Hastelloy C276

Hastelloy C276 (UNS N10276) is a nickel-molybdenum-chromium-tungsten quaternary superalloy, whose excellence stems from precise element ratios and microstructure control: Nickel (Ni) 57–60 - The base element that provides excellent toughness and resistance to chloride stress corrosion cracking (SCC) Molybdenum (Mo) 15–17 - Resists corrosive action of reducing acids (hydrochloric acid, sulfuric acid, phosphoric acid), inhibits pitting and crevice corrosion Chromium (Cr) 14.5–16.5 - Resists corrosive action of oxidizing media (nitric acid, hypochlorite, chlorine dioxide), forms a dense Cr₂O₃ passivation film Tungsten (W) 3–4.5 - Further strengthens the resistance to local corrosion and enhances high-temperature strength Iron (Fe) ≤7 - Optimizes cost and machinability, without affecting corrosion resistance Carbon (C) ≤0.01 - Extremely low content, completely eliminating welding sensitization and intergranular corrosion risks The corrosion resistance mechanism involves multi-layered collaborative protection: Surface passivation film: Forms a double-layer oxide film of Cr₂O₃/NiCr₂O₄ in an oxidizing environment, preventing the penetration of the medium; The "self-repair" effect of molybdenum: In reducing acids, MoO₂ is generated and fills in local defects, preventing the expansion of pitting; Low-carbon solution state: After solution treatment at 1050–1100°C, carbides are completely dissolved, avoiding chromium deficiency at the grain boundaries and achieving zero intergranular corrosion.