Hastelloy Alloy C-276 represents the pinnacle of nickel-molybdenum-chromium superalloy technology, delivering unmatched corrosion resistance in the most aggressive chemical processing environments known to industry. We at MWalloys recognize this exceptional material as the definitive solution for applications involving wet chlorine gas, hypochlorites, chlorine dioxide, and mixed acid environments where conventional alloys suffer catastrophic failure. With its unique combination of 16% molybdenum, 15.5% chromium, and 57% nickel, C-276 provides extraordinary resistance to both oxidizing and reducing acids, making it indispensable for chemical processing, pollution control, and pulp & paper industries. The alloy's remarkable versatility extends from cryogenic temperatures to 1000°C, while maintaining excellent fabricability and weldability characteristics that enable complex component manufacturing for critical industrial applications worldwide.
What is Hastelloy Alloy C-276?
Hastelloy Alloy C-276 stands as one of the most versatile and corrosion-resistant nickel-based superalloys ever developed, specifically engineered to withstand the harshest chemical processing environments. We classify this material as a solid-solution strengthened alloy that derives its exceptional performance from a carefully balanced combination of nickel, molybdenum, and chromium.
The alloy's development originated in the 1960s to address the chemical industry's need for materials capable of handling mixed acid environments and chlorinated compounds. Traditional stainless steels and even earlier superalloys proved inadequate for these aggressive conditions, leading to frequent equipment failures and safety concerns.
C-276's metallurgical structure consists of a stable austenitic matrix that remains unchanged across a wide temperature range. This microstructural stability prevents the formation of brittle phases that could compromise mechanical properties or corrosion resistance during service. We observe that this characteristic makes C-276 particularly suitable for applications involving thermal cycling.
The alloy's low carbon content minimizes carbide precipitation, which could create galvanic cells and compromise corrosion resistance. This design philosophy ensures consistent performance throughout the material's cross-section, eliminating weak points that might develop during welding or high-temperature exposure.
What is The Chemical Composition Of Hastelloy Alloy C-276?
The chemical composition of Hastelloy Alloy C-276 is precisely engineered to provide optimal corrosion resistance across the broadest possible range of chemical environments. Understanding these elemental contributions enables engineers to predict material behavior and select appropriate applications.
| Element | Weight Percentage (%) | Primary Function |
|---|---|---|
| Nickel (Ni) | 54.0 - 59.0 | Base metal providing corrosion resistance |
| Molybdenum (Mo) | 15.0 - 17.0 | Resistance to reducing acids and crevice corrosion |
| Chromium (Cr) | 14.5 - 16.5 | Oxidizing acid resistance and passivation |
| Iron (Fe) | 4.0 - 7.0 | Cost reduction and strength enhancement |
| Tungsten (W) | 3.0 - 4.5 | Additional resistance to reducing conditions |
| Cobalt (Co) | 2.5 max | Strength improvement |
| Carbon (C) | 0.010 max | Minimized to prevent carbide formation |
| Manganese (Mn) | 1.0 max | Deoxidizer and hot working improvement |
| Silicon (Si) | 0.08 max | Deoxidizer, controlled to prevent precipitation |
| Phosphorus (P) | 0.040 max | Controlled to prevent grain boundary embrittlement |
| Sulfur (S) | 0.030 max | Minimized for improved ductility |
| Vanadium (V) | 0.35 max | Grain refinement |
The synergistic effect of molybdenum and tungsten provides C-276 with exceptional resistance to reducing acids such as hydrochloric and sulfuric acid. We emphasize that the chromium content ensures excellent performance in oxidizing environments, while the nickel matrix maintains structural integrity across temperature extremes.
The extremely low carbon content distinguishes C-276 from many other superalloys, preventing the formation of chromium carbides that could deplete the matrix of corrosion-resistant elements. This compositional control ensures uniform corrosion resistance throughout welded structures and heat-affected zones.
What are Hastelloy Alloy C-276 Mechanical Properties?
The mechanical properties of Hastelloy Alloy C-276 demonstrate exceptional performance retention across a wide temperature range, from cryogenic conditions to high-temperature service. These properties enable the alloy to function effectively in both structural and pressure-containing applications.
| Property | Room Temperature | 650°C | 800°C | Test Standard |
|---|---|---|---|---|
| Tensile Strength (MPa) | 690-900 | 450-600 | 310-450 | ASTM E8 |
| Yield Strength (MPa) | 280-380 | 200-280 | 140-200 | ASTM E8 |
| Elongation (%) | 40-60 | 35-50 | 30-45 | ASTM E8 |
| Reduction of Area (%) | 65-80 | 60-75 | 55-70 | ASTM E8 |
| Hardness (HRB) | 87-95 | - | - | ASTM E18 |
| Impact Strength (J) | 325-400 | 280-350 | 220-300 | ASTM E23 |
| Modulus of Elasticity (GPa) | 205 | 180 | 160 | ASTM E111 |
| Poisson's Ratio | 0.31 | 0.32 | 0.33 | ASTM E132 |
These mechanical properties reflect C-276's excellent combination of strength and ductility, essential for fabrication and service performance. We note that the alloy maintains significant impact toughness even at elevated temperatures, preventing brittle failure under dynamic loading conditions.
The high elongation values indicate excellent formability, enabling complex component fabrication through conventional metalworking processes. This characteristic proves particularly valuable for chemical processing equipment requiring intricate geometries and tight dimensional tolerances.
What is the Specification of Hastelloy Alloy C-276?
Hastelloy Alloy C-276 specifications encompass various international standards that govern chemical composition, mechanical properties, and quality requirements. These specifications ensure consistent material performance across different suppliers and geographic markets.
| Specification Category | Details | Standard Reference |
|---|---|---|
| ASTM Designation | B575, B619, B622, B626 | Various product forms |
| UNS Number | N10276 | Unified Numbering System |
| AMS Specifications | 5750, 5887, 5888 | Aerospace applications |
| ASME Code Case | N-06276 | Pressure vessel construction |
| Product Forms | Plate, sheet, bar, pipe, tube, fittings | Multiple ASTM standards |
| Size Range | 0.5mm - 300mm thickness | Product dependent |
| Heat Treatment | Solution annealed | 1040-1150°C |
| Surface Condition | Annealed, pickled, polished | ASTM A480 |
| Dimensional Tolerance | ±0.05mm to ±5.0mm | Size and form dependent |
| Chemical Composition | Per ASTM B575 | Ladle and check analysis |
| Mechanical Properties | Room temperature minimum | ASTM E8, E21 |
| Corrosion Testing | Various media specific | ASTM G28, G48 |
The comprehensive specification framework ensures that C-276 meets rigorous quality requirements for critical applications. We maintain strict adherence to these standards throughout our manufacturing and quality control processes, ensuring consistent material performance.
International harmonization of specifications facilitates global procurement and ensures material interchangeability between suppliers. The unified numbering system (UNS N10276) provides universal identification for engineering and procurement purposes.
What Does Hastelloy Alloy C-276 Stand For?
Hastelloy Alloy C-276 derives its designation from the Hastelloy trademark combined with a specific alloy identification system. The "C" designation indicates the alloy belongs to the chromium-containing family of Hastelloy alloys, while "276" represents the specific compositional variant within this family.
The Hastelloy trademark, originally developed by Haynes International, represents a family of nickel-based superalloys designed for extreme service conditions. The naming convention helps engineers and procurement professionals identify specific alloy compositions and their intended performance characteristics.
We recognize that the "C-276" designation has become synonymous with premium corrosion resistance in chemical processing applications. The number "276" reflects the alloy's development chronology and compositional optimization for broad-spectrum chemical resistance.
This designation system provides clear identification for material specifications, heat treatment requirements, and quality control procedures. The standardized nomenclature ensures accurate communication throughout the global supply chain and facilitates proper material selection for specific applications.
What is the Density of Hastelloy Alloy C-276?
The density of Hastelloy Alloy C-276 is 8.89 g/cm³ at room temperature, making it approximately 14% heavier than stainless steel but lighter than many tungsten-containing superalloys. This density value is essential for structural calculations, equipment design, and cost estimation in engineering applications.
Temperature variations affect C-276's density through thermal expansion, with the density decreasing to approximately 8.75 g/cm³ at 650°C and 8.65 g/cm³ at 800°C. We incorporate these temperature-dependent values into high-temperature design calculations and thermal stress analyses.
The relatively high density of C-276 reflects its significant molybdenum and tungsten content, both dense refractory elements that contribute to the alloy's exceptional corrosion resistance. This density-performance relationship represents an acceptable trade-off for applications where corrosion resistance is paramount.
Compared to aluminum alloys with densities around 2.7 g/cm³, C-276 is significantly heavier but offers vastly superior chemical resistance and high-temperature performance. The density consideration becomes particularly important in rotating equipment and weight-sensitive applications.
What is the Difference Between Hastelloy Alloy C-276, G-30 and X?
The differences between Hastelloy Alloys C-276, G-30, and X reflect their distinct compositional designs and optimized performance characteristics for specific industrial applications. Understanding these differences enables engineers to select the most appropriate alloy for their service requirements.
Hastelloy Alloy C-276 contains high molybdenum (16%) and moderate chromium (15.5%) content, providing exceptional resistance to reducing acids and mixed oxidizing/reducing environments. Its low carbon content prevents carbide precipitation, ensuring consistent corrosion resistance throughout welded structures.
Hastelloy G-30 features higher chromium content (30%) combined with molybdenum (5.5%) and tungsten (2.5%), optimizing it for mixed acid environments and oxidizing conditions. The higher chromium content provides superior resistance to nitric acid and other oxidizing media where C-276 might show limitations.
Hastelloy X contains chromium (22%) and moderate amounts of molybdenum (9%) with iron (18%), designed primarily for high-temperature structural applications rather than maximum corrosion resistance. We recommend Hastelloy X for gas turbine components and aerospace applications requiring strength at elevated temperatures.
Corrosion resistance patterns vary significantly between these alloys. C-276 excels in hydrochloric acid and reducing environments, G-30 performs better in mixed acids and oxidizing conditions, while Hastelloy X focuses on high-temperature oxidation resistance rather than chemical corrosion.
What is a Hastelloy Alloy C-276 Used For?
Hastelloy Alloy C-276 finds extensive application in chemical processing industries where aggressive corrosive environments exceed the capabilities of conventional materials. The alloy's broad-spectrum corrosion resistance makes it indispensable for handling multiple chemicals within single processing facilities.
Chemical processing equipment represents the largest application segment, including reactors, heat exchangers, distillation columns, and piping systems handling hydrochloric acid, sulfuric acid, and chlorinated compounds. We observe exceptional performance in applications involving wet chlorine gas, where other materials suffer rapid degradation.
Pollution control systems utilize C-276 for flue gas desulfurization equipment, where the combination of high temperatures, moisture, and corrosive gases creates extremely challenging conditions. The alloy's resistance to chloride-induced stress corrosion cracking proves essential in these applications.
Pharmaceutical and fine chemical manufacturing employs C-276 for reactor vessels and processing equipment where product purity requirements demand materials that resist contamination and maintain surface integrity. The alloy's cleanability and resistance to crevice corrosion support stringent hygiene standards.
Pulp and paper industry applications include bleaching equipment, digesters, and recovery systems where chlorinated compounds and sulfur-containing chemicals create aggressive environments. C-276's performance in these applications significantly extends equipment life and reduces maintenance requirements.
What is Hastelloy Alloy C-276 Classification?
Hastelloy Alloy C-276 is classified as a nickel-molybdenum-chromium superalloy according to international metallurgical standards. The Unified Numbering System designates it as UNS N10276, providing universal identification across different national standards and specifications.
According to ASTM classification systems, C-276 falls under the category of nickel-chromium-molybdenum-tungsten alloys designed for corrosive service applications. Multiple ASTM specifications cover various product forms, including B575 for plate, B619 for welded pipe, and B622 for seamless pipe and tube.
European standards classify C-276 under EN 2.4819, ensuring material consistency and interchangeability between American and European suppliers. This harmonized classification system facilitates international trade and maintains identical performance standards across global markets.
The classification distinguishes C-276 from other superalloys based on its specific composition ranges, mechanical properties, and corrosion resistance characteristics. We utilize these classifications for material selection, quality control, and certification procedures throughout our operations.
What is C276 Material Equivalent To?
C-276 material equivalents exist from various international suppliers, though direct substitution requires careful evaluation of specific composition and performance characteristics. Understanding these equivalents helps engineers maintain supply security and cost optimization.
International equivalents include Inconel 686 from Special Metals Corporation, which offers similar corrosion resistance with slightly different composition. Cronifer 1925 hMo from VDM Metals provides comparable performance in many applications, though specific corrosion testing may be required for critical uses.
European designations such as NiMo16Cr15W (EN 2.4819) and German standard 2.4819 provide equivalent specifications for European markets. Japanese equivalent JIS NW6276 ensures consistency in Asian manufacturing and supply chains.
We emphasize that while these materials share similar composition ranges, subtle differences in manufacturing processes, heat treatment, and quality control procedures may affect performance in specific applications. Comprehensive qualification testing is recommended when substituting equivalent materials in critical services.
Is Hastelloy Alloy the Strongest Metal?
While Hastelloy alloys rank among the strongest materials for specific service conditions, they are not universally the strongest metals across all applications. The concept of "strongest" depends on the specific properties being evaluated and the operating environment.
C-276 demonstrates exceptional strength in corrosive environments where other materials lose their structural integrity through chemical attack. The alloy maintains useful mechanical properties in chemical media that would rapidly degrade conventional steels or aluminum alloys.
Room temperature strength comparison shows that some precipitation-hardened superalloys and tool steels achieve higher ultimate tensile strengths than C-276. However, these materials typically cannot maintain their properties in the aggressive chemical environments where C-276 excels.
We emphasize that Hastelloy's true strength lies in its ability to combine good mechanical properties with exceptional corrosion resistance and thermal stability. This multifaceted performance makes Hastelloy stronger in the context of overall capability rather than single-property optimization.
Global Market Prices 2025 Comparison
The global market for Hastelloy Alloy C-276 reflects the specialized nature of this superalloy and the concentrated supplier base worldwide. Pricing variations depend on product form, specifications, quantity, and regional market dynamics.
| Region | Price Range (USD/kg) | Market Factors | Supply Status |
|---|---|---|---|
| North America | $55-75 | Strong chemical industry demand | Good availability |
| Europe | $58-78 | Environmental regulations driving demand | Stable supply |
| Asia-Pacific | $52-68 | Manufacturing expansion, cost competition | Excellent |
| Middle East | $60-80 | Petrochemical projects, import costs | Moderate |
| South America | $62-82 | Limited suppliers, logistics challenges | Variable |
| Africa | $65-85 | Import dependencies, project demand | Limited |
Price fluctuations occur primarily due to raw material costs, particularly nickel and molybdenum, which represent significant portions of the alloy's value. We recommend establishing strategic supply partnerships for major projects to minimize price volatility and ensure material availability.
The specialized processing requirements and limited global supplier base contribute to premium pricing compared to conventional stainless steels. However, the superior corrosion resistance and extended service life typically justify the investment in critical chemical processing applications.
Can Hastelloy Alloy C-276 be Welded?
Hastelloy Alloy C-276 exhibits excellent weldability using conventional fusion welding processes, making it suitable for complex fabrication and field maintenance operations. The alloy's composition and metallurgical characteristics facilitate welding without requiring extensive preheating or complex post-weld treatments.
Gas tungsten arc welding (GTAW) represents the preferred method for C-276, providing precise control over heat input and producing high-quality welds with excellent corrosion resistance. We recommend using matching composition filler metals (ERNiMo-3) to maintain chemical compatibility and performance characteristics.
Preheating requirements for C-276 are minimal, typically limited to removing moisture and surface contaminants. The alloy's low carbon content and stable austenitic structure prevent the formation of brittle phases that could compromise weld integrity or require complex thermal treatments.
Post-weld heat treatment is generally not required for C-276 weldments, though solution annealing may be beneficial for applications involving maximum corrosion resistance or stress relief. The alloy's solid-solution strengthening mechanism prevents age-hardening effects that could complicate processing.
Welding procedure considerations include maintaining low heat input to preserve corrosion resistance, using proper shielding gas compositions (typically argon), and controlling cleanliness to prevent contamination that could affect chemical resistance.
Advantages of Hastelloy Alloy C-276
The advantages of Hastelloy Alloy C-276 stem from its unique metallurgical design and exceptional performance characteristics in aggressive chemical environments. These benefits make it the preferred choice for critical applications where material failure could have severe consequences.
Outstanding corrosion resistance across the broadest spectrum of chemical environments represents the primary advantage, with exceptional performance in both oxidizing and reducing acids. The alloy handles mixed acid conditions where other materials experience selective attack or general corrosion.
Excellent fabricability despite its high-performance characteristics enables complex component manufacturing using conventional metalworking techniques. We observe that C-276 can be formed, machined, and welded without extraordinary precautions, facilitating cost-effective fabrication.
Superior thermal stability prevents metallurgical degradation during thermal cycling and high-temperature exposure. The stable austenitic structure resists phase transformations that could compromise mechanical properties or corrosion resistance.
Broad temperature capability from cryogenic conditions to 1000°C makes C-276 suitable for diverse applications within a single facility. This versatility reduces inventory requirements and simplifies material selection for complex processing systems.
Manufacturing Process of Hastelloy Alloy C-276
The manufacturing process of Hastelloy Alloy C-276 begins with vacuum induction melting (VIM) to achieve precise chemical composition control and eliminate impurities that could compromise corrosion resistance. This primary melting process ensures homogeneous distribution of alloying elements throughout the ingot.
Secondary refining through vacuum arc remelting (VAR) or electroslag remelting (ESR) further improves metallurgical quality by eliminating inclusions and reducing segregation. We carefully control cooling rates during solidification to prevent the formation of undesirable phases.
Hot working operations including forging, rolling, or extrusion are performed at carefully controlled temperatures to optimize grain structure and mechanical properties. The working temperature range typically spans 1000-1200°C, depending on the specific product form and dimensional requirements.
Solution heat treatment follows hot working, typically performed at temperatures between 1040-1150°C to dissolve any precipitates and establish the desired austenitic microstructure. Rapid cooling, usually by water quenching, preserves the single-phase structure essential for maximum corrosion resistance.
Cold working operations, when required, are performed after solution treatment to achieve specific dimensional tolerances or mechanical properties. The degree of cold work is carefully controlled to prevent excessive work hardening that could compromise subsequent processing.
Quality control throughout manufacturing includes comprehensive chemical analysis, mechanical testing, corrosion testing, and non-destructive examination. Each processing step is monitored to ensure compliance with specifications and maintain full traceability for critical applications.
Spanish Chemical Complex Procurement Case Study
A major chemical processing facility in Barcelona, Spain, successfully implemented Hastelloy Alloy C-276 components throughout their chlor-alkali production facility to address severe corrosion challenges in wet chlorine service. This project demonstrates the material's effectiveness in one of the most demanding chemical processing environments.
The facility experienced recurring failures of conventional stainless steel equipment when handling wet chlorine gas, hypochlorite solutions, and chlorine dioxide. These failures resulted in unplanned shutdowns, safety concerns, and significant maintenance costs that threatened the facility's economic viability.
MWalloys supplied 18 tons of C-276 in various forms including heat exchanger tubing, reactor internals, piping systems, and valve components. The procurement process involved detailed material qualification testing and coordination with European certification requirements for pressure equipment.
Installation was completed during a scheduled turnaround, with specialized welding procedures qualified according to European standards EN 288 and ASME Section IX. Local fabrication contractors received comprehensive training on C-276 welding techniques and quality control procedures.
Performance monitoring over 42 months revealed exceptional results, with C-276 components showing virtually no corrosion in the aggressive chlorine environment. Equipment availability improved by 35%, and maintenance costs decreased by over 60% compared to previous materials.
The success led to plant-wide adoption of C-276 for all chlorine-handling equipment, including expansion to related caustic service applications. The facility now serves as a reference site for other European chemical producers considering material upgrades.
Economic benefits totaled €3.8 million over three years when considering reduced maintenance, improved availability, and enhanced safety performance. The project established C-276 as the standard material for chlor-alkali applications throughout the company's European operations.
Frequently Asked Questions
Q1: What is the maximum temperature for continuous service with Hastelloy C-276?
Hastelloy C-276 can operate continuously at temperatures up to 650°C in most chemical environments, with intermittent service capability extending to 1000°C depending on specific conditions. The actual temperature limit depends on the chemical environment, stress levels, and required service life. We recommend detailed evaluation for applications exceeding 600°C to ensure optimal performance.
Q2: How does C-276 compare to Inconel 625 for chemical processing applications?
C-276 offers superior resistance to reducing acids and chloride environments due to its higher molybdenum content, while Inconel 625 provides better high-temperature strength and oxidation resistance. The choice depends on specific chemical exposures and operating conditions. We provide comparative corrosion data to help engineers select the optimal material.
Q3: Can C-276 be used in contact with food and pharmaceutical products?
C-276 meets FDA requirements for food contact applications and USP Class VI standards for pharmaceutical use when properly processed and finished. The alloy's corrosion resistance and cleanability make it suitable for sterile processing equipment. We recommend verification testing for specific product contact applications.
Q4: What surface treatments are available for C-276 to enhance performance?
Standard surface treatments include pickling, passivation, and electropolishing to optimize corrosion resistance and cleanability. Specialized coatings are generally not required due to C-276's inherent chemical resistance. Surface roughness specifications can be tailored to specific application requirements.
Q5: Is C-276 suitable for hydrogen service applications?
C-276 exhibits good resistance to hydrogen embrittlement and can be used in hydrogen-containing environments at moderate temperatures and pressures. However, specific evaluation is required for high-pressure hydrogen service or applications involving hydrogen sulfide. We provide detailed guidance for hydrogen service applications.
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