Corrosion Behavior of Steels and Nickel Alloys in Superheated Steam

Abstract

Small amounts of a number of alloying materials were added to Type 304 stainless steel in an effort to improve its corrosion resistance to superheated steam at 650 C (1202 F), 42 kg/cm2. Aluminum and siliconwere valuable additions, but the amount of aluminum required to reduce the corrosion rate significantly embrittled the alloy. Type 304 containing about 3w/oSi appeared to be a practical alloy. In a similar fashion, the addition of about 3w/oAl to Incoloy 800 greatly improved its resistance to static superheated steam. Films stripped from samples corroded in steam with various prior surface preparations were examined by electron microscopy and chemical analysis in an attempt to clarify the reasons for differing corrosion behavior. It was concluded that the rapid diffusion of chromium into the corrosion films formed on mechanically worked surfaces is the key factor in the improved corrosion resistance of these surfaces.

Thermal Convection Loop Study of the Corrosion of Incoloy 800 in Molten NaNO3-KNO3

“…As noted in Table 1, the chemical compositions of both types of material are similar except for carbon content. 19,2° The cold-worked surface layer produced by grinding the coupons would be expected to increase the local diffusivity of Cr, thereby increasing the Cr content of the oxide layers subsequently formed and reducing the corrosion rate relative to annealed material. 12 Similarly, the grain sizes of both types of alloy stock were ASTM 6.…”

Oxidation behavior of Incoloy 800 under simulated supercritical water conditions

“…These alloys show a high tendency to form a protective oxide film in water at high temperatures. Based on its advantages such as high strength and corrosion resistance at high temperatures, Incoloy 800 (a high nickel alloy) is a candidate for Generation IV supercritical watercooled nuclear plant design [4]. The present work aims at evaluating the general corrosion behavior of Incoloy 800 tubes exposed under supercritical water conditions for up to 1440 h. Gravimetry, optical microscopy, scanning electron microscopy/energy dispersion X-ray spectroscopy (SEM/EDS), X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS) were used to analyze oxide growth and stability.…”

Effect of Surface Modification on Candidate Alloys for Canadian SCWR Fuel Cladding

“…Maekawa et al [13] reported a clear difference in corrosion behaviour between electropolished, pickled, or abraded (400 grit abrasive paper) samples. They found the corrosion resistance was different above and below the critical point.…”