1. Product Overview
Hastelloy C276 is a premium nickel-chromium-molybdenum-tungsten alloy, renowned as a "universal corrosion-resistant material" in the Hastelloy family. Unlike nickel-molybdenum alloys (e.g., Hastelloy B2), it integrates high chromium (for oxidizing media resistance), molybdenum (for reductive media resistance), and tungsten (for enhanced pitting/crevice corrosion resistance) into a low-carbon matrix. This design enables it to withstand both oxidizing and reductive mixed media—such as sulfuric acid-nitric acid blends, chloride-containing solutions, and sour gas environments—while maintaining stable mechanical properties at 20°C-1200°C. It also exhibits excellent weldability and formability, making it indispensable in harsh multi-corrosive scenarios like chemical processing, marine engineering, and environmental protection.
2. Chemical Composition
Hastelloy C276 strictly adheres to international standards (e.g., ASTM B575/B622/B675). Its chemical composition, distinguished by balanced Cr-Mo-W ratios and ultra-low carbon, is shown below:
| Element (Chemical Symbol) | Content Range (Mass Fraction) |
| Ni | ≥57% |
| Cr | 14.5%-16.5% |
| Mo | 15.0%-17.0% |
| W | 3.0%-4.5% |
| Fe | 4.0%-7.0% |
| C | ≤0.01% |
| Si | ≤0.08% |
| P | ≤0.04% |
| S | ≤0.03% |
3. Physical Properties
Hastelloy C276 maintains exceptional stability across a broad temperature range, with physical properties optimized for mixed-corrosion resistance. Key parameters (test conditions per ASTM standards) are listed below:
| Property Item | Value | Test Condition |
| Density | 8.89 g/cm³ | 20°C |
| Melting Range | 1320-1370°C | - |
| Thermal Conductivity | 10.8 W/(m·K) | 20°C |
| Thermal Conductivity | 13.9 W/(m·K) | 500°C |
| Specific Heat Capacity | 427 J/(kg·K) | 20-100°C |
| Coefficient of Linear Expansion | 12.3 ×10⁻⁶/°C | Room Temperature-100°C |
| Coefficient of Linear Expansion | 15.1 ×10⁻⁶/°C | Room Temperature-500°C |
| Electrical Resistivity | 1.38 ×10⁻⁶ Ω·m | 20°C |
| Elastic Modulus | 205 GPa | 20°C |
4. Usage Precautions
Welding Post-Treatment: While Hastelloy C276 has low carbon content, welding may induce precipitation of brittle intermetallic phases (e.g., σ-phase). Post-weld solution heat treatment (1120-1150°C, rapid quenching) is recommended to restore corrosion resistance and toughness.
Avoid Extreme High-Temperature Oxidation: Long-term service above 1200°C may cause surface oxide spallation. For temperatures exceeding this range, use protective coatings (e.g., alumina-based coatings) or select high-temperature-resistant alloys.
Storage & Cleaning: Store in a dry, chloride-free environment to prevent pitting from chloride-containing moisture. Clean surface contaminants (e.g., oil, grease) with alcohol or acetone before use—avoid chlorinated solvents that may damage the alloy.
Crevice Corrosion Prevention: In chloride-rich environments (e.g., seawater), minimize crevices in joint designs (use welds instead of bolts where possible) and apply anti-crevice sealants (e.g., PTFE gaskets).
5. Selection Recommendations
Mixed Corrosion Scenarios: Prioritize Hastelloy C276 for systems involving both oxidizing (e.g., NO₃⁻, O₂) and reductive (e.g., H₂S, organic acids) media—scenarios where Hastelloy B2 (poor oxidizing resistance) or 316L (poor chloride resistance) fail.
Chloride-Containing Environments: For seawater, brine, or chloride solvent systems, select C276 plates/pipes to resist pitting and stress corrosion cracking (SCC).
High-Purity Requirements: In pharmaceutical or food processing, C276 is ideal due to its low impurity content and minimal metal ion leaching—choose cold-rolled finishes for smoother surfaces (reducing microbial adhesion).
Cost-Benefit Balance: For simple reductive acid scenarios (e.g., pure hydrochloric acid ≤100°C), Hastelloy B2 may be more cost-effective. Reserve C276 for complex, multi-corrosive 工况 to optimize budget.
