Alloy 20 (UNS N08020) is a nickel-iron-chromium-based alloy stabilized with niobium and enhanced with copper and molybdenum. It is specifically formulated to provide exceptional resistance to sulfuric acid, phosphoric acid, and a wide range of organic acids commonly encountered in chemical processing environments.

1. Product Specifications & Availability

Alloy 20 is available in multiple forms for chemical processing and related industries.

• Forms: Bars, Rods, Forgings (Rings/Flanges), Sheet, Plate, Strip, Coil, Welding Wire, Spring Wire, Seamless Tube, Welded Pipe.

• Certifications: ISO 9001 and AS9120 certified supplier.

• Support: Stock lists, free samples, and competitive quotes available upon request.

Chemical Composition

Physical & Mechanical Properties

2. Operating Conditions & Selection Criteria

Alloy 20 is selected specifically for resistance to reducing acids and aggressive chemical environments.

• Corrosion Resistance: Exceptional resistance to sulfuric acid in various concentrations and temperatures. Also resists phosphoric acid, nitric acid, and organic acids. The copper and molybdenum additions provide protection against reducing media while chromium offers resistance to oxidizing conditions.

• Temperature Range: Maintains mechanical properties and corrosion resistance up to approximately 500°C (932°F). Suitable for elevated temperature chemical processing applications.

• Primary Function: Designed for handling aggressive acids and chemical streams. Not intended for extreme high-temperature service beyond 500°C.

• Stabilization: Niobium addition prevents intergranular corrosion after welding by stabilizing carbides, eliminating the need for post-weld heat treatment in most service conditions.

3. Fabrication Guidelines & Material Comparison

Alloy 20 offers good fabricability with standard techniques while maintaining corrosion resistance in the welded condition.

Fabrication Guidelines:

• Welding: Good weldability using common techniques: shielded metal arc (SMAW), gas tungsten arc (GTAW/TIG), and gas metal arc (GMAW/MIG). For optimal corrosion resistance in the weld zone, use Inconel family filler metals as standard practice.

• Hot Working: Can be hot worked within 760°C to 1175°C (1400°F to 2150°F). Adhere to recommended temperature range to ensure material integrity.

• Annealing: Perform at 982°C to 1010°C (1800°F to 1850°F). Holding time depends on cross-sectional thickness. Follow with rapid cooling (air or water quench) to achieve optimal corrosion resistance and uniform microstructure.

• Cold Working: Can be cold formed using standard methods.

Material Comparison:

• vs. Stainless Steel 316: Alloy 20 offers significantly better resistance to sulfuric acid compared to 316 stainless steel, which corrodes rapidly in even moderate concentrations of sulfuric acid. Alloy 20 is the standard upgrade for sulfuric acid service.

• vs. Hastelloy C-276: Alloy 20 provides a cost-effective solution for sulfuric and phosphoric acid applications where the extreme universal corrosion resistance of C-276 is not required.

• vs. Monel 400: Monel 400 excels in hydrofluoric acid and seawater but has limited resistance to oxidizing acids. Alloy 20 is preferred for mixed acid streams containing sulfuric or nitric components.

Primary Applications:

• Chemical processing equipment: mixing tanks, heat exchangers, reactors

• Valves, fittings, and fasteners for acid service

• Piping systems for sulfuric and phosphoric acid handling

• Pharmaceutical processing equipment requiring purity and corrosion resistance

• Food processing equipment exposed to acidic media

• Gasoline, solvent, and explosives production facilities

• Pickling equipment and acid recovery systems

Contact & Support

For detailed specifications, availability, and application guidance for Alloy 20, contact ZYTC Alloy. Our technical team provides material certification and engineering support for chemical processing and acid-handling applications.

Contact Us:

Email:daisy@zytcsteel.com

WhatsApp/WeChat: +86 17335753350