When facing aggressive chemical corrosion, specialized electrical/thermal needs, and stringent product purity standards, ordinary metallic materials often prove inadequate. It is in this context that Nickel-Base Alloys, particularly Nickel 200 (UNS N02200), renowned as “Commercially Pure Nickel,” have established themselves as an indispensable foundation for numerous critical industrial processes, thanks to their unique combination of high chemical purity and outstanding properties.

Nickel 200 is not a new innovation; its history traces back to the 1930s, initially developed by the former International Nickel Company (Inco). It represents one of the highest purity nickel alloys commercially available, typically requiring a nickel content of no less than \(99.0\%\). This exceptional purity endows it with a unique set of physical and chemical characteristics, notably its unmatched stability and resistance to corrosion in aggressive caustic alkaline media—a position it holds unyieldingly in the critical chemical processing sector.

Our company specializes in the R&D and manufacture of Nickel 200 / UNS N02200 Nickel Alloy Tubes. As a critical component for fluid transfer, heat exchange, and structural support, the quality of our tubing directly determines the reliability and service life of the entire system. We recognize that manufacturing a compliant Nickel 200 tube is not merely a metal forming process; it is a systemic undertaking involving metallurgy, precision machining, non-destructive testing (NDT), and stringent quality control. We provide more than just metal tubes; we offer a long-term commitment to industrial continuity, product purity, and safety, rooted in a deep understanding of materials science and an uncompromising pursuit of manufacturing excellence.

1.2 Key Technical Distinction: Nickel 200 vs. Nickel 201 and the Temperature Boundary

Before delving into the performance specifics of Nickel 200, it is crucial to clarify the significant difference between it and its lower-carbon counterpart, Nickel 201 (UNS N02201). This distinction represents a vital technical criterion for alloy selection:

• Nickel 200 (UNS N02200): Carbon content is controlled up to a maximum of \(0.15\%\).
• Nickel 201 (UNS N02201): Carbon content is strictly controlled to be below \(0.02\%\).

This seemingly minor difference in carbon content leads to a major divergence in application performance: Nickel 200 is susceptible to graphitization or sensitization (intergranular carbide precipitation) when exposed to temperatures exceeding \(315^\circ \text{C}\) (\(600^\circ \text{F}\)) for extended periods, which increases its sensitivity to intergranular corrosion. Therefore, **Nickel 200 is primarily recommended by metallurgical engineers for service environments below \(315^\circ \text{C}\)**.

Nickel 201 was specifically designed to overcome this high-temperature sensitization issue and is **suitable for environments above \(315^\circ \text{C}\)**, ensuring the material maintains its corrosive integrity at elevated operating temperatures. As a professional tube manufacturer, we meticulously control the chemical composition of raw materials and can flexibly supply either Nickel 200 or Nickel 201 based on the client’s specific operating temperature and application requirements, ensuring scientific and appropriate material selection.

---

Chapter II: Deep Dive into Nickel 200 Alloy Material Science: The Logic of Purity and Performance

2.1 Chemical Composition: Purity as the Foundation of Performance

The core value of Nickel 200 lies in its chemical purity. The high-purity nickel matrix not only guarantees its excellent corrosion resistance but also delivers unique functional physical properties, such as high electrical conductivity and ferromagnetism. Table 1 details the primary chemical composition requirements stipulated by the UNS N02200 standard (referencing ASTM B163/B161), which serves as the mandatory benchmark for our tube production:

Element	UNS N02200 Standard (ASTM B163/B161) Max Content (%)	Significance and Impact
Nickel (Ni) + Cobalt (Co)	Min. \(99.00\)	Ensures primary corrosion resistance, high ductility, conductivity, and magnetostrictive properties.
Carbon (C)	Max. \(0.15\)	Affects intergranular corrosion sensitivity (sensitization) at high temperatures. High C content is the key differentiator from Ni 201.
Copper (Cu)	Max. \(0.25\)	Strictly controlled to avoid compromising pure nickel’s stability in caustic alkali solutions.
Iron (Fe)	Max. \(0.40\)	Impurity element, affects purity, electrical conductivity, and magnetic properties. High \(\text{Fe}\) content reduces conductivity.
Manganese (Mn)	Max. \(0.35\)	Common deoxidizer, controlled to maintain purity and affects weldability.
Silicon (Si)	Max. \(0.35\)	Common deoxidizer, excessive content reduces ductility.
Sulfur (S)	**Max. \(0.01\)**	**Must be extremely low.** Sulfides severely impair high-temperature toughness, weldability, and corrosion resistance, easily causing hot shortness.
Others	Max. \(0.10\)	Control of total residual impurities to ensure overall high purity.

Table 1: Chemical Composition Requirements for Nickel 200 (UNS N02200) Alloy Tubes

2.2 Physical Properties: The Basis for Functional Applications

The physical properties of high-purity nickel alloy make it unique across many sectors, particularly in electrical transmission and thermodynamics. Nickel 200 is ferromagnetic (below its Curie Temperature of about \(360^\circ \text{C}\)) and possesses high thermal and electrical conductivity, an advantage many other nickel-based superalloys lack.

Physical Property	Typical Value	Unit	Notes
Density	\(8.89\)	\(\text{g/cm}^3\)	Relatively heavy, reflecting the high-density packing of nickel atoms.
Melting Range	\(1435 – 1446\)	\(\text{^\circ \text{C}}\)	High melting point, lending good thermal stability for high-temperature applications.
Curie Temperature	\(360\)	\(\text{^\circ \text{C}}\)	Exhibits ferromagnetism below this temperature.
Thermal Expansion Coefficient	\(13.3 \times 10^{-6}\)	\(\text{K}^{-1}\)	Average value between \(20^\circ \text{C}\) and \(100^\circ \text{C}\).
Thermal Conductivity	\(70.2\)	\(\text{W/(m}\cdot\text{K)}\)	Value at \(21^\circ \text{C}\). Better than stainless steel and many Ni-Cr alloys, beneficial for heat exchange.
Electrical Conductivity	\(\approx 15 – 20\)	\(\%\) IACS	Significantly higher than most nickel alloys, approaching the conductivity of copper, ideal for electronic applications.
Modulus of Elasticity	\(205\)	\(\text{GPa}\)	Reflects the material’s stiffness, comparable to steel.

Table 2: Typical Physical Properties of Nickel 200 Alloy Tubes

2.3 Mechanical Properties: Customization through Cold Work and Annealing

As a commercially pure nickel, Nickel 200 features excellent ductility and good cold-working characteristics, making it easy to perform precision cold drawing and rolling—a crucial requirement for manufacturing thin-walled, high-precision tubes. The final mechanical properties of the tube are largely dependent on its final heat treatment (e.g., annealed or cold-drawn condition).

Table 3 lists the general mechanical property targets for **Annealed** Nickel 200 tubes, parameters that must be verified through tensile testing within our quality control system:

Mechanical Property	Annealed Typical Value	Unit	ASTM B163 Minimum Requirement (Min.)
Tensile Strength	\(400 – 550\)	\(\text{MPa}\)	\(380\)
Yield Strength (0.2% Offset)	\(105 – 200\)	\(\text{MPa}\)	\(105\)
Elongation	\(45 – 60\)	\(\%\)	\(35\)
Rockwell Hardness	\(60 – 75\)	\(\text{HRB}\)	–

Table 3: Mechanical Property Targets for Nickel 200 Alloy Tubes (Annealed Condition)

Through precise control of the cold working reduction ratio and subsequent annealing process, we can tailor the tube’s final temper. For instance, the Cold Drawn condition can significantly increase its Yield Strength (up to \(450 \text{MPa}\) or more) at the cost of some ductility, making it suitable for applications requiring higher structural strength. This precise capability to tune the final mechanical properties highlights our depth of expertise in tube manufacturing.

---

Chapter III: Deep Dive into the Superior Corrosion Resistance of Nickel 200

3.1 The “Corrosion King” in Caustic Alkaline Media: Core Competency

Nickel 200 earns its reputation as the “Corrosion King” primarily from its unmatched resistance to corrosion in Caustic Alkalis such as Sodium Hydroxide (\(\text{NaOH}\)) and Potassium Hydroxide (\(\text{KOH}\)). These aggressive chemicals, even at high concentrations and temperatures, severely attack most stainless steels and Nickel-Chromium-Iron alloys.

Nickel 200’s Corrosion Resistance Mechanism: The surface of nickel rapidly forms a thin, dense, and highly stable passive oxide film (\(\text{NiO}\)). This oxide film is chemically inert and extremely stable in strong alkaline solutions. It effectively isolates the metal substrate from the corrosive medium, providing superior, long-term corrosion protection. The stability of this passive film is the crucial factor that allows Nickel 200 to outperform other alloys.

• Caustic Soda (\(\text{NaOH}\)) Applications: Nickel 200 exhibits excellent performance in nearly all concentrations and temperatures of \(\text{NaOH}\) solutions. In the Chlor-Alkali industry, where water is evaporated to concentrate \(\text{NaOH}\), Nickel 200 tubes are the **standard material of choice** for heating and evaporator tubes, guaranteeing long equipment life and the purity of the \(\text{NaOH}\) product.
• **Reiterating High-Temperature Limits:** The \(315^\circ \text{C}\) temperature limit is vital. For high-temperature caustic service above this threshold, we **strongly recommend** using the ultra-low carbon Nickel 201 to mitigate the risk of sensitization and ensure the safety of long-term operation.

3.2 Complex Behavior in Acidic Environments and Aqueous Media

Nickel 200’s acid resistance is selective and highly dependent on the type of acid and the oxidation state of the solution:

1. **Reducing Acids:** In non-oxidizing and de-aerated solutions of Hydrochloric Acid (\(\text{HCl}\)) and Sulfuric Acid (\(\text{H}_2\text{SO}_4\)), Nickel 200 possesses some tolerance. The critical condition is de-aeration. The presence of even trace amounts of oxygen or oxidizing agents (like \(\text{Fe}^{3+}\) ions) will break down the passive film formed in the reducing environment, causing a sharp increase in the corrosion rate.
2. **Oxidizing Acids:** Nickel 200 **is unsuitable** for strong oxidizing acids such as Nitric Acid (\(\text{HNO}_3\)) or concentrated Sulfuric Acid. In these media, the corrosion rate is prohibitively high. Higher Cr or Mo containing alloys (like \(\text{Inconel}\) or \(\text{Hastelloy}\) series) are typically required here.
3. **Aqueous Media and Salt Water:** In neutral and alkaline salt solutions, as well as stationary or low-velocity fresh water, corrosion resistance is good. However, in high-velocity seawater or in stagnant areas with deposits, the risk of Pitting and Crevice Corrosion increases. For applications requiring better seawater resistance, alloys with higher resistance to chloride ions, like \(\text{Ni-Cu}\) series alloys (\(\text{Monel 400}\)), are often chosen.

3.3 Resistance to Dry Halogen Gases and High-Temperature Oxidation

• **Dry Halogens:** At high temperatures, Nickel 200 shows good corrosion resistance in dry halogen gases such as Chlorine (\(\text{Cl}_2\)) and Fluorine (\(\text{F}_2\)). However, this requires the atmosphere to be **absolutely dry**, as the presence of moisture significantly accelerates the corrosion reaction.
• **High-Temperature Oxidation:** In dry, oxidizing air, Nickel 200’s resistance to oxidation is good, usable up to about \(1200^\circ \text{C}\). However, if the environment introduces **sulfur compounds** or **reducing gases**, the high-temperature performance of the nickel-based material is severely compromised. Nickel reacts with sulfur to form low-melting-point nickel sulfides, potentially leading to **Hot Shortness**.

---

Chapter IV: Precision Manufacturing and Quality Assurance System for Nickel 200 Tubes

4.1 Manufacturing Process: From Billet to High-Precision Seamless Tube

Our company is committed to manufacturing high-quality Nickel 200 Seamless and Welded Tubes. Seamless tubes, due to their superior wall thickness uniformity, higher structural integrity, and pressure-bearing capacity, are the ideal choice for critical pressure and high-temperature applications.

4.1.1 Seamless Tube Manufacturing: The Art of Cold Working

Manufacturing \(\text{Nickel 200}\) seamless tubes is a complex, multi-step cold working process demanding extreme precision:

1. **Raw Material Preparation and Analysis:** Start with solid round billets (Billet) that have been strictly melted and analyzed, meeting the \(\text{UNS N02200}\) requirements. This is the first step in ensuring product purity.
2. **Piercing/Hot Extrusion:** The solid billet is heated and rotary pierced or processed via extrusion to create an initial thick-walled shell.
3. **Cold Drawing or Cold Rolling:** This is the **core step** for manufacturing precision Nickel 200 tubes. Through repeated cold drawing/rolling cycles, the tube is gradually reduced in diameter and wall thickness. This process significantly improves the surface finish and dimensional accuracy while introducing **work hardening** that enhances mechanical strength.
4. **Intermediate and Final Annealing:** Because Nickel 200 hardens rapidly during cold work, intermediate and final annealing are essential. **Purpose:** To restore the metal’s ductility, relieve internal stresses, and allow the tube to be further processed or brought to its final required softened state. **Key Requirement:** Annealing must be performed in a **strictly controlled inert or hydrogen atmosphere** (e.g., **Bright Annealing, BA**) to prevent surface oxidation and maintain a clean, high-luster finish.
5. **Finishing and Surface Treatment:** After final sizing, the tubes undergo pickling or mechanical/chemical polishing to remove any residual surface oxides and contaminants, achieving the smooth surface finish (\(\text{Ra}\) value) required by the customer.

4.1.2 Welded Tube Manufacturing: High-Purity Fusion

Welded tubes are formed by rolling high-purity Nickel 200 strip into a tubular shape and then using a continuous Gas Tungsten Arc Welding (\(\text{GTAW/TIG}\)) process to fuse the longitudinal seam with high purity. Welded tubes often undergo subsequent cold work and annealing to eliminate weld stresses and improve geometric dimensions. They are suitable for non-high-pressure, non-critical fluid transfer due to their cost-effectiveness and dimensional flexibility.

4.2 Stringent Quality Control and Non-Destructive Testing (NDT) System

For \(\text{Nickel 200}\) tubes used in critical, aggressive environments, a robust Quality Control system is the lifeline ensuring product reliability. Our quality system strictly adheres to \(\text{ISO 9001}\) and fully complies with international standards such as $\text{ASTM}$, $\text{ASME}$, and $\text{PED}$.

Inspection Item	Method	QC Objective
**Chemical Composition**	Spectroscopy, Wet Chemistry	Ensure \(\text{Ni} \ge 99.0\%\) and that impurities like \(\text{C}\) and \(\text{Fe}\) meet \(\text{UNS N02200}\) standards. This is the first critical checkpoint.
**Geometric Dimensions**	CMM, Precision Laser Measurement	Strict control over OD, wall thickness (WT), ovality, straightness, and length tolerances.
**Surface Defects**	Visual Inspection, Liquid Penetrant Test (PT)	Check for cracks, scratches, folds, and delamination to ensure surface integrity.
**Internal Defects**	Ultrasonic Testing (UT), Eddy Current Testing (ET)	Detect internal inclusions, voids, lack of weld penetration, and other hidden flaws, ensuring structural soundness.
**Pressure Integrity**	Hydrostatic Test, Pneumatic Test	Verify the structural integrity and leak-tightness under specified internal pressure—mandatory for pressure vessel applications.
**Mechanical Properties**	Tensile Test, Flattening Test, Hardness Test	Verify that tensile strength, yield strength, elongation, and ductility meet standard requirements and custom needs.
**Intergranular Corrosion**	Intergranular Corrosion Test (e.g., ASTM A262 Practice C)	Ensure no sensitization has occurred in the heat-affected zones after annealing or welding; especially critical for \(\text{Ni} 201\).

Table 4: Key Quality Control and Non-Destructive Testing Items for Nickel 200 Tubes

We provide comprehensive Material Test Reports (MTRs) for every batch of tubes, including $3.1$ or \(3.2\) certificates (certified by independent third-party inspection agencies like $\text{TUV/SGS}$ upon request), ensuring Full Traceability from raw material to final product. This is a serious commitment to our global high-end clientele.

---

Chapter V: Key Industrial Applications and Economic Considerations of Nickel 200 Tubes

5.1 Chemical and Petrochemical Industries: The Heart of Caustic Handling

This is the primary and most critical market for Nickel 200, centered on its superior resistance to caustic alkalis:

1. **Caustic Soda Production:** **Evaporator Tube Bundles:** In the Chlor-Alkali industry, concentrating \(\text{NaOH}\) solution is a core step involving high-temperature evaporation. Nickel 200/201 tubes, due to their unparalleled \(\text{NaOH}\) corrosion resistance, are widely used to manufacture heating and evaporator tubes, guaranteeing long equipment life and the purity of the \(\text{NaOH}\) product. **Heat Exchangers and Reactors:** Piping and equipment for transferring and processing other high-concentration alkaline chemicals, such as \(\text{KOH}\).
2. **Organic Processing:** Nickel 200 resists mild corrosion while preventing metallic ion contamination when processing organic chemicals like fatty acids, phenols, and methanol, or during petroleum refining processes like asphalt desulfurization.

5.2 Electronics and Electrical Industries: The Value Chain of High Conductivity

High electrical conductivity is the key factor enabling Nickel 200’s role in the electronics sector, making it a high-performance conductive material:

1. **Lithium Battery/Power Connections and Casings:** In high-power lithium-ion or Ni-Cd batteries, Nickel 200 tubes (or foil) are used as current leads, battery casings, or internal connectors, leveraging their low electrical resistance and excellent weldability for reliable current transmission.
2. **Electro-Vacuum Devices and Heating Elements:** Nickel 200 is used as structural support or electron-emitting components in vacuum tubes, cathode ray tubes, and precision resistors, capitalizing on its low evaporation rate, high melting point, and good conductivity.

5.3 Food Processing and Pharmaceutical Industries: The Ultimate Demand for Purity

In health-related industries, material corrosion products must be extremely low to prevent contamination:

1. **Food-Grade Equipment:** Piping and heat exchangers used to process fatty acids, glycerin, and high-purity water. Nickel 200’s chemical stability ensures the purity of the final food product, meeting standards like $\text{FDA}$ and $\text{USP}$.
2. **Pharmaceutical Synthesis:** In specific drug synthesis, distillation, and crystallization processes, Nickel 200 tubes are used in reactors and transfer systems to avoid metallic ion contamination, protecting sensitive catalysts and end-products.

5.4 Economic Considerations: Total Life Cycle Cost (TLC) Advantage

Although the initial procurement cost of a nickel alloy like Nickel 200 is higher than standard stainless steel, it offers a superior Total Life Cycle Cost (\(\text{TLC}\)) advantage in aggressive service conditions:

1. **Minimizing Downtime:** In the caustic alkali industry, any unexpected equipment corrosion failure leads to costly downtime and production losses. Nickel 200’s ultra-long service life means significantly reduced frequency of maintenance and replacement, delivering economic benefits that far outweigh the initial material cost.
2. **Maintaining Production Efficiency:** Its superior thermal conductivity and resistance to fouling (especially in high-concentration \(\text{NaOH}\) evaporators) help maintain high heat exchange efficiency over time, thereby reducing energy consumption and operational costs.
3. **Reducing Contamination Risk:** In high-purity industries, a single instance of contamination can ruin an entire batch, resulting in massive economic losses. Nickel 200 ensures the cleanliness of the production process and the stability of product quality, preventing hidden costs.

---

Chapter VI: Fabrication Guidelines for Nickel 200 Tubes: The Essence of Engineering Practice

6.1 Welding Procedures: Ensuring Purity and Integrity

Nickel 200 exhibits good weldability, but stringent procedures must be followed to prevent contamination, hot cracking, and high-temperature sensitization:

1. **Cleanliness:** **This is the cardinal rule** for welding nickel alloys. The tube surface and joint bevels must be thoroughly cleaned with stainless steel brushes and solvents before welding to remove all oil, scale, paint, and markings (especially low-melting-point crayon marks). Nickel alloys are highly susceptible to low-melting-point impurities like sulfur and phosphorus, which readily cause **Hot Cracking**.
2. **Welding Method:** Recommended use of **Gas Tungsten Arc Welding (\(\text{GTAW/TIG}\))** or \(\text{MIG/GMAW}\). These methods provide inert gas shielding, minimizing oxidation and nitridation in the weld zone.
3. **Filler Metal:** The most recommended filler metals for \(\text{Ni} 200\) tubes are **\(\text{ERNi}-1\) (AWS A5.14)** or **\(\text{Ni} 208\)**. Choosing the appropriate filler metal is critical to ensuring the weld joint possesses corrosion resistance and mechanical strength matching the base metal.
4. **Post-Weld Stress Relief Annealing:** If the tube has undergone significant cold work before welding, or if there is a high concentration of stress in the weld area, **Post-Weld Stress Relief Annealing** may be considered. This reduces residual tensile stress, effectively preventing **Stress Corrosion Cracking (\(\text{SCC}\))** in specific media like hot caustic alkalis.

6.2 Machining and Cold Forming Guidelines

Due to Nickel 200’s high ductility and relatively rapid work hardening rate, special precautions must be taken during machining and cold forming:

1. **Machining:** Nickel 200 is somewhat sticky and tends to gall onto cutting tools. This requires using cutting parameters characterized by **high power, low speed, and high feed rates**. Use sharp, positive-rake, high-strength carbide tools, coupled with ample cutting fluid for adequate cooling and lubrication to carry away heat and prevent tool wear and material adhesion.
2. **Cold Forming:** Nickel 200’s excellent ductility makes it easy to perform cold forming operations such as bending, flaring, and swaging. However, because it **work hardens rapidly**, for large deformation requirements (e.g., U-bending, deep drawing), it may be necessary to perform one or more **intermediate annealing** treatments during forming to restore ductility and prevent cracking due to hardening.

---

Chapter VII: Standards Compliance, Custom Services, and Our Corporate Commitment

7.1 International Standards and Specification Compliance

Our manufactured Nickel 200 / UNS N02200 tubes strictly comply with the world’s major industrial standards and specifications. Adhering to these standards is not only a prerequisite for market access but also a demonstration of our commitment to product quality.

Standard Name	Description	Applicable Product Form
**ASTM B161**	Nickel Seamless Pipe and Tube	Thick-walled piping applications, wide size range.
**ASTM B163**	Seamless Nickel Tube for Condensers and Heat Exchangers	Thin-walled heat exchange applications, high dimensional accuracy required.
**ASME SB-161**	Corresponds to ASTM B161 for Boiler and Pressure Vessel Code	Pressure vessels and piping, requires safety certification compliance.
**ASME SB-163**	Corresponds to ASTM B163 for Boiler and Pressure Vessel Code	Pressure vessel heat exchange applications, requires safety certification compliance.
**DIN/EN 2.4066**	European standard material designation for Ni 200	European market and project applications.

Table 5: Major Applicable International Standards for Nickel 200 Alloy Tubes

Our company possesses a complete quality management system capable of issuing Material Certificates compliant with $\text{EN 10204 3.1}$, and we can coordinate with customers to obtain certification from **Third-Party Inspection Agencies (\(3.2\)) ** to ensure the global usability and credibility of our products.

7.2 Custom Services Addressing Client-Specific Needs

We deeply understand that standard specification tubes often cannot meet the requirements of all critical operating conditions. Therefore, we offer highly customized manufacturing services, working closely with clients to solve engineering challenges:

1. **Extreme Customization of Dimensions and Tolerances:** We can manufacture tubes ranging from micro-tubing to large-bore pipes, with various wall thicknesses and lengths, and tighten tolerances for specific projects to meet ultra-high precision installation demands.
2. **Special Temper Conditions:** Based on the client’s precise needs for strength, hardness, and ductility, we offer various temper conditions through customized heat treatment processes, including fully **Annealed**, **Light Cold Drawn**, or **Heavy Cold Drawn** states.

---

Chapter VIII: Metallurgical Extensions: Microstructure, Failure Analysis, and Ultra-Precision Applications

8.1 The Microstructure and Performance Logic of Nickel 200 Alloy

From a microscopic perspective, Nickel 200 is a single-phase solid solution characterized by a **Face-Centered Cubic (\(\text{FCC}\)) crystal structure**.

1. **FCC Structure and Ductility:** The \(\text{FCC}\) structure possesses multiple \(\text{Slip Systems}\), which is the fundamental reason for \(\text{Nickel 200}\)’s excellent ductility and toughness. It allows the material to undergo plastic deformation through dislocation movement under large strains without immediate brittle fracture.
2. **Work Hardening Mechanism:** Cold working (such as cold drawing) introduces a large number of **Dislocations** into the \(\text{FCC}\) lattice. These dislocations become entangled and impede one another, forming dislocation walls that obstruct further plastic flow. The macroscopic result is a significant increase in yield strength and hardness. Thus, by precisely controlling the cold working reduction and annealing temperature, we can accurately tune the tube’s final mechanical properties.

8.2 Ultra-Precision Applications for High-Purity Requirements

Leveraging ultra-precision cold working and surface treatment technology, we are capable of supplying specialty tubes beyond standard dimensions:

1. **Micro-Tubing Technology:** Manufacturing tubes with diameters smaller than \(1 \text{mm}\) and wall thicknesses less than \(0.1 \text{mm}\). This requires multi-stage ultra-precision cold drawing and customized diamond dies, all while maintaining purity above \(99.0\%\). Micro-tubing is essential for **precision sensor protective sheaths**, **medical implantable devices**, and **micro heat exchange elements**.
2. **Ultra-High Surface Finish Tubes:** Through specialized internal surface finishing (such as internal honing and **Electropolishing (\(\text{EP}\))**), the internal surface roughness (\(\text{Ra}\)) of the tube can be reduced to the nanometer level. This ultra-smooth surface effectively prevents particle retention, microbial adhesion, and scaling within the fluid, meeting the extreme cleanliness demands of **semiconductor High-Purity Fluid Delivery** and the **biopharmaceutical** industry.

---

Chapter IX: Conclusion—Guaranteeing Reliability and Purity

**Nickel 200 (UNS N02200)** alloy tubes have established themselves as an irreplaceable foundational material across various critical industries—including chemical, electronics, food, and pharmaceutical—owing to their outstanding caustic corrosion resistance, excellent electrical conductivity, good thermal stability, and favorable cold working characteristics.

Our company, backed by profound metallurgical knowledge, advanced precision manufacturing technology, and a stringent quality control system, ensures that every meter of Nickel 200 tube leaving our facility meets or exceeds international standards. We are committed to providing you with:

• A Comprehensive Product Range: Covering seamless and welded forms, various sizes, and temper conditions.
• Full Traceability: Ensuring every tube batch is accompanied by complete $3.1$ / \(3.2\) certification documents.
• Expert Technical Support: Assisting you with optimal material selection and design to maximize the performance benefits of Nickel 200.

The Nickel 200 tube is more than just a metal product; it is our steadfast commitment to industrial safety, production efficiency, and product purity. We look forward to collaborating with you to advance industrial progress.