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Hastelloy C-22/UNS N06022/W. Nr. 2.4602/Alloy C-22 bar

Hastelloy C-22 bar, designated under the unified numbering system as UNS N06022, material number W.Nr. 2.4602, and commonly known as Alloy C-22, is a …

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Hastelloy C-22 bar, designated under the unified numbering system as UNS N06022, material number W.Nr. 2.4602, and commonly known as Alloy C-22, is a versatile nickel-chromium-molybdenum-tungsten alloy engineered for outstanding corrosion resistance in a wide spectrum of aggressive chemical environments, including both oxidizing and reducing conditions. This bar stock form is a premier choice for machining critical components such as pump shafts, valve stems, agitators, and fasteners used in the most demanding sectors of chemical processing, pollution control, and pharmaceutical industries, where reliability and longevity are paramount.

Table of Contents Hide

1 Introduction to Hastelloy C-22 (Alloy C-22)

2 Chemical Composition of Hastelloy C-22 Bar

3 Mechanical Properties of Hastelloy C-22 Bar

4 Physical Properties of Hastelloy C-22 Bar

5 Standard Specifications, Bar Forms, and Available Sizes

6 Primary Applications of Hastelloy C-22 Bar Stock

7 Corrosion Resistance Overview

8 Machining and Fabrication of Hastelloy C-22 Bar

9 Welding of Hastelloy C-22 Bar

10 Reference Pricing and Key Purchasing Factors

Hastelloy C-22

Introduction to Hastelloy C-22 (Alloy C-22)

Hastelloy C-22 is often described as a “forgiving” alloy due to its balanced composition, which provides exceptional resistance to localized corrosion (pitting and crevice corrosion), stress corrosion cracking, and uniform attack across a broad pH range. It was developed to offer improved thermal stability and weldability over earlier C-type alloys. The bar stock is ideal for fabricating parts that must withstand mixed acids, chlorides, and other harsh chemicals, often at elevated temperatures and under high stress.

Chemical Composition of Hastelloy C-22 Bar

The superior and balanced corrosion resistance of Hastelloy C-22 bar is a direct result of its optimized chemistry. Supplied by Shanghai NC Metal Materials Co., Ltd., the bar stock meets exacting international standards to ensure consistent performance in critical service.

Element	Percentage (%) – Typical Range	Primary Function in the Alloy
Nickel (Ni)	Balance (≥ 50.0)	Base element; provides the austenitic matrix and fundamental resistance to reducing environments and stress corrosion cracking.
Chromium (Cr)	20.0 – 22.5	Confers excellent resistance to oxidizing media such as nitric acid, ferric and cupric salts, dissolved oxygen, and hypochlorite.
Molybdenum (Mo)	12.5 – 14.5	Provides primary resistance to reducing acids (e.g., hydrochloric, sulfuric) and is critical for preventing pitting and crevice corrosion in halide solutions.
Tungsten (W)	2.5 – 3.5	Enhances resistance to reducing acids and complements molybdenum in improving localized corrosion resistance.
Iron (Fe)	2.0 – 6.0	Controlled addition; provides solid-solution strengthening and helps balance cost.
Cobalt (Co)	2.5 max	Residual/controlled element.
Vanadium (V)	0.35 max	Residual element.
Carbon (C)	0.015 max	Kept extremely low to prevent sensitization (chromium carbide precipitation) during welding, preserving corrosion resistance.
Manganese (Mn)	0.50 max	Residual element, deoxidizer.
Silicon (Si)	0.08 max	Kept very low to prevent the formation of detrimental phases and maintain thermal stability.
Phosphorus (P)	0.02 max	Impurity control.
Sulfur (S)	0.02 max	Impurity control for hot workability and corrosion resistance.

Mechanical Properties of Hastelloy C-22 Bar

Hastelloy C-22 bar offers a robust combination of high strength and excellent ductility, suitable for demanding mechanical applications in corrosive settings. It is typically supplied in the solution-annealed condition.

Mechanical Property	Typical Value at Room Temperature (Annealed)	ASTM B574 (UNS N06022) Minimum Requirement	Key Characteristic
Tensile Strength	690 – 830 MPa (100 – 120 ksi)	≥ 690 MPa (100 ksi)	High strength for structural components in aggressive environments.
Yield Strength (0.2% Offset)	310 – 415 MPa (45 – 60 ksi)	≥ 310 MPa (45 ksi)	–
Elongation in 2 inches (50mm)	≥ 45%	≥ 40%	Excellent ductility, facilitating complex machining and providing good toughness.
Hardness (Rockwell B)	85 – 100 HRB	–	–
Reduction of Area	≈ 50%	–	–

Physical Properties of Hastelloy C-22 Bar

The physical properties of Alloy C-22 bar are important for engineering design involving thermal management, electrical properties, and weight considerations in chemical plant equipment.

Physical Property	Value at Room Temperature (20°C / 68°F)	Notes / Condition
Density	8.69 g/cm³ (0.314 lb/in³)	–
Melting Range	1357 – 1399°C (2475 – 2550°F)	–
Specific Heat	≈ 410 J/kg·°C (0.098 BTU/lb·°F)	At 100°C
Thermal Conductivity	10.2 W/m·K (70.7 BTU·in/hr·ft²·°F)	At 100°C
Mean Coefficient of Thermal Expansion	11.5 μm/m·°C (6.4 μin/in·°F)	20-100°C (68-212°F)
Electrical Resistivity	1.25 μΩ·m (49.2 μΩ·in)	At 20°C
Modulus of Elasticity (Tensile)	206 GPa (29.9 x 10^6 psi)	At 20°C

Standard Specifications, Bar Forms, and Available Sizes

Shanghai NC Metal Materials Co., Ltd. supplies Hastelloy C-22 bar in various forms to meet the rigorous demands of the chemical process and related industries.

Product Form	Standard Size Range	Key Standard Specifications	Common Supply Conditions
Round Bar (Hot Rolled/Forged)	10mm (0.4″) to 300mm (12″) Diameter	ASTM B574 (UNS N06022), ASME SB-574, NACE MR0175/ISO 15156, DIN 17744 (W.Nr. 2.4602)	Solution Annealed (typically 1120-1160°C water quench)
Hexagonal Bar	10mm to 80mm Across Flats	ASTM B574, DIN 17744	Solution Annealed
Square Bar	10mm to 80mm Width	ASTM B574	Solution Annealed
Cold Finished Bar (Drawn/Ground)	5mm to 120mm Diameter	ASTM B574 (cold drawn)	Solution Annealed, Cold Drawn & Stress-Relieved
Forging Billet	150mm to 400mm Diameter	ASTM B564 (Forgings), Customer forging specs	As-Forged, Solution Annealed

Primary Applications of Hastelloy C-22 Bar Stock

Machined components from Hastelloy C-22 bar are essential in severe corrosive service: Chemical Processing: Reactor vessels, heat exchanger tubesheets, agitator shafts, pump components, and valve internals exposed to mixed acids (e.g., sulfuric/nitric), chlorine, formic/acetic acid, and chloride-containing brines. Flue Gas Desulfurization (FGD): Critical components in scrubbers, fans, ducting, and reheaters handling wet, chloride-laden acidic gases. Pharmaceutical & Fine Chemical: Equipment for synthesis where high purity and resistance to aggressive cleaning agents (like hypochlorite) are required. Waste Treatment & Incineration: Heat exchangers and components in waste acid recovery and incineration systems.

Corrosion Resistance Overview

Hastelloy C-22 offers one of the broadest corrosion resistance profiles available. It excels in both oxidizing and reducing environments. It handles hot contaminated mineral acids (sulfuric, hydrochloric, phosphoric), sour gas (H2S/CO2/chlorides), formic and acetic acids, and seawater. Its resistance to localized attack is exceptional, with very high Critical Pitting Temperature (CPT) and Critical Crevice Temperature (CCT) in chloride solutions. It also resists stress corrosion cracking in chloride and polythionic acid environments. This balanced performance makes it a first-choice material for handling unknown or fluctuating process conditions.

Machining and Fabrication of Hastelloy C-22 Bar

Hastelloy C-22 bar is machinable using techniques for tough, work-hardening nickel alloys. Recommendations include: using rigid, high-power machine tools; sharp carbide or ceramic cutting tools with positive rake angles; moderate cutting speeds; firm, consistent feed rates to minimize work hardening; and high-pressure coolant for heat dissipation and chip control. Its high strength and work-hardening rate necessitate avoiding tool dwelling and using sharp tools at all times.

Welding of Hastelloy C-22 Bar

Alloy C-22 is designed for excellent weldability. It can be welded using all common fusion welding processes, including Gas Tungsten Arc Welding (GTAW/TIG), Shielded Metal Arc Welding (SMAW/Stick), and Gas Metal Arc Welding (GMAW/MIG). Matching filler metals (e.g., ERNiCrMo-10) are recommended. Due to its very low carbon content and balanced composition, it is highly resistant to sensitization and the formation of detrimental secondary phases in the weld heat-affected zone (HAZ). Post-weld heat treatment is not typically required for corrosion resistance in most applications.

Reference Pricing and Key Purchasing Factors

The price of Hastelloy C-22 bar from Shanghai NC Metal Materials Co., Ltd. is influenced by its high nickel, chromium, and molybdenum content, as well as the stringent impurity controls and premium associated with its top-tier corrosion performance.

Pricing Factor	Impact on Reference Price	Procurement Guidance
Alloying Element Costs (Ni, Cr, Mo, W)	The combined high content of nickel, chromium, molybdenum, and tungsten forms a significant portion of the base price, making it one of the more expensive high-performance alloys.	Its cost is justified in applications where failure of a lesser material would lead to severe safety risks, production downtime, or environmental incidents.
Ultra-Low Impurity Specification	The requirement for extremely low carbon, silicon, phosphorus, and sulfur levels necessitates specialized melting and refining processes (e.g., VIM, AOD, ESR), adding to manufacturing cost.	Ensure the supplier’s Mill Test Report confirms compliance with the tight compositional limits of ASTM B574, especially for welded construction.
Industry Certification	Bar supplied with NACE MR0175/ISO 15156 certification for sour service, or for use in ASME pressure vessels, may carry a premium over standard stock.	Specify the necessary industry certifications at the time of inquiry to ensure the material is suitable for the intended service environment (e.g., oil & gas, chemical plant).
Testing and Documentation	Requirements for extensive corrosion testing (e.g., ASTM G28 Method A for intergranular corrosion, ASTM G48 for pitting), full traceability, or special NDE (ultrasonic testing of bar) add cost and lead time.	Define the exact testing and documentation package required. For many applications, a standard EN 10204 3.1 certificate with chemistry and mechanical properties is sufficient.

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