HastelloyC-276 Overview

HastelloyC-276 is an improved ultra-low carbon Ni-Mo-Cr series nickel-based corrosion-resistant alloy. It exhibits excellent resistance to various highly corrosive media and chemical substances, as well as strong resistance to stress corrosion cracking. Currently, it is widely used in aviation, chemical engineering, power plant desulfurization, and other fields. Due to its outstanding corrosion resistance, C276 has been selected as one of the candidate materials for cladding in China.

Currently, the recognized representative candidate materials for SCWR cladding include ferritic/martensitic steel, austenitic stainless steel, nickel-based alloys, and ODS. Nickel-based alloy C276 is a nickel-based alloy with high Cr and Mo content. Owing to its excellent corrosion resistance, it is extensively used in the chemical industry and desulfurization equipment of thermal power plants, and thus its corrosion resistance has been widely studied.

HastelloyC-276 Chemical Composition

Physical Properties of Hastelloy C-276:

Mechanical Properties of Hastelloy C-276 at Room Temperature:

C276 Tensile Mechanical Properties

Below 600°C, the yield strength and fracture strength of nickel-based material C276 decrease as temperature increases; above 600°C, both yield strength and fracture strength also decline, but there is a peak strength around 600°C. From the perspective of true stress-strain, the fracture strength of nickel-based material C276 increases with rising temperature below 600°C, but decreases above 600°C, with a peak strength around 600°C. Analysis shows that the fracture strength under true stress and strain is significantly higher than that under nominal stress and strain.

C276 Corrosion Performance

In supercritical water at 550–650°C/25 MPa, C276 alloy primarily undergoes uniform corrosion, and its corrosion weight gain follows a parabolic growth law.

When the temperature increases from 550°C to 600°C, the corrosion weight gain of C276 alloy increases by approximately three times, but when the temperature further rises to 650°C, the corrosion weight gain is only twice that at 550°C.

The solubility of metal oxides in supercritical water is low. The corrosion mechanism of C276 alloy in supercritical water involves solid-state growth, where metal ions from the substrate diffuse outward and external O2? diffuses inward, leading to oxidation reactions that form an oxide film on the material surface.

The oxide film on the surface of C276 alloy shows indistinct layering, with the main component being (Ni, Fe)Cr?O?, while a large number of NiO oxide particles are discretely distributed on the surface layer. The protective performance of the oxide film mainly depends on the Cr content within it; higher Cr content results in a denser structure, which better inhibits the diffusion of metal ions and O2?. The above is an introduction to the material and properties of C276 Hastelloy nickel-based alloy.

Various specifications of plates, bars, strips, wires, discs, ring blanks, and ring forgings are available. Bars are supplied in forged-rolled condition, with surface ground or turned; discs and ring blanks are supplied in forged condition; rings are supplied in solution-treated condition; plates are supplied after solution treatment, alkali pickling, straightening, and edge trimming; strips are delivered after cold rolling, solution treatment, and descaling; wires are supplied in solution-pickled coil or straight form, or in solution-treated straight fine-ground condition.