Study on initial stage of metal dusting corrosive on Inconel 601 and Incoloy 800

Abstract

Metal dusting is a corrosive phenomenon of metals or alloys into fine, dust-like particles. It can be found in many industrial units or processes, such as petrochemical industry. Metal dusting is initiated by unwanted carbon formation on the inner surface of alloy equipment while the alloy is exposed to gas atmosphere with high carbon activity at high temperature and pressure. Carbon is formed by CO reduction or Boudouard reaction. The main objective of this paper is to investigate how Fe-based (Incoloy 800) and Ni based (Inconel 601) alloy samples perform with different CO exposure time under high pressure metal dusting environment. All samples are polished and pretreated with steam oxidation. Then the samples are exposed to carbonizing atmosphere at 750 °C, at 20 bar in 100Nml/min gas flow with a CO/H2/CO2/H2O/Ar gas mixture of composition 20/25/15/10/30 (vol.%) for 10min to 20 h. Samples after CO exposure are studied by scanning electron microscopy and Raman spectroscopy. And the results show that evident carbon formats on Inconel 601 surface, while no carbon formats on Incoloy 800 surface, however, composition change occurs