Hastelloy® G-35 alloy is a nickel-chromium-molybdenum superalloy specifically formulated to handle the most aggressive chemical environments, particularly in the fertilizer production industry. Its superior performance sets a new benchmark for durability in applications where other metallic materials rapidly fail.

1. Product Specifications & Properties

Alloy G-35 is a nickel-chromium-molybdenum alloy with high chromium content, designed to provide superior corrosion resistance in highly oxidizing media while maintaining good resistance in reducing environments. Its balanced chemistry addresses the limitations of earlier alloys in phosphoric acid evaporator service.

Chemical Composition (%, nominal)

Mechanical & Physical Properties

2. Operating Conditions & Selection Guidelines

• Ideal Media: Specifically engineered for"fertilizer-grade"phosphoric acid (P₂O₅) containing impurities such as chlorides, fluorides, and sulfuric acid residues. Excellent resistance to nitric acid and mixed acids containing nitric due to high chromium content. Good resistance to reducing acids from molybdenum content

• Critical Advantage: Superior resistance to localized pitting and crevice corrosion beneath deposits in phosphoric acid evaporators—a common failure point for other alloys. Much less susceptible to chloride-induced stress corrosion cracking than stainless steels and nickel-chromium-iron alloys. Unlike other Ni-Cr-Mo alloys, highly resistant to caustic de-alloying in hot sodium hydroxide

• Temperature Range: Effective at elevated temperatures typical of phosphoric acid concentration processes (evaporator service). Maintains creep strength up to 700°C

• Common Applications: P₂O₅ evaporator tubes, phosphoric acid production equipment, nitric acid handling systems, chemical reactors, heat exchangers, pressure vessels, piping systems, and components exposed to oxidizing acids, chlorides, and caustic environments

3. Fabrication & Material Comparison

• Welding Considerations: Weldability similar to C-276 alloy. GTAW/TIG preferred for plate and root welding; GMAW suitable for plate welding; SMAW with coated electrodes advantageous for field welding. Submerged arc welding not recommended due to high heat input. Interpass temperature should be maintained at 93°C (200°F) max to minimize second-phase precipitation. Welding of cold-worked material discouraged without prior solution annealing

• Heat Treatment: Solution annealing at 1177°C (2150°F) followed by rapid water quench restores optimal corrosion resistance after hot working

• Forming & Machining: Good formability using conventional methods. Compatible with standard machining techniques for nickel-based alloys

• Versus G-30: Significantly improved resistance in"fertilizer-grade"phosphoric acid environments. Far superior to G-30 and stainless steels in this specific service . Higher chromium content (33% vs. 28-30%) provides enhanced oxidizing acid resistance

• Versus C-276: G-35 specifically outperforms C-276 in phosphoric acid and highly oxidizing environments where C-276 may show limitations. C-276 remains preferred for broad-spectrum reducing/oxidizing balance

• Versus Stainless Steels: Dramatically superior resistance to phosphoric acid, nitric acid, and chloride-containing environments where 316L and 317L fail rapidly

4. Product Availability

• Plate, Sheet, and Strip
• Bar, Billet, and Wire
• Pipe and Tube
• Covered Welding Electrodes

Contact ZYTC Alloy for application engineering support or to request a quotation. Our technical team can assist with material selection based on your specific process conditions. ISO 9001 and AS9120 certified supplier.

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Email:daisy@zytcsteel.com

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