An Evaluation of Corrosion Resistant Alloys by Field Corrosion Test in Japanese Refuse Incineration Plants

Abstract As the first step for development of the corrosion resistant superheater tube materials of 500°C, 100 ata used in high efficient waste-to-energy plants, field corrosion tests of six conventional alloys were carried out at metal temperatures of 450°C and 550°C for 700 and 3000 hours in four typical Japanese waste incineration plants. The test results indicate that austenitic alloys containing approximately 80 wt% [Cr+Ni] show excellent corrosion resistance. When the corrosive environment is severe, intergranular corrosion of 40~200 μm depth occurs in stainless steel and high alloyed materials. It is confirmed quantitatively that corrosion behavior is influenced by environmental corrosion factors such as Cl concentration and thickness of deposits on tube surface, metal temperature, and flue gas temperature. The excellent corrosion resistance of high [Cr+Ni+Mo] alloys such as Alloy 625 is explained by the stability of its protective oxide, such that the time dependence of corrosion nearly obeys the parabolic rate law. A good correlation was observed between the laboratory corrosion test obtained by means of crucible method and field corrosion tests in comparison with coating method.