Chemical Composition Of Hastelloy

Hastelloy is a nickel-based corrosion-resistant alloy. Its chemical composition varies depending on the specific grade, but it mainly includes the following elements and their functions: ‌

1. Main elements and functions
‌Nickel (Ni): It usually accounts for more than 50% (such as C-276 contains about 56% nickel, C-22 contains 56-61%), which is the matrix element of the alloy, providing basic corrosion resistance and high-temperature stability, especially in reducing media.
‌Chromium (Cr): The content is 14.5-22.5% (such as C-22 contains 20-22.5%), forming a dense oxide film to enhance oxidation resistance, especially in high temperature or chlorine-containing environments.
‌Molybdenum (Mo): 12.5-17% (such as C-276 contains 16%), significantly improving the ability to resist pitting and crevice corrosion, and has outstanding effects on reducing media such as hydrochloric acid and sulfuric acid.
‌Tungsten (W): 2.5-4.5% (such as C-22 contains 2.5-3.5%), synergistically with molybdenum to enhance high temperature corrosion resistance, especially in acidic environments.
2. Minor elements and their effects
‌Iron (Fe): The content is usually ≤20% (such as C-276 contains 5%), used to optimize mechanical properties and reduce costs.
‌Cobalt (Co): ≤2.5%, improve heat resistance and hardness.
‌Silicon (Si), manganese (Mn), carbon (C): extremely low content (such as C≤0.015%), avoid intergranular corrosion and maintain ductility.
3. Typical composition differences of different series of Hastelloy alloys
‌B series (such as B-2): mainly Ni-Mo, almost no chromium, designed for strong reducing environments (such as hydrochloric acid).
‌C series (such as C-276, C-22): Ni-Cr-Mo system, taking into account both oxidation and reduction media corrosion resistance, suitable for chemical and petroleum fields.
‌G series: High chromium (about 22%) iron, for strong oxidizing media (such as phosphoric acid).
‌Summary: The chemical composition of Hastelloy achieves multi-element synergistic effect through precise proportioning, enabling it to maintain excellent performance in extreme corrosive environments. In specific applications, it is necessary to select the appropriate grade according to the characteristics of the medium (such as oxidation/reduction, temperature).