Among the high-performance nickel alloys, Hastelloy C2000 has exceptionally balanced resistance to a wide spectrum of corrosive media. As a supplier of precision-forged Hastelloy fittings, we provide this objective overview of its chemical compatibility.
Resistance to Specific Acids
Hastelloy C2000 exhibits exceptional resistance to a variety of acids, particularly in reducing and oxidizing conditions.
Sulfuric Acid: The alloy shows enhanced performance due to its copper content, with corrosion rates below 0.1 mm/year in concentrations up to 80% at temperatures reaching 66°C. It outperforms alloys like C-276 and 625 in iso-corrosion tests for this acid.
Hydrochloric Acid: It maintains low corrosion rates (less than 0.01 mm/year) in dilutions up to 5% at 52°C, and remains viable up to 10% concentration, surpassing other Ni-Cr-Mo alloys in this range.
Hydrofluoric Acid: External corrosion rates are minimal (0.01-0.03 mm/year) at 1% concentration up to 38°C, though internal attack may occur in higher exposures.
Other Acids: In phosphoric acid, rates are below 0.01 mm/year at 50-80% concentrations up to 93°C. Nitric acid resistance yields rates of 0.02 mm/year in 20% boiling solutions. Organic acids like acetic and formic show negligible corrosion.
Hastelloy C2000 Chemical Compatibility Profile
Sulfuric Acid
Hastelloy C2000 exhibits outstanding resistance to sulfuric acid across a wide range of temperatures and concentrations. In many applications, it outperforms C276, particularly in dilute to mid-range concentrations where reducing conditions are prevalent.
Hydrochloric Acid
While no nickel alloy is entirely immune to $HCl$, C2000 provides excellent resistance in various concentrations. The synergy between molybdenum and copper allows for stable performance in systems where hydrochloric acid is used as a catalyst or cleaning agent.
Hydrofluoric Acid
C2000 is one of the few Ni-Cr-Mo alloys that offers reliable resistance to hydrofluoric acid. Its ability to maintain structural integrity in $HF$ environments makes it a critical material for the production of refrigerants and high-octane fuels.
Oxidizing Media
Due to its high chromium content, C2000 is highly compatible with oxidizing media, including: Nitric acid Mixed acid systems containing oxidizing salts.Process streams contaminated with ferric or cupric chlorides.
Resistance to Localized Attack
In industrial piping, the most common failures are not uniform thinning but localized attacks. Forged C2000 fittings are highly resistant to:
Pitting: The high molybdenum content prevents the initiation of small holes in the metal surface.
Crevice Corrosion: It maintains a protective oxide film even in tight spaces where stagnant fluids might collect.
Stress Corrosion Cracking (SCC): As a nickel-base alloy, C2000 is virtually immune to chloride-induced SCC, a common failure mode for 300-series stainless steels.
Performance in Oxidizing and Reducing Environments
The high chromium content bolsters resistance to oxidizing agents, including ferric ions and dissolved oxygen in process streams. In reducing environments, it withstands chloride-bearing solutions without stress corrosion cracking, enduring 1,008 hours in boiling 45% magnesium chloride-far exceeding 316L stainless steel. It also performs well in mixed acid media, such as those encountered in pollution control.
Pitting and Crevice Corrosion Resistance
Hastelloy C2000 demonstrates outstanding resistance to localized corrosion. Its critical pitting temperature exceeds 145°C, and critical crevice temperature reaches 80°C in acidified ferric chloride tests, higher than C-276 alloy. In seawater tests, it shows no crevice attack after 180 days, unlike 316L or 625 alloys.
Comparative Analysis
Compared to other materials, Hastelloy C2000 provides broader versatility. It excels over C-276 in sulfuric acid resistance and matches or exceeds it in hydrochloric acid and crevice corrosion metrics. Against stainless steels like 316L and 254SMO, it offers superior durability in chloride environments and acids.
Hastelloy C2000 is the "all-around" solution for aggressive chemical environments. By combining high chromium, molybdenum, and copper, it eliminates the need for engineers to choose between oxidizing or reducing resistance-it delivers both.
