c276 bar Hot Rolled With Solid Solution Alloy 2.4819 / UNS N10276 ASTM EN DIN GB Standard

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Regular Diameter of Hastelloy C276 Round Bar in Stock

C276 Bar Hot Rolled With Solid Solution Alloy 2.4819 / UNS N10276 ASTM EN DIN GB Standard

Abstract

Hastelloy C-276 (UNS N10276, W.Nr. 2.4819) is a nickel-chromium-molybdenum alloy renowned for its exceptional corrosion resistance in severe environments. This technical document provides a comprehensive overview of the hot-rolled solid solution treated C-276 alloy bar, detailing its chemical composition, physical and mechanical properties, applicable international standards, diverse applications, and available product forms. The information presented serves as a guide for engineers and designers selecting materials for aggressive industrial applications where resistance to both oxidizing and reducing media is required.

1 Introduction to Hastelloy C-276 Alloy

Hastelloy C-276, also known as UNS N10276 according to the Unified Numbering System and 2.4819 under the W.Nr. (Werkstoffnummer) material numbering system, is a nickel-based superalloy belonging to the Hastelloy family of materials developed by Haynes International. This alloy is specifically designed to deliver exceptional corrosion resistance in demanding industrial environments. The C-276 grade contains significant additions of molybdenum (15-17%) and chromium (14.5-16.5%), which impart outstanding resistance to both reducing and oxidizing chemicals respectively. The presence of tungsten (3-4.5%) further enhances its corrosion resistance, particularly in mixed acid environments and localized corrosion scenarios.

The alloy is characterized by its low carbon content (≤0.01% typically), which minimizes carbide precipitation during welding and thermal processing, thereby maintaining corrosion resistance in the welded condition. This combination of properties makes C-276 bars particularly suitable for fabrication into components that must withstand aggressive chemical media, high temperatures, and stress corrosion cracking environments. The hot-rolled bar form in solid solution treated condition offers optimal mechanical properties and microstructural uniformity for subsequent machining and fabrication processes.

2 Key Parameters and Properties

2.1 Chemical Composition

The chemical composition of Hastelloy C-276 is carefully balanced to achieve its renowned corrosion resistance while maintaining good mechanical properties and fabricability. The following table presents the typical chemical requirements for UNS N10276 alloy bars:

*Table 1: Chemical Composition Requirements for Hastelloy C-276 (UNS N10276)*

*Data compiled from ASTM B574/B575 standards and multiple reference sources16*

2.2 Physical Properties

Hastelloy C-276 exhibits physical properties characteristic of nickel-based alloys, with high density and moderate thermal expansion. These properties are important considerations for design calculations involving thermal cycling, weight considerations, and electrical/thermal applications:

*Table 2: Physical Properties of Hastelloy C-276 Bar*

Data from reference sources and material specifications26

2.3 Mechanical Properties

Hot-rolled C-276 bars in solid solution treated condition exhibit a combination of high strength, good ductility, and excellent impact resistance across a wide temperature range. The following table summarizes typical mechanical properties at room temperature:

*Table 3: Typical Mechanical Properties of Hot-Rolled Solid Solution Treated C-276 Bar*

Data from reference sources and material specifications256

The mechanical properties of C-276 remain relatively stable at elevated temperatures, with retained strength and oxidation resistance up to approximately 650°C (1200°F). However, prolonged exposure in the temperature range of 650-1090°C (1200-2000°F) may lead to precipitation of intermetallic phases that can reduce toughness and corrosion resistance.

2.4 Corrosion Resistance Properties

Hastelloy C-276 exhibits outstanding corrosion resistance in a wide range of aggressive media, which is its primary advantage over conventional stainless steels and many other nickel alloys:

• Reducing Environments: Excellent resistance to sulfuric acid of various concentrations, hydrochloric acid, phosphoric acid, and other reducing chemicals due to its high molybdenum content.

• Oxidizing Environments: Good resistance to oxidizing media including nitric acid, ferric chloride, cupric chloride, and chlorinated solutions due to its chromium content.

• Localized Corrosion: Exceptional resistance to pitting corrosion and crevice corrosion in chloride-containing environments, with a Pitting Resistance Equivalent Number (PREN) typically in the range of 65-75.

• Stress Corrosion Cracking (SCC): High resistance to chloride-induced stress corrosion cracking, making it suitable for demanding chemical process applications.

• Mixed Acids: Particularly useful in environments containing mixtures of oxidizing and reducing acids where other materials might fail rapidly.

The alloy is one of the few materials that can withstand wet chlorine gas, hypochlorite solutions, and chlorine dioxide environments16. It also demonstrates outstanding resistance to corrosive attack by organic acids such as formic and acetic acid, even at elevated temperatures and in the presence of impurities27.

3 Applicable Standards and Specifications

Hastelloy C-276 bars are produced according to several international standards that ensure consistency in chemical composition, mechanical properties, and dimensional tolerances. The following standards apply to hot-rolled solid solution treated bars:

3.1 ASTM (American Society for Testing and Materials) Standards

• ASTM B574: Standard Specification for Low-Carbon Nickel-Chromium-Molybdenum, Low-Carbon Nickel-Molybdenum-Chromium-Tungsten, and Low-Carbon Nickel-Chromium-Molybdenum-Copper Alloys Rod and Bar

• ASTM B575: Standard Specification for Low-Carbon Nickel-Chromium-Molybdenum, Low-Carbon Nickel-Molybdenum-Chromium-Tungsten, and Low-Carbon Nickel-Chromium-Molybdenum-Copper Alloys Plate, Sheet, and Strip

• ASTM B622: Standard Specification for Seamless Nickel and Nickel Alloy Pipe and Tube

• ASME SB-574/SB-575/SB-622: Equivalent ASME materials standards for pressure vessel applications

3.2 EN/DIN (European/German Standards)

• DIN/EN 2.4819: Material designation for Nickel-Chromium-Molybdenum-Tungsten alloy (UNS N10276)

• DIN 17744: Standard for Nickel-Chromium-Molybdenum alloy bar and wire

• DIN 17750: Standard for Nickel-Chromium-Molybdenum alloy plate, sheet and strip

• DIN 17751: Standard for Nickel-Chromium-Molybdenum alloy seamless tubes

3.3 GB (Chinese National Standards)

• GB/T NS334: Chinese designation equivalent to UNS N10276

• GB/T 15008: Standard for corrosion-resistant alloys

3.4 Other International Standards

• UNS N10276: Unified Numbering System designation

• ISO NiMo16Cr15Fe6W4: International Organization for Standardization designation

These standards ensure that C-276 bars provide consistent performance and interchangeability regardless of manufacturing source when produced to the same specification requirements159.

4 Manufacturing and Heat Treatment

4.1 Hot Rolling Process

Hot rolling of C-276 bars is typically performed in the temperature range of 1200°C to 950°C (2192°F to 1742°F). This process involves:

• Heating the forged or cast billets to the appropriate hot working temperature

• Gradually forming the material to the desired cross-sectional dimensions through a series of rolling passes

• Controlling the cooling rate after rolling to achieve the desired microstructure

• Performing subsequent heat treatments to optimize properties

The hot rolling process must be carefully controlled to avoid incipient melting or excessive oxidation, as the alloy contains elements with relatively low melting point phases that can form if processing temperatures are improperly controlled.

4.2 Solid Solution Heat Treatment

After hot rolling, C-276 bars undergo a solid solution heat treatment typically at temperatures ranging from 1100°C to 1160°C (2012°F to 2120°F), followed by rapid quenching in water9. This process:

• Dissolves any secondary phases that may have formed during thermal processing

• Homogenizes the alloy structure and composition

• Restores the corrosion resistance of the material

• Produces a recrystallized austenitic microstructure with uniform grain size

The rapid quenching (typically water quenching) is essential to prevent precipitation of carbides or intermetallic phases that can occur during slow cooling through the sensitization temperature range (approximately 1000°C to 600°C)9.

4.3 Quality Control and Testing

Hot-rolled C-276 bars are subject to rigorous quality control measures, including:

• Chemical analysis to verify composition conformity

• Tensile testing to confirm mechanical properties

• Hardness testing as an additional quality check

• Non-destructive testing (ultrasonic or eddy current) for detection of internal and surface defects

• Macroetch and microstructural examination to assess grain size and structure

• Corrosion testing when specified (e.g., ASTM G28 Method A for detecting susceptibility to intergranular attack)

5 Applications of C276 Bar

Hastelloy C-276 bars are utilized in numerous industrial applications where exceptional corrosion resistance and reliability are required. The bar form is typically machined into components for use in:

5.1 Chemical Processing Industry

• Reactor vessels and agitator shafts for demanding chemical processes

• Fasteners and valve components for corrosive service

• Pump shafts and impellers for handling aggressive chemicals

• Nozzles and sparger systems for acid distribution

5.2 Pollution Control and Flue Gas Desulfurization (FGD) Systems

• Fan shafts and bearing components in wet scrubber environments

• Agitator shafts for limestone slurries

• Support systems for absorbers and ductwork

• Fasteners and hardware for critical connections

5.3 Pharmaceutical and Food Processing

• Mixing shafts for reaction vessels

• Structural components in high-purity systems

• Fasteners and support elements where contamination must be avoided

5.4 Marine and Offshore Applications

• Shafts for seawater pumps

• Components in seawater valve systems

• Fasteners for critical marine applications

• Bearing surfaces in corrosive marine environments

5.5 Oil and Gas Industry

• Components for sour gas service (high H₂S environments)

• Downhole instrumentation housings

• Valve trim for corrosive service

• Process components in refining applications

The versatility of C-276 bar stock allows for fabrication into countless components where corrosion resistance, mechanical strength, and long-term reliability are essential requirements in aggressive environments78.

6 Other Product Forms of C276 Alloy

While this document focuses on bar products, Hastelloy C-276 is available in multiple product forms to suit various manufacturing and construction needs:

6.1 Wrought Products

• Plate and Sheet: Used for vessel construction, tank lining, and pressure vessel fabrication (ASTM B575)

• Pipe and Tube: Both seamless and welded forms for process piping, heat exchangers, and instrument lines (ASTM B622, B619)

• Wire and Welding Products: Including covered electrodes, bare wire, and cored wire for joining and cladding operations

• Strip and Foil: For specialized applications requiring thin gauge material

6.2 Cast Products

• Investment Castings: For complex components that would be difficult to machine from bar stock

• Sand Castings: For large components and prototypes

• Centrifugal Castings: For cylindrical components such as rings and sleeves

6.3 Special Forms

• Forgings: For high-integrity components requiring optimized grain structure

• Fasteners: Bolts, nuts, washers, and specialized fasteners for corrosive environments

• Expanded Metal: For filtering and screening applications

• Clad Products: Explosion-bonded or roll-bonded clad plate for economical construction of vessels

Each product form is available with appropriate heat treatment and testing to ensure optimal performance in the intended application359.

7 Comparison with Similar Alloys

While C-276 offers an excellent combination of properties, other nickel-based alloys may be selected for specific requirements:

• Hastelloy C-22 (UNS N06022): Enhanced corrosion resistance in oxidizing media and improved thermal stability

• Hastelloy C-2000 (UNS N06200): Superior resistance to oxidizing acids while maintaining reducing acid resistance

• Inconel 625 (UNS N06625): Higher strength at elevated temperatures but less resistance to reducing acids

• Hastelloy B-3 (UNS N10675): Superior resistance to reducing acids, particularly hydrochloric, but less resistant to oxidizing media

The selection of C-276 represents a balanced approach for applications requiring resistance to both oxidizing and reducing environments, particularly where chlorides and other halides are present.

8 Conclusion

Hastelloy C-276 in the form of hot-rolled solid solution treated bar represents a versatile engineering material for demanding corrosive applications. Its exceptional corrosion resistance combined with good mechanical properties and fabricability make it a preferred choice across multiple industries including chemical processing, pollution control, pharmaceuticals, and marine engineering.

The availability of C-276 bar to multiple international standards (ASTM, EN/DIN, GB) ensures material consistency and global availability for critical applications. When properly specified, manufactured, and fabricated, components machined from C-276 bar provide long-term reliability in environments that would rapidly degrade lesser materials.

Engineering designers should consider C-276 bar for applications involving:

• Mixed acid environments containing both oxidizing and reducing species

• Chloride-containing solutions where pitting and crevice corrosion are concerns

• Processes involving wet chlorine gas, hypochlorites, or chlorine dioxide

• High-temperature processes where both corrosion resistance and strength are required

With appropriate attention to fabrication techniques, especially welding and thermal processing, Hastelloy C-276 bar components can provide decades of reliable service in the most challenging industrial environments.