What are the composition and characteristics of HASTELLOY C-276?

HASTELLOY C-276 is a nickel-molybdenum-chromium superalloy known for its exceptional corrosion resistance and high-temperature strength. Here are the composition and characteristics of HASTELLOY C-276:

Composition:

• Nickel (Ni): Approximately 57%
• Chromium (Cr): Approximately 16-17%
• Molybdenum (Mo): Approximately 15-17%
• Iron (Fe): Approximately 5%
• Tungsten (W): Approximately 3-4%
• Cobalt (Co): Maximum of 2.5%
• Manganese (Mn): Maximum of 1%
• Carbon (C): Maximum of 0.01%
• Silicon (Si): Maximum of 0.08%
• Sulfur (S): Maximum of 0.03%
• Phosphorus (P): Maximum of 0.04%

Characteristics:

1. Corrosion Resistance: HASTELLOY C-276 exhibits outstanding resistance to a wide range of corrosive environments, including oxidizing and reducing acids, pitting and crevice corrosion, chlorides, and seawater. It is highly resistant to stress corrosion cracking (SCC) and corrosion by sulfuric, hydrochloric, and phosphoric acids.

2. High-Temperature Strength: The alloy retains its mechanical strength and integrity at elevated temperatures, making it suitable for use in high-temperature applications such as chemical processing, pollution control, and petrochemical refining. It has excellent creep and rupture strength at temperatures up to 1,200°C (2,192°F).

3. Excellent Fabricability: HASTELLOY C-276 can be easily fabricated using conventional methods such as welding, machining, forming, and forging. It exhibits good weldability and can be welded using various techniques, including gas tungsten arc welding (GTAW), gas metal arc welding (GMAW), and shielded metal arc welding (SMAW).

4. Versatility: The alloy is versatile and finds applications in a wide range of industries, including chemical processing, aerospace, pharmaceuticals, pulp and paper, and pollution control. It is used in equipment such as reactors, heat exchangers, valves, pumps, and piping systems where corrosion resistance and high-temperature performance are critical.

5. Resistance to Metal Dusting: HASTELLOY C-276 is resistant to metal dusting, a form of corrosion that occurs in high-temperature environments containing carbonaceous gases. This makes it suitable for use in environments where metal dusting corrosion is a concern, such as petrochemical and refinery applications.

6. Low Thermal Expansion: The alloy has a low coefficient of thermal expansion, which minimizes the risk of thermal stress and distortion in high-temperature applications. This property allows for dimensional stability and reliable performance over a wide range of temperatures.

Overall, HASTELLOY C-276 is a highly versatile and corrosion-resistant alloy with excellent mechanical properties and fabricability, making it a preferred choice for demanding applications in aggressive environments where reliability, performance, and longevity are paramount.